Serve a cache hit with no database read or write (closes #309)

A hit opens the variant file and nothing else: its content type comes
from the file's first bytes, and a file in no output format is a miss.
Its access time and hit count, and the access time of a cached source a
miss uses, are handed without waiting to the goroutine that wrote late
counts, which now writes every count and access time once a second;
each kind of access time waits in a channel of 10,000 that drops the
rest. checkNegativeCache leaves expired rows to CleanExpired. The .meta
files, metaCache, Lookup and golang-lru go, with their tests. make bench
runs a parallel cache hit benchmark with Go on the host, outside make
check.

Model: opus-5-5

TODO.md

@@ -30,261 +30,6 @@ P2: security: per-origin rate limiting
 
 # Completed Steps
 
-- 2026-10-27 the reconciliation pass skips a directory it cannot list and a file
-  whose info it cannot read, and goes on (closes #343). It stopped before its
-  later checks at a directory it could not list, or at a source or variant file
-  whose info it could not read.
-    - It logs the warning "skipped unreadable entry in cache directory", with
-      the path and the error.
-    - A file renamed or removed after its directory was listed gets no warning.
-    - `reconcileFiles` reads each file's info once, before the temp-file check,
-      and hands it to `sweepStaleTempFile`, `reconcileVariantFile` or
-      `reconcileSourceFile`.
-    - A cancelled context still stops the walk with its error.
-- 2026-10-26 the reconciliation pass drops a variant's accounting row only when
-  its file is missing (closes #340). Any other error reading the file's size
-  keeps the row. It dropped the row on any error and logged the file as missing.
-    - The kept row gets the warning "kept accounting row for unreadable variant
-      file", with the variant key and the error.
-    - The pass checks for `ErrNotFound`, which `FileStore.Size` returns for a
-      missing file.
-- 2026-10-26 on both image routes, a request is answered 499 and logged at info
-  level when its client goes away before its image is ready, unless it is the
-  request making the image (closes #339). It was answered 500 and logged at
-  error level, as pixa's own failure.
-    - The line is "client went away before the image was ready". It carries the
-      `request_id`, the host and the path.
-    - The 499 has no body, since nobody reads it.
-    - `serveImage` answers it before calling `respondImageError`, which cannot
-      see the request's context.
-    - An error wrapping `context.Canceled` while the request's context is live
-      is still answered 500 and logged at error level.
-- 2026-10-26 `README.md`'s Design section starts with a Concepts list (closes
-  #321). Each concept gets one sentence, under the name the code gives it.
-    - Storage calls the transformed images variants, in shorter sentences.
-    - Storage's paths end in the source key and the variant key.
-    - Storage lists the image cache's tables in the database.
-    - Architecture names `internal/providers`, and lists the packages that work
-      with the concepts.
-- 2026-10-26 one table in `internal/config` lists every setting once (closes
-  #320). `Config.settings` gives each setting's key, its environment variable
-  and the function that loads it.
-    - Most rows load through `field`, whose arguments give the setting's type,
-      its default and its check.
-    - `db_url` and `cache_max_bytes` have their own load functions. The default
-      of `db_url` comes from `state_dir`, and `cache_max_bytes` records whether
-      it is set.
-    - Loading, the unknown-key check, the unknown-variable check and the names
-      in error messages all read the table.
-    - `allowlist_hosts` loads as `referer_blocklist` does, through
-      `parseHostList`.
-    - The metrics username and password are checked together once the table has
-      loaded.
-    - When a config holds more than one invalid value, the error names the one
-      that comes first in the table.
-    - `README.md` lists the settings one item each, where it had a table. A test
-      checks that this list and `configs/config.example.yml` name exactly the
-      keys of the table.
-    - The key constants moved to the tests, their only users.
-    - Removed:
-        - `isKnownConfigKey`, `envVarNames`, `strictLoader` and `validate`
-        - `validateAllowlistHostsValue` and `getStringSlice`, with the three
-          tests of `getStringSlice`
-- 2026-10-26 a fetched image's format is detected from its bytes once, as an
-  `imagerequest.Format` (closes #319). The upstream `Content-Type` check in the
-  fetcher stays as the filter before downloading.
-    - `magic.DetectFormat` returns an `imagerequest.Format`, and
-      `magic.ValidateMagicBytes` returns the format it checked against the
-      `Content-Type`.
-    - `Format.MIMEType` gives each format's MIME type. The fetcher, the mock
-      fetcher, the cache's read of a variant's type and the handler's `Accept`
-      matching use it.
-    - `Cache.Source` returns a source's format, read from its file's first bytes
-      as `Cache.Variant` reads a variant's. A file in no source format is an
-      error, and the proxy fetches the source again.
-    - The proxy hands the format to `ImageProcessor.Process`. The processor
-      refuses input that libvips would load as another format, as before, with
-      `ErrUnsupportedInputFormat`. It refuses a format that is not one of the
-      six source formats the same way.
-    - `internal/magic` no longer detects SVG, which pixa does not read. SVG data
-      is `ErrUnknownFormat`.
-    - Removed:
-        - `magic.MIMEType`, `magic.ImageFormat` and `magic.MIMEToImageFormat`
-        - `detectFormat`, `formatFromString`, `FormatToMIME` and
-          `Result.InputFormat` of the processor
-        - the fetcher's MIME constants of the six formats
-        - `errNotAnOutputFormat` of the cache
-- 2026-10-26 the cache keeps its source images in one `imgcache.FileStore` and
-  its variants in another (closes #318). A `FileStore` is a directory of files,
-  each named by a hex key, at `<ab>/<cd>/<key>`.
-    - `ContentStorage` and `VariantStorage` are gone.
-    - `FileStore` has these methods:
-        - `Write`, which writes a file under a temp name, syncs it and renames
-          it into place
-        - `Open`, which returns the file and its size
-        - `Size`
-        - `Delete`
-    - `FileStore` has no `Exists`. The reconciliation pass checks that a
-      variant's file is there with `Size`. The tests look for the file on disk.
-    - `Cache.Variant` reads the content type from the variant file's first
-      bytes, as `VariantStorage.LoadWithContentType` did. A cache hit still
-      makes no database call.
-    - `storage.go` is now `filestore.go`. `internal/imgcache/testdata/red.avif`,
-      which no test used, is gone.
-- 2026-10-26 `internal/imgcache` holds the cache only (closes #317). The new
-  package `internal/imageproxy` fetches, transforms, caches and serves images.
-  It imports `imgcache`, and `imgcache` does not import it.
-    - `imgcache.Service` is `imageproxy.Proxy`, built by `imageproxy.New` from
-      an `imageproxy.Config`.
-    - `ImageResponse`, `CacheStatus`, `ErrNegativeCached` and
-      `ErrProcessingTimedOut` moved with it, under their names.
-    - `imgcache.CacheConfig` is `imgcache.Config`.
-    - The cache has one read and one write for each kind it keeps. Each takes
-      the place of an earlier method:
-        - `Variant`, of `GetVariant`
-        - `PutVariant`, of `StoreVariant`
-        - `Source`, of `LookupSource` followed by `GetSourceContent`
-        - `PutSource`, of `StoreSource`
-        - `Failure`, of `checkNegativeCache`
-        - `PutFailure`, of `StoreNegative`
-    - `Variant` and `Source` each open the file and hand its access time to the
-      background writer. A cache hit still makes no database call.
-    - `imgcache.go` and `module.go` are gone.
-    - `imageproxy.New` makes the counters of upstream fetches and transforms,
-      and registers them on the registry it is given. The cache keeps only the
-      hit and miss counters.
-    - A cached source whose row cannot be read is logged as "failed to load
-      cached source, fetching". It was logged as "source lookup failed".
-    - The proxy's tests moved to `internal/imageproxy`. They reach the cache
-      through its database, its state directory and its metrics registry.
-    - The tests of an empty or cut cached file are split in two:
-        - `internal/imgcache` checks that the reconciliation pass removes the
-          file and its row, with a warning naming the file.
-        - `internal/imageproxy` removes the file and its row as the pass does,
-          and checks that `Get` fetches or converts again.
-- 2026-10-26 both image routes serve an image with one function, `serveImage`,
-  and answer its errors with one, `respondImageError` (closes #316).
-  `HandleImage` parses the path and verifies the signature, and `HandleImageEnc`
-  decrypts the token. Each then calls `serveImage`.
-    - `handleImageError`, the encrypted route's own mapping, is gone.
-    - `/v1/image/` answers 504 when the upstream has not sent its response
-      headers within `upstream_fetch_timeout`, as `/v1/e/` did. It answered 500.
-    - `respondImageError` logs the image service's errors as "failed to get
-      image". Each answer gets the same level on `/v1/image/` and on `/v1/e/`:
-        - 500: error, as pixa's own failure
-        - 400: warn
-        - 403: warn
-        - 415: warn
-        - 502: warn
-        - 503: warn
-        - 504: warn
-    - Before, `/v1/image/` logged all of these answers at error level. `/v1/e/`
-      logged only its 500, as "image request failed", without the host and the
-      path.
-    - `respondImageError` does not log the 415 for a body refused for its first
-      bytes, on either route. The image service logs it as "source refused", at
-      warn level.
-    - The "image served" line carries the host, the path and `fetched_bytes` on
-      both routes. The debug line "encrypted image request" is gone.
-    - The debug line "failed to decrypt URL" is now "invalid encrypted URL". A
-      token that decrypts to a payload that does not decode also gets it.
-    - A failed write is logged once, as "failed to write response" at warn
-      level, since most often the client has gone away. It carries the
-      `request_id`, the host, the path, `served_bytes` and the error, and is not
-      also logged as "image served".
-- 2026-10-26 every key derived from the signing key is derived in one place
-  (closes #315): `seal.DeriveKeys` returns them as one `seal.Keys`, with their
-  salts declared beside it. `internal/providers` calls it once at startup. Each
-  key is derived as before, with `seal.DeriveKey` and the same salt.
-    - The session manager, the encrypted URL generator and the CSRF protection
-      each take their own key instead of the signing key.
-    - `session.NewManager`, `encurl.NewGenerator`, `newCSRFProtect` and
-      `handlers.New` return no error, as nothing in them can fail now.
-    - The signing key itself stays the HMAC key of signed URLs and the login
-      password.
-    - `README.md` says under `signing_key` what it protects.
-- 2026-10-26 the image request holds only what names the cached object (closes
-  #314): its source and its transform, which the variant key covers. The signed
-  URL format, the signing algorithm and every route's answers are unchanged.
-    - The `/v1/image/` handler checks `allowlist_hosts` and verifies the
-      signature itself, with `Signer.Verify(req, sig, expires)`.
-    - Each image handler keeps its URL's expiry as a value of its own, for
-      `Cache-Control`. `encurl`'s `Generate` takes the expiry and its `Parse`
-      returns it.
-    - The fetcher takes the source and builds its URL with `Source.URL`, over
-      http only when the fetcher's own `AllowHTTP` is set. `validateURL` takes
-      that URL, so no URL string is built and parsed again.
-    - `chooseAutoFormat` returns the format it chooses, and the handler puts it
-      into the request it parsed.
-    - The image service serves images through `Get`, and has `WaitForProcessing`
-      for shutdown.
-    - Removed:
-        - `Signature`, `Expires`, `AllowHTTP` and `SourceURL` of the image
-          request
-        - `Service.ValidateRequest`, and the service's signer, allowlist and
-          `AllowHTTP`
-        - `extractHost` of the fetcher and `urlToFSPath` of the mock fetcher
-- 2026-10-26 pixad's fx graph builds the image pipeline (closes #313).
-  `database.New` now opens the database, so the parts below can read it while
-  they are built; its stop hook still runs after the cache's. The cache's
-  `MaxBytes` is the one value for the disk cache limit, and 0 turns the disk
-  cache off. For an omitted `cache_max_bytes`, `internal/providers` works out
-  `config.DefaultCacheMaxBytes` before it builds the cache. `internal/app` and
-  the server tests build the parts below with `providers.Constructors()`; the
-  image proxy test replaces only the fetcher's dial function.
-    - Built by the providers in `internal/providers`, and given to
-      `handlers.New`:
-        - the cache
-        - the fetcher
-        - the processor
-        - the image service
-        - the session manager
-        - the encrypted URL generator
-    - Removed:
-        - `initImageService` and `handlers.Params.Fetcher`
-        - `CacheConfig.UseDefaultMaxBytes`, `CacheConfig.DisableDiskCache` and
-          `Cache.disabled`
-        - `httpfetcher.DefaultConfig()` and the fetcher's copies of setting
-          defaults
-        - `imageprocessor.DefaultMaxInputBytes`, and the processor's defaults
-          for a zero `MaxInputBytes` or `MaxConcurrentProcessing`
-- 2026-10-26 the code nothing in production called is gone (closes #312). The
-  handlers tests sign their image URLs with `generateSignedURL`, a test helper
-  that writes them as the removed generator did. Removed:
-    - `Service.Warm` and the `ImageCache` interface
-    - `Service.GenerateSignedURL` and `Signer.GenerateSignedURL`
-    - `signature.ParseParams`
-    - `imagerequest.ParseImagePath`
-    - `PeekAndValidate`, `IsSupportedMIMEType`, `ImageFormatToMIME` and
-      `FormatOriginal` of `internal/magic`
-    - `SupportedInputFormats` and `SupportedOutputFormats` of the image
-      processor
-    - `IsEmpty` and `Count` of the allowlist
-    - `ssrfSafeDialer`
-    - `CacheStale`, `ErrCacheMiss`, `ErrNegativeCache` and
-      `ImageResponse.LastModified`
-    - `ContentStorage.Load` and `VariantStorage.Load`
-- 2026-10-26 cache hits, misses, upstream fetches, the bytes those fetches read
-  and transforms are counted as Prometheus counters in memory (closes #311).
-  They are `pixa_cache_hits_total`, `pixa_cache_misses_total`,
-  `pixa_upstream_fetches_total`, `pixa_upstream_fetch_bytes_total` and
-  `pixa_transforms_total`, fields of the cache. `NewCache` makes them and
-  registers them on the registry it is given (`internal/imgcache/counters.go`).
-  pixad gives it Prometheus' default registry, which `/metrics` serves; each
-  test gives it a new one. The `Increment` methods add to their cache's
-  counters. `cache_stats`, `Cache.Stats`, `Service.Stats`, `CacheStats` and the
-  pending counts are gone. The background goroutine writes only access times
-  now: `StartPendingAccessTimeWrites` starts it and
-  `StopPendingAccessTimeWrites` stops it, in `pendingaccesstimes.go`.
-- 2026-10-21 the schema file declares only the tables and columns pixa writes
-  and reads (closes #310): `output_content` and `request_cache` are gone, and so
-  are the columns nothing read: the host, path, query, `content_type` and
-  `fetched_at` of `source_content`, the `content_type` and `created_at` of
-  `variant_content`, and the `status_code`, `error_message` and `fetched_at` of
-  `negative_cache`. `StoreSource` no longer takes the fetch result,
-  `LookupSource` returns only the source key, `StoreVariant` no longer takes a
-  content type, `StoreNegative` no longer takes a status code or message, and
-  reconciliation adopts a variant file without reading its first bytes.
 - 2026-10-21 a cache hit makes no database call (closes #309): `Service.Get`
   opens the variant file with `Cache.GetVariant` and nothing else, with no
   existence check first. The content type comes from the file's first bytes; a

internal/allowlist/allowlist.go

@@ -72,3 +72,13 @@ func (w *HostAllowList) IsAllowed(u *url.URL) bool {
 
 	return false
 }
+
+// IsEmpty returns true if the allow list has no entries.
+func (w *HostAllowList) IsEmpty() bool {
+	return len(w.exactHosts) == 0 && len(w.suffixHosts) == 0
+}
+
+// Count returns the total number of allow list entries.
+func (w *HostAllowList) Count() int {
+	return len(w.exactHosts) + len(w.suffixHosts)
+}

internal/allowlist/allowlist_test.go

@@ -139,3 +139,87 @@ func TestHostAllowList_IsAllowed_SuffixMatch(t *testing.T) {
 		},
 	})
 }
+
+func TestHostAllowList_IsEmpty(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		patterns []string
+		want     bool
+	}{
+		{
+			name:     "empty",
+			patterns: []string{},
+			want:     true,
+		},
+		{
+			name:     "nil",
+			patterns: nil,
+			want:     true,
+		},
+		{
+			name:     "whitespace only",
+			patterns: []string{"  ", ""},
+			want:     true,
+		},
+		{
+			name:     "has entries",
+			patterns: []string{"example.com"},
+			want:     false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			w := allowlist.New(tt.patterns)
+			if got := w.IsEmpty(); got != tt.want {
+				t.Errorf("IsEmpty() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestHostAllowList_Count(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		patterns []string
+		want     int
+	}{
+		{
+			name:     "empty",
+			patterns: []string{},
+			want:     0,
+		},
+		{
+			name:     "exact hosts only",
+			patterns: []string{"a.com", "b.com", "c.com"},
+			want:     3,
+		},
+		{
+			name:     "suffix hosts only",
+			patterns: []string{".a.com", ".b.com"},
+			want:     2,
+		},
+		{
+			name:     "mixed",
+			patterns: []string{"exact.com", ".suffix.com"},
+			want:     2,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			w := allowlist.New(tt.patterns)
+			if got := w.Count(); got != tt.want {
+				t.Errorf("Count() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

internal/app/app.go

@@ -7,7 +7,6 @@ import (
 	"os/signal"
 	"syscall"
 
-	"github.com/prometheus/client_golang/prometheus"
 	"github.com/spf13/cobra"
 	"go.uber.org/fx"
 	"sneak.berlin/go/pixa/internal/config"
@@ -17,7 +16,6 @@ import (
 	"sneak.berlin/go/pixa/internal/healthcheck"
 	"sneak.berlin/go/pixa/internal/logger"
 	"sneak.berlin/go/pixa/internal/middleware"
-	"sneak.berlin/go/pixa/internal/providers"
 	"sneak.berlin/go/pixa/internal/server"
 )
 
@@ -63,10 +61,7 @@ func run(_ *cobra.Command, _ []string) {
 			server.New,
 			middleware.New,
 			healthcheck.New,
-			// The registry /metrics serves
-			func() prometheus.Registerer { return prometheus.DefaultRegisterer },
 		),
-		fx.Provide(providers.Constructors()...),
 		fx.Invoke(
 			func(log *logger.Logger) { log.Identify() },
 			func(*server.Server) {},

internal/config/cache_max_bytes_internal_test.go

@@ -135,38 +135,10 @@ func TestCacheMaxBytesInvalidValuesAbortStartup(t *testing.T) {
 	}
 }
 
-// TestDefaultCacheMaxBytesAppliesFloor verifies that when 75% of the
-// free space plus what the cache holds is below 500 MiB, the default is
-// floored at DefaultCacheMaxBytesFloor.
-func TestDefaultCacheMaxBytesAppliesFloor(t *testing.T) {
-	t.Parallel()
-
-	cases := []struct {
-		name      string
-		freeBytes uint64
-	}{
-		{name: "100 MiB free", freeBytes: 104857600},
-		{name: "zero free", freeBytes: 0},
-		{name: "just below floor threshold", freeBytes: 699050665},
-	}
-
-	for _, tc := range cases {
-		t.Run(tc.name, func(t *testing.T) {
-			t.Parallel()
-
-			got := DefaultCacheMaxBytes(tc.freeBytes, 0)
-			if got != DefaultCacheMaxBytesFloor {
-				t.Errorf("DefaultCacheMaxBytes = %d, want floor %d",
-					got, DefaultCacheMaxBytesFloor)
-			}
-		})
-	}
-}
-
 // TestCacheMaxBytesExplicitIsRecorded verifies that an omitted
-// cache_max_bytes is recorded as not explicit, so pixad works out the
-// default when it builds the cache, and that an explicit zero is recorded
-// as explicit, so it disables the disk cache instead.
+// cache_max_bytes is recorded as not explicit, so the cache works out
+// the default when it opens, and that an explicit zero is recorded as
+// explicit, so it disables the disk cache instead.
 func TestCacheMaxBytesExplicitIsRecorded(t *testing.T) {
 	t.Parallel()
 

internal/config/config_internal_test.go

@@ -1,12 +1,97 @@
 package config
 
 import (
+	"os"
 	"path/filepath"
 	"testing"
 
 	"git.eeqj.de/sneak/smartconfig"
 )
 
+// writeTestConfig writes yamlContent to a temp config file and returns
+// the file path.
+func writeTestConfig(t *testing.T, yamlContent string) string {
+	t.Helper()
+
+	tmpDir := t.TempDir()
+	configPath := filepath.Join(tmpDir, "config.yml")
+
+	err := os.WriteFile(configPath, []byte(yamlContent), 0o600)
+	if err != nil {
+		t.Fatalf("failed to write test config: %v", err)
+	}
+
+	return configPath
+}
+
+// checkAllowlistHosts loads the config at configPath and asserts that
+// getStringSlice returns the three expected hosts.
+func checkAllowlistHosts(t *testing.T, configPath string) {
+	t.Helper()
+
+	sc, err := loadTestConfig(configPath)
+	if err != nil {
+		t.Fatalf("failed to load config: %v", err)
+	}
+
+	hosts := getStringSlice(sc)
+
+	if len(hosts) != 3 {
+		t.Errorf("expected 3 hosts, got %d: %v", len(hosts), hosts)
+	}
+
+	expected := []string{"static.sneak.cloud", "sneak.berlin", testHostS3}
+	for i, want := range expected {
+		if i >= len(hosts) {
+			t.Errorf("missing host at index %d: want %q", i, want)
+
+			continue
+		}
+
+		if hosts[i] != want {
+			t.Errorf("host[%d] = %q, want %q", i, hosts[i], want)
+		}
+	}
+}
+
+func TestGetStringSlice_YAMLList(t *testing.T) {
+	t.Parallel()
+
+	yamlContent := `
+allowlist_hosts:
+  - static.sneak.cloud
+  - sneak.berlin
+  - s3.sneak.cloud
+`
+
+	checkAllowlistHosts(t, writeTestConfig(t, yamlContent))
+}
+
+func TestGetStringSlice_CommaSeparated(t *testing.T) {
+	t.Parallel()
+
+	// Backwards compatibility with comma-separated string values.
+	yamlContent := `allowlist_hosts: "static.sneak.cloud, sneak.berlin, s3.sneak.cloud"`
+
+	checkAllowlistHosts(t, writeTestConfig(t, yamlContent))
+}
+
+func TestGetStringSlice_Empty(t *testing.T) {
+	t.Parallel()
+
+	configPath := writeTestConfig(t, `port: 8080`)
+
+	sc, err := loadTestConfig(configPath)
+	if err != nil {
+		t.Fatalf("failed to load config: %v", err)
+	}
+
+	hosts := getStringSlice(sc)
+	if len(hosts) != 0 {
+		t.Errorf("expected nil or empty slice, got %v", hosts)
+	}
+}
+
 // TestExampleConfigAllowlistsNoHost loads configs/config.example.yml
 // with a real signing key, as Getting Started in README.md has it copied
 // and edited, and checks that it allowlists no host: every image on an

internal/config/config_validation_internal_test.go

@@ -15,36 +15,8 @@ import (
 	_ "modernc.org/sqlite" // SQLite driver registration
 )
 
-// The config keys the tests name in the errors they expect.
-const (
-	keyDebug                      = "debug"
-	keyMaintenanceMode            = "maintenance_mode"
-	keyPort                       = "port"
-	keyStateDir                   = "state_dir"
-	keySentryDSN                  = "sentry_dsn"
-	keyDBURL                      = "db_url"
-	keyMetrics                    = "metrics"
-	keyMetricsUsername            = "metrics.username"
-	keyMetricsPassword            = "metrics.password"
-	keySigningKey                 = "signing_key"
-	keyAllowlistHosts             = "allowlist_hosts"
-	keyRefererBlocklist           = "referer_blocklist"
-	keyAllowHTTP                  = "allow_http"
-	keyUpstreamConnectionsPerHost = "upstream_connections_per_host"
-	keyUpstreamConnections        = "upstream_connections"
-	keyMaxConcurrentProcessing    = "max_concurrent_processing"
-	keyCacheMaxBytes              = "cache_max_bytes"
-	keyBlockedNetworks            = "blocked_networks"
-	keyTrustedProxies             = "trusted_proxies"
-	keyAccessControlAllowOrigin   = "access_control_allow_origin"
-	keyUpstreamFetchTimeout       = "upstream_fetch_timeout"
-	keyUpstreamMaxResponseSize    = "upstream_max_response_size"
-	keyDownstreamTimeout          = "downstream_timeout"
-	keyImageRequestsPerMinute     = "image_requests_per_minute"
-)
-
 // validTestSigningKey is a 32-character signing key that satisfies the
-// minimum length requirement in validateSigningKey.
+// minimum length requirement in validate().
 const validTestSigningKey = "0123456789abcdef0123456789abcdef"
 
 // signingKeyLine is a valid signing_key config line used as the base of

internal/config/documented_settings_internal_test.go

@@ -1,127 +0,0 @@
-package config
-
-import (
-	"os"
-	"path/filepath"
-	"regexp"
-	"strings"
-	"testing"
-)
-
-// TestReadmeNamesEverySetting checks that the list of settings in
-// README.md names exactly the keys of the settings table, one item each.
-// The list is the first one in the Configuration section, and it ends at
-// the first blank line. Each item starts with its key in backticks.
-func TestReadmeNamesEverySetting(t *testing.T) {
-	t.Parallel()
-
-	readme, err := os.ReadFile(filepath.Join("..", "..", "README.md"))
-	if err != nil {
-		t.Fatalf("failed to read README.md: %v", err)
-	}
-
-	_, section, found := strings.Cut(string(readme), "\n### Configuration\n")
-	if !found {
-		t.Fatal("README.md has no Configuration section")
-	}
-
-	// The section ends at the next heading of its level or above.
-	section, _, _ = strings.Cut(section, "\n## ")
-	section, _, _ = strings.Cut(section, "\n### ")
-
-	_, list, found := strings.Cut(section, "\n- ")
-	if !found {
-		t.Fatal("README.md's Configuration section has no list")
-	}
-
-	list, _, _ = strings.Cut("- "+list, "\n\n")
-
-	itemKey := regexp.MustCompile("^- `([^`]+)`")
-	named := map[string]bool{}
-
-	for line := range strings.SplitSeq(list, "\n") {
-		// A line that does not start with "- " goes on with the item above.
-		if !strings.HasPrefix(line, "- ") {
-			continue
-		}
-
-		match := itemKey.FindStringSubmatch(line)
-		if match == nil {
-			t.Errorf("README.md's list of settings has an item "+
-				"that does not start with a key in backticks: %s", line)
-
-			continue
-		}
-
-		if named[match[1]] {
-			t.Errorf("README.md's list of settings names %s twice", match[1])
-		}
-
-		named[match[1]] = true
-	}
-
-	for _, s := range new(Config).settings() {
-		if !named[s.key] {
-			t.Errorf("README.md's list of settings does not name %s", s.key)
-		}
-
-		delete(named, s.key)
-	}
-
-	for key := range named {
-		t.Errorf("README.md's list of settings names %s, "+
-			"which is not a setting", key)
-	}
-}
-
-// TestExampleConfigNamesEverySetting checks that
-// configs/config.example.yml names exactly the keys of the settings
-// table, each one set or commented out with "# ". A key line holds the
-// key, a colon and at most a one-word value, which tells it from a
-// comment line that starts with a word and a colon. An indented key is
-// inside the map of the key above it, as username is inside metrics.
-func TestExampleConfigNamesEverySetting(t *testing.T) {
-	t.Parallel()
-
-	const examplePath = "configs/config.example.yml"
-
-	example, err := os.ReadFile(filepath.Join("..", "..", examplePath))
-	if err != nil {
-		t.Fatalf("failed to read %s: %v", examplePath, err)
-	}
-
-	keyLine := regexp.MustCompile(`(?m)^(?:# )?( *)([a-z_]+):(?: \S+)?$`)
-	named := map[string]bool{}
-
-	var mapKey string
-
-	for _, match := range keyLine.FindAllStringSubmatch(string(example), -1) {
-		indent, key := match[1], match[2]
-		if indent == "" {
-			mapKey = key
-			named[key] = true
-
-			continue
-		}
-
-		// The key holding the map is not itself a setting.
-		delete(named, mapKey)
-
-		named[mapKey+"."+key] = true
-	}
-
-	// The env section sets environment variables; it is not a setting.
-	delete(named, "env")
-
-	for _, s := range new(Config).settings() {
-		if !named[s.key] {
-			t.Errorf("%s does not name %s", examplePath, s.key)
-		}
-
-		delete(named, s.key)
-	}
-
-	for key := range named {
-		t.Errorf("%s names %s, which is not a setting", examplePath, key)
-	}
-}

internal/config/env_internal_test.go

@@ -138,8 +138,7 @@ func TestPixaPortAbortsStartupPointingToPort(t *testing.T) {
 
 // TestSettingVariablesAndConfigPathAreAccepted checks that every
 // setting's variable and PIXA_CONFIG_PATH pass the check for unknown
-// PIXA_ variables. TestEnvironmentSetsEveryKey pins the names in the
-// settings table.
+// PIXA_ variables. TestEnvironmentSetsEveryKey pins the names in the list.
 func TestSettingVariablesAndConfigPathAreAccepted(t *testing.T) {
 	// A config file's env section loaded by another test can leave a
 	// PIXA_ variable set for the whole process, so every one is unset
@@ -160,8 +159,8 @@ func TestSettingVariablesAndConfigPathAreAccepted(t *testing.T) {
 
 	t.Setenv("PIXA_CONFIG_PATH", "/etc/pixa/config.yml")
 
-	for _, s := range new(Config).settings() {
-		t.Setenv(s.envVar, "")
+	for _, name := range envVarNames() {
+		t.Setenv(name, "")
 	}
 
 	err := validateKnownEnvVars()

internal/database/concurrent_writes_internal_test.go

@@ -104,31 +104,41 @@ func writeConcurrently(t *testing.T, db *sql.DB) {
 
 	wg.Wait()
 
-	var sources int
+	var hits, sources int
 
-	err := db.QueryRowContext(ctx, `SELECT COUNT(*) FROM source_content`).
-		Scan(&sources)
+	err := db.QueryRowContext(ctx, `
+		SELECT hit_count, (SELECT COUNT(*) FROM source_content)
+		FROM cache_stats WHERE id = 1
+	`).Scan(&hits, &sources)
 	if err != nil {
 		t.Fatalf("failed to count the writes: %v", err)
 	}
 
-	if sources != totalRequests {
-		t.Errorf("%d source_content rows, want %d", sources, totalRequests)
+	if hits != totalRequests || sources != totalRequests {
+		t.Errorf("hit_count = %d and %d source_content rows, want %d of each",
+			hits, sources, totalRequests)
 	}
 }
 
 // writeLikeOneRequest makes the writes one request and the eviction pass
-// make: it stores a source, records a transformed image and deletes that
-// record again.
+// make: it counts a cache hit, stores a source, records a transformed image
+// and deletes that record again.
 func writeLikeOneRequest(ctx context.Context, db *sql.DB, key string) error {
-	_, err := db.ExecContext(ctx, `INSERT INTO source_content
-		(source_key, size_bytes) VALUES (?, 1)`, key)
+	_, err := db.ExecContext(ctx,
+		`UPDATE cache_stats SET hit_count = hit_count + 1 WHERE id = 1`)
+	if err != nil {
+		return fmt.Errorf("counting a cache hit: %w", err)
+	}
+
+	_, err = db.ExecContext(ctx, `INSERT INTO source_content
+		(source_key, source_host, source_path, content_type, size_bytes)
+		VALUES (?, 'example.com', '/image.png', 'image/png', 1)`, key)
 	if err != nil {
 		return fmt.Errorf("storing a source: %w", err)
 	}
 
 	_, err = db.ExecContext(ctx, `INSERT INTO variant_content
-		(cache_key, size_bytes) VALUES (?, 1)`, key)
+		(cache_key, size_bytes, content_type) VALUES (?, 1, 'image/png')`, key)
 	if err != nil {
 		return fmt.Errorf("recording a transformed image: %w", err)
 	}

internal/database/database.go

@@ -82,11 +82,7 @@ func ParseMigrationVersion(filename string) (int, error) {
 	return version, nil
 }
 
-// New opens the database and applies the migrations, so that the parts
-// fx builds after it can read the database while they are built. Its
-// stop hook closes the database. fx runs stop hooks in the reverse of the
-// order it built their parts in, so the stop hooks of those parts run
-// before this one.
+// New creates a new Database instance.
 func New(lc fx.Lifecycle, params Params) (*Database, error) {
 	s := &Database{
 		log:    params.Logger.Get(),
@@ -95,16 +91,20 @@ func New(lc fx.Lifecycle, params Params) (*Database, error) {
 
 	s.log.Info("Database instantiated")
 
-	err := s.connect(context.Background())
-	if err != nil {
-		return nil, err
-	}
-
 	lc.Append(fx.Hook{
+		OnStart: func(ctx context.Context) error {
+			s.log.Info("Database OnStart Hook")
+
+			return s.connect(ctx)
+		},
 		OnStop: func(_ context.Context) error {
 			s.log.Info("Database OnStop Hook")
 
-			return s.db.Close()
+			if s.db != nil {
+				return s.db.Close()
+			}
+
+			return nil
 		},
 	})
 

internal/database/database_internal_test.go

@@ -159,7 +159,10 @@ func TestApplyMigrations_CreatesSchemaAndTables(t *testing.T) {
 	}
 
 	// Verify that the application tables created by 001.sql exist.
-	tables := []string{"source_content", "negative_cache"}
+	tables := []string{
+		"source_content", "output_content",
+		"request_cache", "negative_cache", "cache_stats",
+	}
 	for _, table := range tables {
 		var count int
 

internal/db/migrations/001_schema.sql

@@ -6,7 +6,12 @@
 -- is the SHA-256 of the source's host, path and query
 CREATE TABLE IF NOT EXISTS source_content (
     source_key TEXT PRIMARY KEY,
+    source_host TEXT NOT NULL,
+    source_path TEXT NOT NULL,
+    source_query TEXT NOT NULL DEFAULT '',
+    content_type TEXT NOT NULL,
     size_bytes INTEGER NOT NULL,
+    fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP,
     last_accessed_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
 );
 CREATE INDEX IF NOT EXISTS idx_source_content_last_accessed
@@ -22,6 +27,8 @@ CREATE INDEX IF NOT EXISTS idx_source_content_last_accessed
 CREATE TABLE IF NOT EXISTS variant_content (
     cache_key TEXT PRIMARY KEY,
     size_bytes INTEGER NOT NULL,
+    content_type TEXT NOT NULL,
+    created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
     last_accessed_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
 );
 CREATE INDEX IF NOT EXISTS idx_variant_content_last_accessed
@@ -95,19 +102,63 @@ BEGIN
     WHERE id = 1;
 END;
 
--- Negative cache: source URLs whose fetch failed with an upstream error
--- status, or whose first bytes did not match their Content-Type. pixa does
--- not fetch such a URL again until its row expires.
+-- Output/transformed content blobs
+-- Not written: transformed images are stored in cache/variants and
+-- tracked in variant_content above.
+CREATE TABLE IF NOT EXISTS output_content (
+    content_hash TEXT PRIMARY KEY,
+    content_type TEXT NOT NULL,
+    size_bytes INTEGER NOT NULL,
+    fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP
+);
+
+-- Request cache - maps full request params to output content
+CREATE TABLE IF NOT EXISTS request_cache (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    cache_key TEXT NOT NULL UNIQUE,
+    source_metadata_id INTEGER NOT NULL,
+    output_hash TEXT NOT NULL,
+    width INTEGER NOT NULL,
+    height INTEGER NOT NULL,
+    format TEXT NOT NULL,
+    quality INTEGER NOT NULL DEFAULT 85,
+    fit_mode TEXT NOT NULL DEFAULT 'cover',
+    fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+    access_count INTEGER NOT NULL DEFAULT 1,
+    FOREIGN KEY (source_metadata_id) REFERENCES source_metadata(id),
+    FOREIGN KEY (output_hash) REFERENCES output_content(content_hash)
+);
+CREATE INDEX IF NOT EXISTS idx_request_cache_key ON request_cache(cache_key);
+CREATE INDEX IF NOT EXISTS idx_request_cache_source ON request_cache(source_metadata_id);
+CREATE INDEX IF NOT EXISTS idx_request_cache_output ON request_cache(output_hash);
+CREATE INDEX IF NOT EXISTS idx_request_cache_fetched ON request_cache(fetched_at);
+
+-- Negative cache for failed fetches (404s, timeouts, etc.)
 CREATE TABLE IF NOT EXISTS negative_cache (
     id INTEGER PRIMARY KEY AUTOINCREMENT,
     source_host TEXT NOT NULL,
     source_path TEXT NOT NULL,
     source_query TEXT NOT NULL DEFAULT '',
+    status_code INTEGER NOT NULL,
+    error_message TEXT,
+    fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP,
     expires_at DATETIME NOT NULL,
     UNIQUE(source_host, source_path, source_query)
 );
 CREATE INDEX IF NOT EXISTS idx_negative_cache_expires ON negative_cache(expires_at);
 
+-- Cache statistics for monitoring
+CREATE TABLE IF NOT EXISTS cache_stats (
+    id INTEGER PRIMARY KEY CHECK (id = 1),
+    hit_count INTEGER NOT NULL DEFAULT 0,
+    miss_count INTEGER NOT NULL DEFAULT 0,
+    upstream_fetch_count INTEGER NOT NULL DEFAULT 0,
+    upstream_fetch_bytes INTEGER NOT NULL DEFAULT 0,
+    transform_count INTEGER NOT NULL DEFAULT 0,
+    last_updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
+);
+INSERT OR IGNORE INTO cache_stats (id) VALUES (1);
+
 -- A random value that a login session carries from its login. pixa makes it
 -- when the table has no row, and each logout replaces it; a login session
 -- carrying another value is refused, so logging out ends every login session.

internal/encurl/encurl.go

@@ -16,6 +16,9 @@ const (
 	DefaultQuality = 85
 	DefaultFormat  = imagerequest.FormatJXL
 	DefaultFitMode = imagerequest.FitCover
+
+	// HKDF salt for URL encryption key derivation
+	urlKeySalt = "pixa-urlenc-v1"
 )
 
 // Errors returned by encurl operations.
@@ -45,20 +48,23 @@ type Generator struct {
 	key [seal.KeySize]byte
 }
 
-// NewGenerator creates an encrypted URL generator that encrypts its tokens
-// with key.
-func NewGenerator(key [seal.KeySize]byte) *Generator {
-	return &Generator{key: key}
+// NewGenerator creates an encrypted URL generator with a key derived
+// from the signing key.
+func NewGenerator(signingKey string) (*Generator, error) {
+	key, err := seal.DeriveKey([]byte(signingKey), urlKeySalt)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Generator{key: key}, nil
 }
 
-// Generate creates an encrypted URL token from the request's source and
-// transform, each as the request holds it, and from expires; an empty format,
-// a quality of 0 or an empty fit mode is left out of the token, and a zero
-// expires makes a token that never expires. The token is CBOR-encoded,
+// Generate creates an encrypted URL token from the request's source,
+// transform and expiry, each as the request holds it; an empty format, a
+// quality of 0 or an empty fit mode is left out of the token, and a zero
+// Expires makes a token that never expires. The token is CBOR-encoded,
 // encrypted with NaCl secretbox, and base64url-encoded.
-func (g *Generator) Generate(
-	req *imagerequest.Request, expires time.Time,
-) (string, error) {
+func (g *Generator) Generate(req *imagerequest.Request) (string, error) {
 	p := &payload{
 		SourceHost:  req.Source.Host,
 		SourcePath:  req.Source.Path,
@@ -70,8 +76,8 @@ func (g *Generator) Generate(
 		FitMode:     req.Transform.FitMode,
 	}
 
-	if !expires.IsZero() {
-		p.ExpiresAt = expires.Unix()
+	if !req.Expires.IsZero() {
+		p.ExpiresAt = req.Expires.Unix()
 	}
 
 	// CBOR encode the payload
@@ -85,19 +91,19 @@ func (g *Generator) Generate(
 }
 
 // Parse decrypts and validates an encrypted URL token and returns the
-// request it holds, with default values for omitted optional fields, and its
-// expiry. A token that never expires gives the zero time.
+// request it holds, with default values for omitted optional fields. A token
+// that never expires gives the zero Expires.
 // Returns ErrExpired if the token has expired, or other errors for invalid tokens.
-func (g *Generator) Parse(token string) (*imagerequest.Request, time.Time, error) {
+func (g *Generator) Parse(token string) (*imagerequest.Request, error) {
 	// Decrypt
 	data, err := seal.Decrypt(g.key, token)
 	if err != nil {
 		if errors.Is(err, seal.ErrDecryptionFailed) ||
 			errors.Is(err, seal.ErrInvalidPayload) {
-			return nil, time.Time{}, ErrDecryptFailed
+			return nil, ErrDecryptFailed
 		}
 
-		return nil, time.Time{}, err
+		return nil, err
 	}
 
 	// CBOR decode
@@ -105,12 +111,12 @@ func (g *Generator) Parse(token string) (*imagerequest.Request, time.Time, error
 
 	err = cbor.Unmarshal(data, &p)
 	if err != nil {
-		return nil, time.Time{}, ErrInvalidFormat
+		return nil, ErrInvalidFormat
 	}
 
 	// Check expiration (0 = never expires)
 	if p.ExpiresAt != 0 && time.Now().Unix() > p.ExpiresAt {
-		return nil, time.Time{}, ErrExpired
+		return nil, ErrExpired
 	}
 
 	format := p.Format
@@ -145,5 +151,6 @@ func (g *Generator) Parse(token string) (*imagerequest.Request, time.Time, error
 			Quality: quality,
 			FitMode: fitMode,
 		},
-	}, expires, nil
+		Expires: expires,
+	}, nil
 }

internal/encurl/encurl_test.go

@@ -7,7 +7,6 @@ import (
 
 	"sneak.berlin/go/pixa/internal/encurl"
 	"sneak.berlin/go/pixa/internal/imagerequest"
-	"sneak.berlin/go/pixa/internal/seal"
 )
 
 // Shared test fixture strings.
@@ -20,13 +19,11 @@ const (
 func TestGenerator_GenerateAndParse(t *testing.T) {
 	t.Parallel()
 
-	keys, err := seal.DeriveKeys("test-signing-key-12345")
+	gen, err := encurl.NewGenerator("test-signing-key-12345")
 	if err != nil {
-		t.Fatalf("seal.DeriveKeys() error = %v", err)
+		t.Fatalf("NewGenerator() error = %v", err)
 	}
 
-	gen := encurl.NewGenerator(keys.EncryptedURLKey)
-
 	req := &imagerequest.Request{
 		Source: imagerequest.Source{
 			Host:  testSourceHost,
@@ -39,10 +36,10 @@ func TestGenerator_GenerateAndParse(t *testing.T) {
 			Quality: 90,
 			FitMode: imagerequest.FitContain,
 		},
+		Expires: time.Now().Add(time.Hour),
 	}
-	expires := time.Now().Add(time.Hour)
 
-	token, err := gen.Generate(req, expires)
+	token, err := gen.Generate(req)
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}
@@ -51,7 +48,7 @@ func TestGenerator_GenerateAndParse(t *testing.T) {
 		t.Fatal("Generate() returned empty token")
 	}
 
-	parsed, parsedExpires, err := gen.Parse(token)
+	parsed, err := gen.Parse(token)
 	if err != nil {
 		t.Fatalf("Parse() error = %v", err)
 	}
@@ -94,30 +91,30 @@ func TestGenerator_GenerateAndParse(t *testing.T) {
 			parsed.Transform.FitMode, req.Transform.FitMode)
 	}
 
-	if parsedExpires.Unix() != expires.Unix() {
-		t.Errorf("ExpiresAt = %d, want %d", parsedExpires.Unix(), expires.Unix())
+	if parsed.Expires.Unix() != req.Expires.Unix() {
+		t.Errorf("ExpiresAt = %d, want %d", parsed.Expires.Unix(), req.Expires.Unix())
 	}
 }
 
 func TestGenerator_Parse_Expired(t *testing.T) {
 	t.Parallel()
 
-	keys, _ := seal.DeriveKeys("test-signing-key-12345")
-	gen := encurl.NewGenerator(keys.EncryptedURLKey)
+	gen, _ := encurl.NewGenerator("test-signing-key-12345")
 
 	req := &imagerequest.Request{
 		Source: imagerequest.Source{
 			Host: testSourceHost,
 			Path: testSourcePath,
 		},
+		Expires: time.Now().Add(-time.Hour), // Already expired
 	}
 
-	token, err := gen.Generate(req, time.Now().Add(-time.Hour)) // Already expired
+	token, err := gen.Generate(req)
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}
 
-	_, _, err = gen.Parse(token)
+	_, err = gen.Parse(token)
 	if err == nil {
 		t.Error("Parse() should fail for expired token")
 	}
@@ -130,10 +127,9 @@ func TestGenerator_Parse_Expired(t *testing.T) {
 func TestGenerator_Parse_InvalidToken(t *testing.T) {
 	t.Parallel()
 
-	keys, _ := seal.DeriveKeys("test-signing-key-12345")
-	gen := encurl.NewGenerator(keys.EncryptedURLKey)
+	gen, _ := encurl.NewGenerator("test-signing-key-12345")
 
-	_, _, err := gen.Parse("not-a-valid-token")
+	_, err := gen.Parse("not-a-valid-token")
 	if err == nil {
 		t.Error("Parse() should fail for invalid token")
 	}
@@ -142,17 +138,17 @@ func TestGenerator_Parse_InvalidToken(t *testing.T) {
 func TestGenerator_Parse_TamperedToken(t *testing.T) {
 	t.Parallel()
 
-	keys, _ := seal.DeriveKeys("test-signing-key-12345")
-	gen := encurl.NewGenerator(keys.EncryptedURLKey)
+	gen, _ := encurl.NewGenerator("test-signing-key-12345")
 
 	req := &imagerequest.Request{
 		Source: imagerequest.Source{
 			Host: testSourceHost,
 			Path: testSourcePath,
 		},
+		Expires: time.Now().Add(time.Hour),
 	}
 
-	token, _ := gen.Generate(req, time.Now().Add(time.Hour))
+	token, _ := gen.Generate(req)
 
 	// Tamper with the token
 	tampered := []byte(token)
@@ -160,7 +156,7 @@ func TestGenerator_Parse_TamperedToken(t *testing.T) {
 		tampered[10] ^= 0x01
 	}
 
-	_, _, err := gen.Parse(string(tampered))
+	_, err := gen.Parse(string(tampered))
 	if err == nil {
 		t.Error("Parse() should fail for tampered token")
 	}
@@ -169,21 +165,20 @@ func TestGenerator_Parse_TamperedToken(t *testing.T) {
 func TestGenerator_Parse_WrongKey(t *testing.T) {
 	t.Parallel()
 
-	keys1, _ := seal.DeriveKeys("signing-key-1")
-	keys2, _ := seal.DeriveKeys("signing-key-2")
-	gen1 := encurl.NewGenerator(keys1.EncryptedURLKey)
-	gen2 := encurl.NewGenerator(keys2.EncryptedURLKey)
+	gen1, _ := encurl.NewGenerator("signing-key-1")
+	gen2, _ := encurl.NewGenerator("signing-key-2")
 
 	req := &imagerequest.Request{
 		Source: imagerequest.Source{
 			Host: testSourceHost,
 			Path: testSourcePath,
 		},
+		Expires: time.Now().Add(time.Hour),
 	}
 
-	token, _ := gen1.Generate(req, time.Now().Add(time.Hour))
+	token, _ := gen1.Generate(req)
 
-	_, _, err := gen2.Parse(token)
+	_, err := gen2.Parse(token)
 	if err == nil {
 		t.Error("Parse() should fail with different signing key")
 	}
@@ -192,8 +187,7 @@ func TestGenerator_Parse_WrongKey(t *testing.T) {
 func TestGenerator_Parse_Defaults(t *testing.T) {
 	t.Parallel()
 
-	keys, _ := seal.DeriveKeys("test-signing-key-12345")
-	gen := encurl.NewGenerator(keys.EncryptedURLKey)
+	gen, _ := encurl.NewGenerator("test-signing-key-12345")
 
 	// Request with only required fields - should get defaults
 	token, err := gen.Generate(&imagerequest.Request{
@@ -201,12 +195,13 @@ func TestGenerator_Parse_Defaults(t *testing.T) {
 			Host: testSourceHost,
 			Path: testSourcePath,
 		},
-	}, time.Now().Add(time.Hour))
+		Expires: time.Now().Add(time.Hour),
+	})
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}
 
-	req, _, err := gen.Parse(token)
+	req, err := gen.Parse(token)
 	if err != nil {
 		t.Fatalf("Parse() error = %v", err)
 	}
@@ -230,17 +225,17 @@ func TestGenerator_Parse_Defaults(t *testing.T) {
 func TestGenerator_TokenIsURLSafe(t *testing.T) {
 	t.Parallel()
 
-	keys, _ := seal.DeriveKeys("test-signing-key-12345")
-	gen := encurl.NewGenerator(keys.EncryptedURLKey)
+	gen, _ := encurl.NewGenerator("test-signing-key-12345")
 
 	req := &imagerequest.Request{
 		Source: imagerequest.Source{
 			Host: testSourceHost,
 			Path: testSourcePath,
 		},
+		Expires: time.Now().Add(time.Hour),
 	}
 
-	token, _ := gen.Generate(req, time.Now().Add(time.Hour))
+	token, _ := gen.Generate(req)
 
 	// Check that token only contains URL-safe characters
 	for _, c := range token {

internal/handlers/auth.go

@@ -153,20 +153,20 @@ func (s *Handlers) HandleGenerateURL() http.HandlerFunc {
 			return
 		}
 
-		// The image URL must fetch the source URL as it was written. The
-		// fetcher fetches over http only when allow_http is set.
-		fetchURL := req.Source.URL(s.config.AllowHTTP)
+		// The image URL must fetch the source URL as it was written
+		req.AllowHTTP = s.config.AllowHTTP
+		fetchURL := req.SourceURL()
 
 		if !fetchedAsWritten(parsed, fetchURL) {
 			s.renderGeneratorWithForm(w, r, "Source URL cannot be fetched as "+
-				"written: pixa would fetch "+fetchURL.String(),
+				"written: pixa would fetch "+fetchURL,
 				r.Form, http.StatusBadRequest)
 
 			return
 		}
 
 		// Generate encrypted token
-		token, err := s.encGen.Generate(req, expiresAt)
+		token, err := s.encGen.Generate(req)
 		if err != nil {
 			s.log.Error("failed to generate encrypted URL", "error", err)
 			s.renderGeneratorWithForm(w, r, "Failed to generate URL", r.Form,
@@ -226,23 +226,25 @@ func parseSourceURL(sourceURL string) (*url.URL, error) {
 // in RawPath when it is not the decoded path percent-encoded again.
 // EscapedPath ignores RawPath when it also holds a character net/url encodes,
 // such as a space, so RawPath is compared itself.
-func fetchedAsWritten(source, fetchURL *url.URL) bool {
+func fetchedAsWritten(source *url.URL, fetchURL string) bool {
 	writtenPath := source.RawPath
 	if writtenPath == "" {
 		writtenPath = source.EscapedPath()
 	}
 
-	return source.User == nil && !source.ForceQuery &&
-		fetchURL.EscapedPath() == writtenPath &&
-		fetchURL.RawQuery == source.RawQuery
+	fetched, err := url.Parse(fetchURL)
+
+	return err == nil && source.User == nil && !source.ForceQuery &&
+		fetched.EscapedPath() == writtenPath &&
+		fetched.RawQuery == source.RawQuery
 }
 
 // buildGenerateRequest parses the numeric form fields and assembles the
-// image request the encrypted URL's token is made from, and its expiry.
-// ttl=0 means never expires (the expiry is the zero time). A non-numeric or
-// out-of-range width, height, quality or ttl, or an unrecognized fit mode, is
-// a client error naming the offending field. The format field is passed
-// through unchecked.
+// image request the encrypted URL's token is made from. ttl=0 means never
+// expires (Expires stays the zero time). A non-numeric or out-of-range
+// width, height, quality or ttl, or an unrecognized fit mode, is a client
+// error naming the offending field. The format field is passed through
+// unchecked.
 func buildGenerateRequest(
 	parsed *url.URL, form url.Values,
 ) (*imagerequest.Request, time.Time, int, error) {
@@ -292,6 +294,7 @@ func buildGenerateRequest(
 			Quality: quality,
 			FitMode: fitMode,
 		},
+		Expires: expiresAt,
 	}
 
 	return req, expiresAt, ttl, nil

internal/handlers/auth_csrf_internal_test.go

@@ -14,7 +14,6 @@ import (
 
 	"sneak.berlin/go/pixa/internal/config"
 	"sneak.berlin/go/pixa/internal/encurl"
-	"sneak.berlin/go/pixa/internal/seal"
 	"sneak.berlin/go/pixa/internal/session"
 )
 
@@ -45,17 +44,27 @@ func newCSRFTestRouter(t *testing.T) (*Handlers, http.Handler) {
 
 	cfg := &config.Config{SigningKey: testSigningKey, Debug: true}
 
-	keys, err := seal.DeriveKeys(testSigningKey)
+	sessMgr, err := session.NewManager(testSigningKey)
 	if err != nil {
-		t.Fatalf("seal.DeriveKeys() error = %v", err)
+		t.Fatalf("session.NewManager() error = %v", err)
+	}
+
+	encGen, err := encurl.NewGenerator(testSigningKey)
+	if err != nil {
+		t.Fatalf("encurl.NewGenerator() error = %v", err)
+	}
+
+	protect, err := newCSRFProtect(testSigningKey, cfg.Debug)
+	if err != nil {
+		t.Fatalf("newCSRFProtect() error = %v", err)
 	}
 
 	h := &Handlers{
 		log:         slog.New(slog.DiscardHandler),
 		config:      cfg,
-		sessMgr:     session.NewManager(keys.SessionHashKey, keys.SessionBlockKey),
-		encGen:      encurl.NewGenerator(keys.EncryptedURLKey),
-		csrfProtect: newCSRFProtect(keys.CSRFKey, cfg.Debug),
+		sessMgr:     sessMgr,
+		encGen:      encGen,
+		csrfProtect: protect,
 	}
 
 	r := chi.NewRouter()

internal/handlers/auth_login_log_internal_test.go

@@ -10,7 +10,6 @@ import (
 	"testing"
 
 	"sneak.berlin/go/pixa/internal/config"
-	"sneak.berlin/go/pixa/internal/seal"
 	"sneak.berlin/go/pixa/internal/session"
 )
 
@@ -23,15 +22,15 @@ func TestLoginLogLeavesOutSubmittedKey(t *testing.T) {
 
 	var buf bytes.Buffer
 
-	keys, err := seal.DeriveKeys(testSigningKey)
+	sessMgr, err := session.NewManager(testSigningKey)
 	if err != nil {
-		t.Fatalf("seal.DeriveKeys() error = %v", err)
+		t.Fatalf("session.NewManager() error = %v", err)
 	}
 
 	h := &Handlers{
 		log:     slog.New(slog.NewJSONHandler(&buf, nil)),
 		config:  &config.Config{SigningKey: testSigningKey},
-		sessMgr: session.NewManager(keys.SessionHashKey, keys.SessionBlockKey),
+		sessMgr: sessMgr,
 	}
 
 	submittedKeys := []string{wrongKey, testSigningKey}

internal/handlers/auth_session_internal_test.go

@@ -11,7 +11,6 @@ import (
 	"time"
 
 	"sneak.berlin/go/pixa/internal/imagerequest"
-	"sneak.berlin/go/pixa/internal/seal"
 	"sneak.berlin/go/pixa/internal/session"
 )
 
@@ -233,13 +232,8 @@ func TestHandleLogout_SaveFails_Answers500(t *testing.T) {
 
 	db := setupTestDB(t)
 
-	keys, err := seal.DeriveKeys(testSigningKey)
-	if err != nil {
-		t.Fatalf("seal.DeriveKeys() error = %v", err)
-	}
-
 	sessMgr, err := session.NewManagerWithDatabase(
-		t.Context(), keys.SessionHashKey, keys.SessionBlockKey, db)
+		t.Context(), testSigningKey, db)
 	if err != nil {
 		t.Fatalf("session.NewManagerWithDatabase() error = %v", err)
 	}

internal/handlers/avif_too_large_internal_test.go

@@ -12,11 +12,11 @@ import (
 	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
-// TestAVIFOutputTooLargeAnswers400 checks that respondImageError, which
-// answers the errors of both image routes, answers 400 naming the AVIF pixel
-// limit when the image processor refuses an AVIF output above it, wrapped as
-// the service wraps it. The request's source only goes into a log line, so it
-// is left empty.
+// TestAVIFOutputTooLargeAnswers400 checks that respondImageError and
+// handleImageError, which answer the errors of the two image routes, answer
+// 400 naming the AVIF pixel limit when the image processor refuses an AVIF
+// output above it, wrapped as the service wraps it. The request's source only
+// goes into a log line, so it is left empty.
 func TestAVIFOutputTooLargeAnswers400(t *testing.T) {
 	t.Parallel()
 
@@ -25,15 +25,25 @@ func TestAVIFOutputTooLargeAnswers400(t *testing.T) {
 		imageprocessor.ErrAVIFOutputTooLarge)
 	wantBody := fmt.Sprintf("above %d pixels", imageprocessor.MaxAVIFOutputPixels)
 
-	rec := httptest.NewRecorder()
-	h.respondImageError(rec, &imagerequest.Request{}, err)
-	t.Logf("status = %d, body = %q", rec.Code, rec.Body.String())
+	plain := httptest.NewRecorder()
+	h.respondImageError(plain, &imagerequest.Request{}, err)
 
-	if rec.Code != http.StatusBadRequest {
-		t.Errorf("status = %d, want %d", rec.Code, http.StatusBadRequest)
-	}
+	encrypted := httptest.NewRecorder()
+	h.handleImageError(encrypted, err)
 
-	if !strings.Contains(rec.Body.String(), wantBody) {
-		t.Errorf("body = %q, want it to say %q", rec.Body.String(), wantBody)
+	for name, rec := range map[string]*httptest.ResponseRecorder{
+		"respondImageError": plain, "handleImageError": encrypted,
+	} {
+		t.Logf("%s: status = %d, body = %q", name, rec.Code, rec.Body.String())
+
+		if rec.Code != http.StatusBadRequest {
+			t.Errorf("%s: status = %d, want %d",
+				name, rec.Code, http.StatusBadRequest)
+		}
+
+		if !strings.Contains(rec.Body.String(), wantBody) {
+			t.Errorf("%s: body = %q, want it to say %q",
+				name, rec.Body.String(), wantBody)
+		}
 	}
 }

internal/handlers/bodylimit_internal_test.go

@@ -11,7 +11,6 @@ import (
 
 	"sneak.berlin/go/pixa/internal/config"
 	"sneak.berlin/go/pixa/internal/encurl"
-	"sneak.berlin/go/pixa/internal/seal"
 	"sneak.berlin/go/pixa/internal/session"
 )
 
@@ -33,17 +32,27 @@ func newBodyLimitTestRouter(
 
 	cfg := &config.Config{SigningKey: testSigningKey, Debug: true}
 
-	keys, err := seal.DeriveKeys(testSigningKey)
+	sessMgr, err := session.NewManager(testSigningKey)
 	if err != nil {
-		t.Fatalf("seal.DeriveKeys() error = %v", err)
+		t.Fatalf("session.NewManager() error = %v", err)
+	}
+
+	encGen, err := encurl.NewGenerator(testSigningKey)
+	if err != nil {
+		t.Fatalf("encurl.NewGenerator() error = %v", err)
+	}
+
+	protect, err := newCSRFProtect(testSigningKey, cfg.Debug)
+	if err != nil {
+		t.Fatalf("newCSRFProtect() error = %v", err)
 	}
 
 	h := &Handlers{
 		log:         slog.New(slog.DiscardHandler),
 		config:      cfg,
-		sessMgr:     session.NewManager(keys.SessionHashKey, keys.SessionBlockKey),
-		encGen:      encurl.NewGenerator(keys.EncryptedURLKey),
-		csrfProtect: newCSRFProtect(keys.CSRFKey, cfg.Debug),
+		sessMgr:     sessMgr,
+		encGen:      encGen,
+		csrfProtect: protect,
 	}
 
 	r := chi.NewRouter()

internal/handlers/cache_hit_internal_test.go

@@ -17,17 +17,11 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/v5"
-	"github.com/prometheus/client_golang/prometheus"
 
-	"sneak.berlin/go/pixa/internal/allowlist"
 	"sneak.berlin/go/pixa/internal/database"
 	"sneak.berlin/go/pixa/internal/encurl"
-	"sneak.berlin/go/pixa/internal/imageprocessor"
-	"sneak.berlin/go/pixa/internal/imageproxy"
 	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/imgcache"
-	"sneak.berlin/go/pixa/internal/seal"
-	"sneak.berlin/go/pixa/internal/signature"
 )
 
 // countingHost is the allowlisted host whose photoPath the server of
@@ -107,8 +101,9 @@ func newCountingDatabase(tb testing.TB) (*sql.DB, *atomic.Int64) {
 // newCountingDatabaseServer returns a router for both image routes whose
 // image cache uses newCountingDatabase, the count of the statements run on
 // that database, and a URL on each route for a different image of
-// photoPath on countingHost. Nothing writes the cache's access times in the
-// background, so every statement counted comes from a request.
+// photoPath on countingHost. Nothing writes the cache's pending counts and
+// access times in the background, so every statement counted comes from a
+// request.
 func newCountingDatabaseServer(
 	tb testing.TB,
 ) (http.Handler, *atomic.Int64, []string) {
@@ -123,38 +118,32 @@ func newCountingDatabaseServer(
 		tb.Fatalf("encoding the photo: %v", err)
 	}
 
-	cache, err := imgcache.NewCache(db, imgcache.Config{
+	cache, err := imgcache.NewCache(db, imgcache.CacheConfig{
 		StateDir:    tb.TempDir(),
 		NegativeTTL: 5 * time.Minute,
-		MaxBytes:    1 << 30,
-	}, prometheus.NewRegistry())
+	})
 	if err != nil {
 		tb.Fatalf("imgcache.NewCache() error = %v", err)
 	}
 
-	svc, err := imageproxy.New(&imageproxy.Config{
+	svc, err := imgcache.NewService(&imgcache.ServiceConfig{
 		Cache: cache,
 		Fetcher: newMockFetcher(fstest.MapFS{
 			countingHost + photoPath: &fstest.MapFile{Data: photo.Bytes()},
 		}),
-		Processor: imageprocessor.New(imageprocessor.Params{
-			MaxInputBytes:           50 << 20,
-			MaxConcurrentProcessing: 2,
-		}),
-		MaxResponseSize: 50 << 20,
-		Logger:          slog.New(slog.DiscardHandler),
-	}, prometheus.NewRegistry())
+		SigningKey: testSigningKey,
+		Allowlist:  []string{countingHost},
+		Logger:     slog.New(slog.DiscardHandler),
+	})
 	if err != nil {
-		tb.Fatalf("imageproxy.New() error = %v", err)
+		tb.Fatalf("imgcache.NewService() error = %v", err)
 	}
 
-	keys, err := seal.DeriveKeys(testSigningKey)
+	encGen, err := encurl.NewGenerator(testSigningKey)
 	if err != nil {
-		tb.Fatalf("seal.DeriveKeys() error = %v", err)
+		tb.Fatalf("encurl.NewGenerator() error = %v", err)
 	}
 
-	encGen := encurl.NewGenerator(keys.EncryptedURLKey)
-
 	token, err := encGen.Generate(&imagerequest.Request{
 		Source: imagerequest.Source{Host: countingHost, Path: photoPath},
 		Transform: imagerequest.Transform{
@@ -163,17 +152,15 @@ func newCountingDatabaseServer(
 			Quality: 85,
 			FitMode: imagerequest.FitCover,
 		},
-	}, time.Time{})
+	})
 	if err != nil {
 		tb.Fatalf("encGen.Generate() error = %v", err)
 	}
 
 	h := &Handlers{
-		log:       slog.New(slog.DiscardHandler),
-		imgSvc:    svc,
-		encGen:    encGen,
-		signer:    signature.New(testSigningKey),
-		allowlist: allowlist.New([]string{countingHost}),
+		log:    slog.New(slog.DiscardHandler),
+		imgSvc: svc,
+		encGen: encGen,
 	}
 
 	r := chi.NewRouter()
@@ -229,9 +216,9 @@ func TestImageRoutes_CacheHitsMakeNoDatabaseCall(t *testing.T) {
 			rec := serveImage(t, srv, target)
 
 			cacheStatus := rec.Header().Get("X-Pixa-Cache")
-			if cacheStatus != string(imageproxy.CacheHit) {
+			if cacheStatus != string(imgcache.CacheHit) {
 				t.Errorf("GET %s: X-Pixa-Cache = %q, want %s",
-					target, cacheStatus, imageproxy.CacheHit)
+					target, cacheStatus, imgcache.CacheHit)
 			}
 		}
 
@@ -261,9 +248,9 @@ func BenchmarkHandleImage_CacheHits(b *testing.B) {
 			rec := serveImage(b, srv, target)
 
 			cacheStatus := rec.Header().Get("X-Pixa-Cache")
-			if cacheStatus != string(imageproxy.CacheHit) {
+			if cacheStatus != string(imgcache.CacheHit) {
 				b.Errorf("GET %s: X-Pixa-Cache = %q, want %s",
-					target, cacheStatus, imageproxy.CacheHit)
+					target, cacheStatus, imgcache.CacheHit)
 
 				return
 			}

internal/handlers/cache_max_bytes_internal_test.go

@@ -0,0 +1,147 @@
+package handlers
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"go.uber.org/fx/fxtest"
+
+	"sneak.berlin/go/pixa/internal/config"
+	"sneak.berlin/go/pixa/internal/database"
+	"sneak.berlin/go/pixa/internal/globals"
+	"sneak.berlin/go/pixa/internal/logger"
+)
+
+// TestNewCacheConfigFromCacheMaxBytes checks the cache configuration
+// built from cache_max_bytes: omitted, the cache works out the default
+// limit; 0 turns the disk cache off; a positive value is the limit,
+// unchanged.
+func TestNewCacheConfigFromCacheMaxBytes(t *testing.T) {
+	t.Parallel()
+
+	const oneGiB = 1 << 30
+
+	cases := []struct {
+		name                   string
+		cacheMaxBytes          int64
+		cacheMaxBytesExplicit  bool
+		wantMaxBytes           int64
+		wantUseDefaultMaxBytes bool
+		wantDisableDiskCache   bool
+	}{
+		{
+			name:                   "cache_max_bytes omitted",
+			cacheMaxBytes:          0,
+			cacheMaxBytesExplicit:  false,
+			wantMaxBytes:           0,
+			wantUseDefaultMaxBytes: true,
+			wantDisableDiskCache:   false,
+		},
+		{
+			name:                   "cache_max_bytes: 0",
+			cacheMaxBytes:          0,
+			cacheMaxBytesExplicit:  true,
+			wantMaxBytes:           0,
+			wantUseDefaultMaxBytes: false,
+			wantDisableDiskCache:   true,
+		},
+		{
+			name:                   "cache_max_bytes: 1 GiB",
+			cacheMaxBytes:          oneGiB,
+			cacheMaxBytesExplicit:  true,
+			wantMaxBytes:           oneGiB,
+			wantUseDefaultMaxBytes: false,
+			wantDisableDiskCache:   false,
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			cfg := &config.Config{
+				CacheMaxBytes:         tc.cacheMaxBytes,
+				CacheMaxBytesExplicit: tc.cacheMaxBytesExplicit,
+			}
+
+			got := newCacheConfig(cfg, nil)
+			t.Logf("MaxBytes = %d, UseDefaultMaxBytes = %v, DisableDiskCache = %v",
+				got.MaxBytes, got.UseDefaultMaxBytes, got.DisableDiskCache)
+
+			if got.MaxBytes != tc.wantMaxBytes {
+				t.Errorf("MaxBytes = %d, want %d", got.MaxBytes, tc.wantMaxBytes)
+			}
+
+			if got.UseDefaultMaxBytes != tc.wantUseDefaultMaxBytes {
+				t.Errorf("UseDefaultMaxBytes = %v, want %v",
+					got.UseDefaultMaxBytes, tc.wantUseDefaultMaxBytes)
+			}
+
+			if got.DisableDiskCache != tc.wantDisableDiskCache {
+				t.Errorf("DisableDiskCache = %v, want %v",
+					got.DisableDiskCache, tc.wantDisableDiskCache)
+			}
+		})
+	}
+}
+
+// TestDiskCacheOffOnlyForExplicitZeroCacheMaxBytes starts the handlers
+// once with cache_max_bytes omitted and once with cache_max_bytes: 0,
+// and checks by whether the cache directories were created that the
+// disk cache is on in the first case and off in the second.
+func TestDiskCacheOffOnlyForExplicitZeroCacheMaxBytes(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name                  string
+		cacheMaxBytesExplicit bool
+		wantDiskCache         bool
+	}{
+		{name: "cache_max_bytes omitted", cacheMaxBytesExplicit: false, wantDiskCache: true},
+		{name: "cache_max_bytes: 0", cacheMaxBytesExplicit: true, wantDiskCache: false},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			stateDir := t.TempDir()
+			cfg := &config.Config{
+				SigningKey:            testSigningKey,
+				StateDir:              stateDir,
+				DBURL:                 "file:" + filepath.Join(stateDir, "state.sqlite3"),
+				CacheMaxBytes:         0,
+				CacheMaxBytesExplicit: tc.cacheMaxBytesExplicit,
+			}
+
+			lc := fxtest.NewLifecycle(t)
+
+			log, err := logger.New(lc, logger.Params{Globals: &globals.Globals{}})
+			if err != nil {
+				t.Fatalf("logger.New() error = %v", err)
+			}
+
+			db, err := database.New(lc, database.Params{Logger: log, Config: cfg})
+			if err != nil {
+				t.Fatalf("database.New() error = %v", err)
+			}
+
+			_, err = New(lc, Params{Logger: log, Database: db, Config: cfg})
+			if err != nil {
+				t.Fatalf("New() error = %v", err)
+			}
+
+			lc.RequireStart()
+			t.Cleanup(lc.RequireStop)
+
+			_, err = os.Stat(filepath.Join(stateDir, "cache", "variants"))
+			gotDiskCache := err == nil
+
+			if gotDiskCache != tc.wantDiskCache {
+				t.Errorf("cache directories created = %v, want %v",
+					gotDiskCache, tc.wantDiskCache)
+			}
+		})
+	}
+}

internal/handlers/client_gone_internal_test.go

@@ -1,177 +0,0 @@
-package handlers
-
-import (
-	"bytes"
-	"context"
-	"encoding/json"
-	"log/slog"
-	"net/http"
-	"net/http/httptest"
-	"slices"
-	"testing"
-	"time"
-
-	"github.com/go-chi/chi/v5/middleware"
-	"sneak.berlin/go/pixa/internal/httpfetcher"
-	"sneak.berlin/go/pixa/internal/imagerequest"
-)
-
-// heldFetcher sends on started when a fetch begins, and holds the fetch until
-// release is closed. It then fails the fetch as an upstream error.
-type heldFetcher struct {
-	started chan struct{}
-	release chan struct{}
-}
-
-// Fetch sends on f.started, waits for f.release to be closed, and returns
-// httpfetcher.ErrUpstreamError.
-func (f heldFetcher) Fetch(
-	context.Context, imagerequest.Source,
-) (*httpfetcher.FetchResult, error) {
-	f.started <- struct{}{}
-
-	<-f.release
-
-	return nil, httpfetcher.ErrUpstreamError
-}
-
-// readLogLines decodes the JSON log lines in logs.
-func readLogLines(t *testing.T, logs *bytes.Buffer) []map[string]any {
-	t.Helper()
-
-	t.Logf("logged:\n%s", logs.String())
-
-	var lines []map[string]any
-
-	dec := json.NewDecoder(logs)
-	for dec.More() {
-		var line map[string]any
-
-		err := dec.Decode(&line)
-		if err != nil {
-			t.Fatalf("decoding log line: %v", err)
-		}
-
-		lines = append(lines, line)
-	}
-
-	return lines
-}
-
-// TestImageRoutes_ClientGoneWhileWaitingAnswers499 checks that both image
-// routes answer 499 to a request whose client goes away while it waits for an
-// image another request is making. A first request's fetch is held, so the
-// image is being made, and a second request for the same image waits for it
-// until its client goes away. The second request must be logged once at info
-// level with its request ID and the source host and path. Nothing may be
-// logged at error level.
-func TestImageRoutes_ClientGoneWhileWaitingAnswers499(t *testing.T) {
-	t.Parallel()
-
-	const requestID = "test-request-id"
-
-	for route, imageURL := range photoURLsByRoute() {
-		t.Run(route, func(t *testing.T) {
-			t.Parallel()
-
-			var logs bytes.Buffer
-
-			fetcher := heldFetcher{started: make(chan struct{}), release: make(chan struct{})}
-			h, routes := newRoutesFetchingThrough(t, fetcher,
-				slog.New(slog.NewJSONHandler(&logs, nil)))
-			target := imageURL(t, h)
-
-			firstDone := make(chan struct{})
-
-			go func() {
-				defer close(firstDone)
-
-				sendGet(t, routes, target)
-			}()
-
-			<-fetcher.started
-
-			ctx, cancel := context.WithCancel(context.WithValue(t.Context(),
-				middleware.RequestIDKey, requestID))
-			rec := httptest.NewRecorder()
-			secondDone := make(chan struct{})
-
-			go func() {
-				defer close(secondDone)
-
-				routes.ServeHTTP(rec, httptest.NewRequestWithContext(
-					ctx, http.MethodGet, target, nil))
-			}()
-
-			// Give the second request time to start waiting for the first
-			// request's image. The fetch is still held, so the second request
-			// can end only because its client went away
-			time.Sleep(100 * time.Millisecond)
-			cancel()
-			<-secondDone
-
-			close(fetcher.release)
-			<-firstDone
-
-			if rec.Code != 499 {
-				t.Errorf("status = %d, want 499", rec.Code)
-			}
-
-			var clientGoneLines int
-
-			for _, line := range readLogLines(t, &logs) {
-				if line["level"] == slog.LevelError.String() {
-					t.Errorf("logged at error level: %v", line["msg"])
-				}
-
-				if line["level"] == slog.LevelInfo.String() &&
-					line["msg"] == "client went away before the image was ready" &&
-					line["request_id"] == requestID &&
-					line["host"] == signedHost &&
-					line["path"] == photoPath {
-					clientGoneLines++
-				}
-			}
-
-			if clientGoneLines != 1 {
-				t.Errorf("info line naming the request logged %d times, want 1",
-					clientGoneLines)
-			}
-		})
-	}
-}
-
-// TestImageRoutes_CanceledWithLiveRequestAnswers500 checks that both image
-// routes answer 500, logged as "failed to get image" at error level, for an
-// image service error that wraps context.Canceled while the request's own
-// context is live. Its client has not gone away, so the cancellation is
-// pixa's own failure.
-func TestImageRoutes_CanceledWithLiveRequestAnswers500(t *testing.T) {
-	t.Parallel()
-
-	for route, imageURL := range photoURLsByRoute() {
-		t.Run(route, func(t *testing.T) {
-			t.Parallel()
-
-			var logs bytes.Buffer
-
-			h, routes := newRoutesFetchingThrough(t,
-				failingFetcher{err: context.Canceled},
-				slog.New(slog.NewJSONHandler(&logs, nil)))
-
-			rec := sendGet(t, routes, imageURL(t, h))
-			if rec.Code != http.StatusInternalServerError {
-				t.Errorf("status = %d, want %d",
-					rec.Code, http.StatusInternalServerError)
-			}
-
-			if !slices.ContainsFunc(readLogLines(t, &logs),
-				func(line map[string]any) bool {
-					return line["level"] == slog.LevelError.String() &&
-						line["msg"] == "failed to get image"
-				}) {
-				t.Error(`no "failed to get image" line logged at error level`)
-			}
-		})
-	}
-}

internal/handlers/csrf.go

@@ -9,10 +9,15 @@ import (
 	"sneak.berlin/go/pixa/internal/seal"
 )
 
+// csrfKeySalt provides domain separation for the CSRF authentication key,
+// derived from the signing key so tokens survive restarts without extra
+// configuration and never reuse the session or encrypted-URL key material.
+const csrfKeySalt = "pixa-csrf-v1"
+
 // newCSRFProtect builds the CSRF-protection middleware for the
 // state-mutating HTML form routes. The token lives in its own cookie,
 // independent of the session cookie, so it also protects the login POST
-// where no session exists yet (login CSRF). key signs that cookie.
+// where no session exists yet (login CSRF).
 //
 // When plaintext is true (local HTTP development), requests are marked
 // plaintext so the library neither demands an https Referer nor sets a
@@ -20,8 +25,13 @@ import (
 // service runs behind a TLS-terminating proxy, so plaintext is false and
 // the library enforces its https Referer origin check.
 func newCSRFProtect(
-	key [seal.KeySize]byte, plaintext bool,
-) func(http.Handler) http.Handler {
+	signingKey string, plaintext bool,
+) (func(http.Handler) http.Handler, error) {
+	key, err := seal.DeriveKey([]byte(signingKey), csrfKeySalt)
+	if err != nil {
+		return nil, err
+	}
+
 	protect := csrf.Protect(
 		key[:],
 		csrf.Path("/"),
@@ -30,7 +40,7 @@ func newCSRFProtect(
 	)
 
 	if !plaintext {
-		return protect
+		return protect, nil
 	}
 
 	return func(next http.Handler) http.Handler {
@@ -39,7 +49,7 @@ func newCSRFProtect(
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			protected.ServeHTTP(w, csrf.PlaintextHTTPRequest(r))
 		})
-	}
+	}, nil
 }
 
 // CSRF returns the CSRF-protection middleware for the login and generator

internal/handlers/fetcher_internal_test.go

@@ -0,0 +1,61 @@
+package handlers
+
+import (
+	"net/http"
+	"net/netip"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/go-chi/chi/v5"
+	"go.uber.org/fx"
+	"go.uber.org/fx/fxtest"
+
+	"sneak.berlin/go/pixa/internal/config"
+	"sneak.berlin/go/pixa/internal/database"
+	"sneak.berlin/go/pixa/internal/globals"
+	"sneak.berlin/go/pixa/internal/healthcheck"
+	"sneak.berlin/go/pixa/internal/logger"
+)
+
+// TestHandlersBuildTheirOwnFetcherWhenNoneIsProvided builds the handlers as
+// pixad does, in an fx app that provides no fetcher, and requests an image
+// from 192.0.2.10, which is on the allowlist and in blocked_networks. The URL
+// check accepts that address; only the dialer that refuses internal
+// addresses checks blocked_networks, so the answer is 403 only if the
+// fetcher the handlers build from the config connects with that dialer. Any
+// other dialer would try to connect until the upstream fetch timeout, which
+// is short so that the test then fails quickly.
+func TestHandlersBuildTheirOwnFetcherWhenNoneIsProvided(t *testing.T) {
+	t.Parallel()
+
+	const host = "192.0.2.10"
+
+	stateDir := t.TempDir()
+	cfg := &config.Config{
+		SigningKey:           testSigningKey,
+		StateDir:             stateDir,
+		DBURL:                "file:" + filepath.Join(stateDir, "state.sqlite3"),
+		AllowlistHosts:       []string{host},
+		BlockedNetworks:      []netip.Prefix{netip.MustParsePrefix("192.0.2.0/24")},
+		UpstreamFetchTimeout: 2 * time.Second,
+		// With no connection slots, the fetch would fail before dialing.
+		UpstreamConnections: config.DefaultUpstreamConnections,
+	}
+
+	var h *Handlers
+
+	app := fxtest.New(t,
+		fx.Supply(cfg),
+		fx.Provide(globals.New, logger.New, database.New, healthcheck.New, New),
+		fx.Populate(&h),
+	)
+	app.RequireStart()
+	t.Cleanup(app.RequireStop)
+
+	r := chi.NewRouter()
+	r.Get("/v1/image/*", h.HandleImage())
+
+	rec := sendGet(t, r, photoURL(host))
+	checkErrorBody(t, rec, http.StatusForbidden, "forbidden")
+}

internal/handlers/first_bytes_internal_test.go

@@ -12,16 +12,10 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/v5"
-	"github.com/prometheus/client_golang/prometheus"
-	"sneak.berlin/go/pixa/internal/allowlist"
 	"sneak.berlin/go/pixa/internal/encurl"
 	"sneak.berlin/go/pixa/internal/httpfetcher"
-	"sneak.berlin/go/pixa/internal/imageprocessor"
-	"sneak.berlin/go/pixa/internal/imageproxy"
 	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/imgcache"
-	"sneak.berlin/go/pixa/internal/seal"
-	"sneak.berlin/go/pixa/internal/signature"
 )
 
 // mismatchedSourcePath is the path of the source that
@@ -31,51 +25,38 @@ import (
 const mismatchedSourcePath = "/images/source.png"
 
 // newRoutesFetchingThrough returns both image routes, and the Handlers behind
-// them, whose image service fetches through fetcher, and which have
-// allowlistedHost on their allowlist. The handlers and the image service log
-// to log.
+// them, whose image service fetches through fetcher and has allowlistedHost on
+// its allowlist. The handlers and the image service log to log.
 func newRoutesFetchingThrough(
 	t *testing.T, fetcher httpfetcher.Fetcher, log *slog.Logger,
 ) (*Handlers, http.Handler) {
 	t.Helper()
 
-	cache, err := imgcache.NewCache(setupTestDB(t), imgcache.Config{
+	cache, err := imgcache.NewCache(setupTestDB(t), imgcache.CacheConfig{
 		StateDir:    t.TempDir(),
 		NegativeTTL: 5 * time.Minute,
-		MaxBytes:    1 << 30,
-	}, prometheus.NewRegistry())
+	})
 	if err != nil {
 		t.Fatalf("imgcache.NewCache() error = %v", err)
 	}
 
-	svc, err := imageproxy.New(&imageproxy.Config{
-		Cache:   cache,
-		Fetcher: fetcher,
-		Processor: imageprocessor.New(imageprocessor.Params{
-			MaxInputBytes:           50 << 20,
-			MaxConcurrentProcessing: 2,
-		}),
-		MaxResponseSize: 50 << 20,
-		Logger:          log,
-	}, prometheus.NewRegistry())
+	svc, err := imgcache.NewService(&imgcache.ServiceConfig{
+		Cache:      cache,
+		Fetcher:    fetcher,
+		SigningKey: testSigningKey,
+		Allowlist:  []string{allowlistedHost},
+		Logger:     log,
+	})
 	if err != nil {
-		t.Fatalf("imageproxy.New() error = %v", err)
+		t.Fatalf("imgcache.NewService() error = %v", err)
 	}
 
-	keys, err := seal.DeriveKeys(testSigningKey)
+	encGen, err := encurl.NewGenerator(testSigningKey)
 	if err != nil {
-		t.Fatalf("seal.DeriveKeys() error = %v", err)
+		t.Fatalf("encurl.NewGenerator() error = %v", err)
 	}
 
-	encGen := encurl.NewGenerator(keys.EncryptedURLKey)
-
-	h := &Handlers{
-		log:       log,
-		imgSvc:    svc,
-		encGen:    encGen,
-		signer:    signature.New(testSigningKey),
-		allowlist: allowlist.New([]string{allowlistedHost}),
-	}
+	h := &Handlers{log: log, imgSvc: svc, encGen: encGen}
 
 	r := chi.NewRouter()
 	r.Get("/v1/image/*", h.HandleImage())
@@ -104,7 +85,7 @@ func mismatchedSourceEncURL(t *testing.T, h *Handlers) string {
 			Size:   imagerequest.Size{Width: 50, Height: 50},
 			Format: imagerequest.FormatJPEG,
 		},
-	}, time.Time{})
+	})
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}

internal/handlers/format_auto.go

@@ -18,17 +18,16 @@ var (
 		"image/jxl, image/avif, image/webp or image/jpeg")
 )
 
-// chooseAutoFormat returns the format to serve for the requested format: for
-// the format auto, the format formatForAccept chooses from r's Accept header,
-// and any other format as it is. For auto it adds Vary: Accept to the
+// chooseAutoFormat replaces the format auto in req with the format
+// formatForAccept chooses from r's Accept header, and adds Vary: Accept to the
 // response, which then depends on that header. It answers 400 for an Accept
 // header that is not valid and 406 for one that allows none of the formats,
-// and reports whether the image can be served.
+// and reports whether req can be served. Any other format is left as it is.
 func (s *Handlers) chooseAutoFormat(
-	w http.ResponseWriter, r *http.Request, requested imagerequest.Format,
-) (imagerequest.Format, bool) {
-	if requested != imagerequest.FormatAuto {
-		return requested, true
+	w http.ResponseWriter, r *http.Request, req *imagerequest.Request,
+) bool {
+	if req.Transform.Format != imagerequest.FormatAuto {
+		return true
 	}
 
 	w.Header().Add("Vary", "Accept")
@@ -37,16 +36,18 @@ func (s *Handlers) chooseAutoFormat(
 	if errors.Is(err, errNotAcceptable) {
 		s.respondError(w, err.Error(), http.StatusNotAcceptable)
 
-		return "", false
+		return false
 	}
 
 	if err != nil {
 		s.respondError(w, err.Error(), http.StatusBadRequest)
 
-		return "", false
+		return false
 	}
 
-	return format, true
+	req.Transform.Format = format
+
+	return true
 }
 
 // formatForAccept returns the format an auto URL is served in for the Accept
@@ -65,20 +66,20 @@ func formatForAccept(accept string) (imagerequest.Format, error) {
 		return imagerequest.FormatJPEG, nil
 	}
 
-	if qualities[imagerequest.FormatJXL.MIMEType()] > 0 {
+	if qualities["image/jxl"] > 0 {
 		return imagerequest.FormatJXL, nil
 	}
 
-	if qualities[imagerequest.FormatAVIF.MIMEType()] > 0 {
+	if qualities["image/avif"] > 0 {
 		return imagerequest.FormatAVIF, nil
 	}
 
-	if qualities[imagerequest.FormatWebP.MIMEType()] > 0 {
+	if qualities["image/webp"] > 0 {
 		return imagerequest.FormatWebP, nil
 	}
 
 	// For JPEG, the most specific entry the header has decides
-	quality, named := qualities[imagerequest.FormatJPEG.MIMEType()]
+	quality, named := qualities["image/jpeg"]
 	if !named {
 		quality, named = qualities["image/*"]
 	}

internal/handlers/format_auto_internal_test.go

@@ -75,13 +75,11 @@ func TestFormatForAccept(t *testing.T) {
 
 // autoPhotoURLs returns a signed /v1/image/ URL and an encrypted /v1/e/ URL,
 // both valid for a minute, for the JPEG at photoPath on signedHost at 50x50 in
-// the format auto. The first is signed with testSigningKey, the key the
-// handlers that newSignedHostServer builds check signatures with. The second
-// is made with h's generator.
+// the format auto, made with h's image service and generator.
 func autoPhotoURLs(t *testing.T, h *Handlers) (string, string) {
 	t.Helper()
 
-	signedURL := generateSignedURL(testSigningKey, &imagerequest.Request{
+	signedURL, err := h.imgSvc.GenerateSignedURL("", &imagerequest.Request{
 		Source: imagerequest.Source{
 			Host: signedHost,
 			Path: photoPath,
@@ -91,6 +89,9 @@ func autoPhotoURLs(t *testing.T, h *Handlers) (string, string) {
 			Format: imagerequest.FormatAuto,
 		},
 	}, time.Minute)
+	if err != nil {
+		t.Fatalf("GenerateSignedURL() error = %v", err)
+	}
 
 	token, err := h.encGen.Generate(&imagerequest.Request{
 		Source: imagerequest.Source{
@@ -101,7 +102,8 @@ func autoPhotoURLs(t *testing.T, h *Handlers) (string, string) {
 			Size:   imagerequest.Size{Width: 50, Height: 50},
 			Format: imagerequest.FormatAuto,
 		},
-	}, time.Now().Add(time.Minute))
+		Expires: time.Now().Add(time.Minute),
+	})
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}
@@ -186,9 +188,9 @@ func TestFormatAuto_ChosenFromAccept(t *testing.T) {
 func TestFormatAuto_SignatureCoversAuto(t *testing.T) {
 	t.Parallel()
 
-	_, srv := newSignedHostServer(t, slog.New(slog.DiscardHandler))
+	h, srv := newSignedHostServer(t, slog.New(slog.DiscardHandler))
 
-	signedForAVIF := generateSignedURL(testSigningKey, &imagerequest.Request{
+	signedForAVIF, err := h.imgSvc.GenerateSignedURL("", &imagerequest.Request{
 		Source: imagerequest.Source{
 			Host: signedHost,
 			Path: photoPath,
@@ -198,6 +200,9 @@ func TestFormatAuto_SignatureCoversAuto(t *testing.T) {
 			Format: imagerequest.FormatAVIF,
 		},
 	}, time.Minute)
+	if err != nil {
+		t.Fatalf("GenerateSignedURL() error = %v", err)
+	}
 
 	target := strings.Replace(signedForAVIF, "/50x50.avif?", "/50x50.auto?", 1)
 	if target == signedForAVIF {

internal/handlers/handlers.go

@@ -4,6 +4,7 @@ package handlers
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"log/slog"
 	"net/http"
 	"time"
@@ -11,13 +12,13 @@ import (
 	"go.uber.org/fx"
 	"sneak.berlin/go/pixa/internal/allowlist"
 	"sneak.berlin/go/pixa/internal/config"
+	"sneak.berlin/go/pixa/internal/database"
 	"sneak.berlin/go/pixa/internal/encurl"
 	"sneak.berlin/go/pixa/internal/healthcheck"
-	"sneak.berlin/go/pixa/internal/imageproxy"
+	"sneak.berlin/go/pixa/internal/httpfetcher"
+	"sneak.berlin/go/pixa/internal/imgcache"
 	"sneak.berlin/go/pixa/internal/logger"
-	"sneak.berlin/go/pixa/internal/seal"
 	"sneak.berlin/go/pixa/internal/session"
-	"sneak.berlin/go/pixa/internal/signature"
 )
 
 // Params defines dependencies for Handlers.
@@ -26,48 +27,70 @@ type Params struct {
 
 	Logger      *logger.Logger
 	Healthcheck *healthcheck.Healthcheck
+	Database    *database.Database
 	Config      *config.Config
-	Keys        seal.Keys
 
-	ImageService          *imageproxy.Proxy
-	SessionManager        *session.Manager
-	EncryptedURLGenerator *encurl.Generator
+	// Fetcher, when provided, fetches upstream images in place of the
+	// fetcher the handlers build from the config. Only tests provide one;
+	// pixad does not.
+	Fetcher httpfetcher.Fetcher `optional:"true"`
 }
 
 // Handlers provides HTTP request handlers.
 type Handlers struct {
 	log         *slog.Logger
 	hc          *healthcheck.Healthcheck
+	db          *database.Database
 	config      *config.Config
-	imgSvc      *imageproxy.Proxy
+	fetcher     httpfetcher.Fetcher
+	imgSvc      *imgcache.Service
+	imgCache    *imgcache.Cache
 	sessMgr     *session.Manager
 	encGen      *encurl.Generator
 	csrfProtect func(http.Handler) http.Handler
 
-	// signer checks the signature of a /v1/image/ URL with signing_key.
-	signer *signature.Signer
-	// allowlist matches the hosts of allowlist_hosts, which a /v1/image/
-	// URL may name without a signature.
-	allowlist *allowlist.HostAllowList
 	// refererBlocklist matches the hosts of referer_blocklist; its IsAllowed
 	// reports whether a URL's host is on that list.
 	refererBlocklist *allowlist.HostAllowList
 }
 
 // New creates a new Handlers instance.
-func New(_ fx.Lifecycle, params Params) *Handlers {
-	return &Handlers{
+func New(lc fx.Lifecycle, params Params) (*Handlers, error) {
+	csrfProtect, err := newCSRFProtect(params.Config.SigningKey, params.Config.Debug)
+	if err != nil {
+		return nil, err
+	}
+
+	s := &Handlers{
 		log:              params.Logger.Get(),
 		hc:               params.Healthcheck,
+		db:               params.Database,
 		config:           params.Config,
-		imgSvc:           params.ImageService,
-		sessMgr:          params.SessionManager,
-		encGen:           params.EncryptedURLGenerator,
-		csrfProtect:      newCSRFProtect(params.Keys.CSRFKey, params.Config.Debug),
-		signer:           signature.New(params.Config.SigningKey),
-		allowlist:        allowlist.New(params.Config.AllowlistHosts),
+		fetcher:          params.Fetcher,
+		csrfProtect:      csrfProtect,
 		refererBlocklist: allowlist.New(params.Config.RefererBlocklist),
 	}
+
+	lc.Append(fx.Hook{
+		//nolint:contextcheck // the cache's goroutines outlive OnStart; OnStop stops them
+		OnStart: func(_ context.Context) error {
+			return s.initImageService()
+		},
+		// The pending counts and access times are written here, before the
+		// database's stop hook closes it.
+		OnStop: func(ctx context.Context) error {
+			if s.imgCache == nil {
+				return nil
+			}
+
+			return errors.Join(
+				s.imgCache.StopEviction(ctx),
+				s.imgCache.StopPendingCountWrites(ctx),
+			)
+		},
+	})
+
+	return s, nil
 }
 
 // WaitForProcessing waits until no image is being processed, or until ctx
@@ -76,6 +99,95 @@ func (s *Handlers) WaitForProcessing(ctx context.Context) int {
 	return s.imgSvc.WaitForProcessing(ctx)
 }
 
+// newCacheConfig builds the image cache's configuration from cfg.
+// cache_max_bytes: 0 disables the disk cache entirely; any other value
+// is the eviction limit in bytes; when it is omitted, the cache works
+// out the default limit itself.
+func newCacheConfig(cfg *config.Config, log *slog.Logger) imgcache.CacheConfig {
+	return imgcache.CacheConfig{
+		StateDir:           cfg.StateDir,
+		NegativeTTL:        imgcache.DefaultNegativeTTL,
+		MaxBytes:           cfg.CacheMaxBytes,
+		UseDefaultMaxBytes: !cfg.CacheMaxBytesExplicit,
+		DisableDiskCache:   cfg.CacheMaxBytesExplicit && cfg.CacheMaxBytes == 0,
+		Logger:             log,
+	}
+}
+
+// initImageService initializes the image cache and service.
+func (s *Handlers) initImageService() error {
+	cache, err := imgcache.NewCache(s.db.DB(), newCacheConfig(s.config, s.log))
+	if err != nil {
+		return err
+	}
+
+	s.imgCache = cache
+
+	// Background eviction: startup reconciliation, then periodic and
+	// write-pressure passes, and the removal of expired negative cache
+	// rows, which is all it does when the disk cache is disabled.
+	cache.StartEviction(imgcache.DefaultEvictionInterval)
+
+	// Writes the counts and the access times of cache hits that requests
+	// hand over, so that no request waits for the database to record them
+	cache.StartPendingCountWrites()
+
+	// Create the fetcher config
+	fetcherCfg := httpfetcher.DefaultConfig()
+	fetcherCfg.AllowHTTP = s.config.AllowHTTP
+	fetcherCfg.Timeout = s.config.UpstreamFetchTimeout
+	fetcherCfg.MaxResponseSize = s.config.UpstreamMaxResponseSize
+
+	if s.config.UpstreamConnectionsPerHost > 0 {
+		fetcherCfg.MaxConnectionsPerHost = s.config.UpstreamConnectionsPerHost
+	}
+
+	fetcherCfg.MaxConnections = s.config.UpstreamConnections
+	fetcherCfg.BlockedNetworks = s.config.BlockedNetworks
+
+	// Create the service. With no fetcher provided, it builds its own from
+	// fetcherCfg.
+	svc, err := imgcache.NewService(&imgcache.ServiceConfig{
+		Cache:                   cache,
+		FetcherConfig:           fetcherCfg,
+		Fetcher:                 s.fetcher,
+		SigningKey:              s.config.SigningKey,
+		Allowlist:               s.config.AllowlistHosts,
+		MaxConcurrentProcessing: s.config.MaxConcurrentProcessing,
+		Logger:                  s.log,
+	})
+	if err != nil {
+		return err
+	}
+
+	s.imgSvc = svc
+	s.log.Info("image service initialized")
+
+	// Initialize session manager (signing key is validated at config load
+	// time). Session cookies are always Secure/HttpOnly/SameSite=Strict.
+	// The random value that each logout replaces is saved in the database,
+	// so it outlasts a restart.
+	sessMgr, err := session.NewManagerWithDatabase(
+		context.Background(), s.config.SigningKey, s.db.DB())
+	if err != nil {
+		return err
+	}
+
+	s.sessMgr = sessMgr
+
+	// Initialize encrypted URL generator
+	encGen, err := encurl.NewGenerator(s.config.SigningKey)
+	if err != nil {
+		return err
+	}
+
+	s.encGen = encGen
+
+	s.log.Info("session manager and URL generator initialized")
+
+	return nil
+}
+
 func (s *Handlers) respondJSON(w http.ResponseWriter, data any, status int) {
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(status)

internal/handlers/handlers_internal_test.go

@@ -18,20 +18,15 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/v5"
-	"github.com/prometheus/client_golang/prometheus"
-	"sneak.berlin/go/pixa/internal/allowlist"
 	"sneak.berlin/go/pixa/internal/database"
 	"sneak.berlin/go/pixa/internal/httpfetcher"
-	"sneak.berlin/go/pixa/internal/imageprocessor"
-	"sneak.berlin/go/pixa/internal/imageproxy"
-	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/imgcache"
-	"sneak.berlin/go/pixa/internal/signature"
 )
 
 // testFixtures contains test data.
 type testFixtures struct {
 	handler  *Handlers
+	service  *imgcache.Service
 	goodHost string
 }
 
@@ -50,37 +45,32 @@ func setupTestHandler(t *testing.T) *testFixtures {
 	tmpDir := t.TempDir()
 	db := setupTestDB(t)
 
-	cache, err := imgcache.NewCache(db, imgcache.Config{
+	cache, err := imgcache.NewCache(db, imgcache.CacheConfig{
 		StateDir:    tmpDir,
 		NegativeTTL: 5 * time.Minute,
-		MaxBytes:    1 << 30,
-	}, prometheus.NewRegistry())
+	})
 	if err != nil {
 		t.Fatalf("failed to create cache: %v", err)
 	}
 
-	svc, err := imageproxy.New(&imageproxy.Config{
-		Cache:   cache,
-		Fetcher: newMockFetcher(mockFS),
-		Processor: imageprocessor.New(imageprocessor.Params{
-			MaxInputBytes:           50 << 20,
-			MaxConcurrentProcessing: 2,
-		}),
-		MaxResponseSize: 50 << 20,
-	}, prometheus.NewRegistry())
+	svc, err := imgcache.NewService(&imgcache.ServiceConfig{
+		Cache:      cache,
+		Fetcher:    newMockFetcher(mockFS),
+		SigningKey: "test-signing-key-must-be-32-chars",
+		Allowlist:  []string{goodHost},
+	})
 	if err != nil {
-		t.Fatalf("failed to create proxy: %v", err)
+		t.Fatalf("failed to create service: %v", err)
 	}
 
 	h := &Handlers{
-		imgSvc:    svc,
-		log:       slog.Default(),
-		signer:    signature.New("test-signing-key-must-be-32-chars"),
-		allowlist: allowlist.New([]string{goodHost}),
+		imgSvc: svc,
+		log:    slog.Default(),
 	}
 
 	return &testFixtures{
 		handler:  h,
+		service:  svc,
 		goodHost: goodHost,
 	}
 }
@@ -131,9 +121,10 @@ func newMockFetcher(fs fs.FS) *mockFetcher {
 }
 
 func (f *mockFetcher) Fetch(
-	_ context.Context, source imagerequest.Source,
+	_ context.Context, url string,
 ) (*httpfetcher.FetchResult, error) {
-	path := source.Host + source.Path
+	// Remove https:// prefix
+	path := url[8:] // Remove "https://"
 
 	data, err := fs.ReadFile(f.fs, path)
 	if err != nil {

internal/handlers/image.go

@@ -1,31 +1,23 @@
 package handlers
 
 import (
-	"context"
 	"errors"
 	"fmt"
 	"io"
 	"net/http"
 	"net/url"
 	"strconv"
-	"strings"
 	"time"
 
 	"github.com/go-chi/chi/v5/middleware"
 	"sneak.berlin/go/pixa/internal/encurl"
 	"sneak.berlin/go/pixa/internal/httpfetcher"
 	"sneak.berlin/go/pixa/internal/imageprocessor"
-	"sneak.berlin/go/pixa/internal/imageproxy"
 	"sneak.berlin/go/pixa/internal/imagerequest"
+	"sneak.berlin/go/pixa/internal/imgcache"
 	"sneak.berlin/go/pixa/internal/magic"
 )
 
-// statusClientClosedRequest is the status nginx calls "client closed
-// request". The image routes answer it when the client goes away before its
-// image is ready, unless its request is the one making the image. Nobody reads
-// it; it is for logs and metrics.
-const statusClientClosedRequest = 499
-
 // HandleImage handles the main image proxy route:
 // /v1/image/<host>/<path>/<width>x<height>.<format>, or with no format
 // /v1/image/<host>/<path>/<width>x<height>
@@ -35,13 +27,13 @@ func (s *Handlers) HandleImage() http.HandlerFunc {
 			return
 		}
 
-		req, sig, expires, ok := s.parseImageRequest(w, r)
+		req, ok := s.parseImageRequest(w, r)
 		if !ok {
 			return
 		}
 
 		// Validate signature if required
-		err := s.validateSignature(req, sig, expires)
+		err := s.imgSvc.ValidateRequest(req)
 		if err != nil {
 			s.log.Warn("signature validation failed",
 				"host", req.Source.Host,
@@ -53,7 +45,27 @@ func (s *Handlers) HandleImage() http.HandlerFunc {
 			return
 		}
 
-		s.serveImage(w, r, req, expires)
+		// The signature covers the format auto, not the format chosen
+		if !s.chooseAutoFormat(w, r, req) {
+			return
+		}
+
+		// Get cache key for logging
+		cacheKey := imagerequest.CacheKey(req)
+
+		// Get the image (from cache or fetch/process)
+		startTime := time.Now()
+
+		resp, err := s.imgSvc.Get(r.Context(), req)
+		if err != nil {
+			s.respondImageError(w, req, err)
+
+			return
+		}
+
+		defer func() { _ = resp.Content.Close() }()
+
+		s.writeImageResponse(w, r, req, resp, cacheKey, startTime)
 	}
 }
 
@@ -70,11 +82,11 @@ func (s *Handlers) HandleRobotsTxt() http.HandlerFunc {
 }
 
 // parseImageRequest parses the image URL's path and query parameters into
-// an image request, and returns it with the URL's signature and expiry. On
-// invalid input it writes an error response and returns false.
+// an image request. On invalid input it writes an error response and
+// returns false.
 func (s *Handlers) parseImageRequest(
 	w http.ResponseWriter, r *http.Request,
-) (*imagerequest.Request, string, time.Time, bool) {
+) (*imagerequest.Request, bool) {
 	// The path is parsed decoded once, as r.URL.Path holds it, and not from
 	// chi's wildcard: chi routes on the path as the client wrote it whenever
 	// that is not Go's own encoding of it, so its wildcard would still hold
@@ -88,7 +100,7 @@ func (s *Handlers) parseImageRequest(
 		)
 		s.respondError(w, "invalid image URL: "+err.Error(), http.StatusBadRequest)
 
-		return nil, "", time.Time{}, false
+		return nil, false
 	}
 
 	// Parse signature params from query string. r.URL.Query() would silently
@@ -101,7 +113,7 @@ func (s *Handlers) parseImageRequest(
 		s.respondError(w, fmt.Sprintf("invalid query string %q: %v",
 			r.URL.RawQuery, err), http.StatusBadRequest)
 
-		return nil, "", time.Time{}, false
+		return nil, false
 	}
 
 	for name, values := range query {
@@ -109,15 +121,17 @@ func (s *Handlers) parseImageRequest(
 			s.respondError(w, fmt.Sprintf("invalid %s: given more than once",
 				name), http.StatusBadRequest)
 
-			return nil, "", time.Time{}, false
+			return nil, false
 		}
 	}
 
-	expires, err := parseExpires(query)
+	req.Signature = query.Get("sig")
+
+	req.Expires, err = parseExpires(query)
 	if err != nil {
 		s.respondError(w, err.Error(), http.StatusBadRequest)
 
-		return nil, "", time.Time{}, false
+		return nil, false
 	}
 
 	// Parse optional quality and fit params. Only a q missing from the URL is
@@ -129,7 +143,7 @@ func (s *Handlers) parseImageRequest(
 		s.respondError(w, `invalid q: not a number, got ""`,
 			http.StatusBadRequest)
 
-		return nil, "", time.Time{}, false
+		return nil, false
 	}
 
 	req.Transform.Quality, err = parseFormInt(query, "q",
@@ -138,7 +152,7 @@ func (s *Handlers) parseImageRequest(
 		s.respondError(w, fmt.Sprintf("%v, got %q", err, qStr),
 			http.StatusBadRequest)
 
-		return nil, "", time.Time{}, false
+		return nil, false
 	}
 
 	// Only a fit missing from the URL is cover. A fit in the URL that is not a
@@ -148,7 +162,7 @@ func (s *Handlers) parseImageRequest(
 	if query.Has("fit") && req.Transform.FitMode == "" {
 		s.respondError(w, `invalid fit: not a fit mode, got ""`, http.StatusBadRequest)
 
-		return nil, "", time.Time{}, false
+		return nil, false
 	}
 
 	// Default fit mode if not set
@@ -165,40 +179,15 @@ func (s *Handlers) parseImageRequest(
 		s.respondError(w, "invalid image request: "+err.Error(),
 			http.StatusBadRequest)
 
-		return nil, "", time.Time{}, false
+		return nil, false
 	}
 
-	return req, query.Get("sig"), expires, true
-}
-
-// validateSignature returns nil when the source host of req is on
-// allowlist_hosts and names no port. Otherwise it verifies sig, the URL's
-// signature of req, and expires, the URL's expiry.
-func (s *Handlers) validateSignature(
-	req *imagerequest.Request, sig string, expires time.Time,
-) error {
-	// An allowlist entry names no port, so a host followed by ":", with or
-	// without a port, needs a signature. Go's URL type reads the port as the
-	// fetcher does: in an IPv6 address written without brackets, such as
-	// 2001:db8::1:8443, it is what follows the last ":". This is checked here
-	// and not in allowlist.IsAllowed, which also matches referer_blocklist,
-	// where a Referer must be blocked whatever its port. Port and IsAllowed
-	// read only the host of a URL.
-	sourceURL := &url.URL{Host: req.Source.Host}
-	hostHasPort := sourceURL.Port() != "" ||
-		strings.HasSuffix(sourceURL.Host, ":")
-
-	if !hostHasPort && s.allowlist.IsAllowed(sourceURL) {
-		return nil
-	}
-
-	// Signature required for non-allowed hosts
-	return s.signer.Verify(req, sig, expires)
+	return req, true
 }
 
 // parseExpires reads the exp query parameter, a Unix time in seconds. An exp
-// missing from the URL gives the zero time, which the signature check refuses
-// as a missing exp. An exp in the URL that is not a whole number, an empty
+// missing from the URL gives the zero time, which the signature check takes
+// as no expiration. An exp in the URL that is not a whole number, an empty
 // one included, is an error naming exp and the value.
 func parseExpires(query url.Values) (time.Time, error) {
 	if !query.Has("exp") {
@@ -226,11 +215,7 @@ func (s *Handlers) HandleTooManyRequests() http.HandlerFunc {
 	}
 }
 
-// respondImageError answers err, the image service's error for req, on both
-// image routes. It logs a 500 at error level, as pixa's own failure. It logs
-// the other answers at warn level, since the client, the upstream or a full
-// limit caused them. The 415 for a source refused for its first bytes is not
-// logged here, because the image service logs it.
+// respondImageError maps image retrieval errors to HTTP responses.
 func (s *Handlers) respondImageError(
 	w http.ResponseWriter, req *imagerequest.Request, err error,
 ) {
@@ -246,53 +231,59 @@ func (s *Handlers) respondImageError(
 		return
 	}
 
-	var (
-		status  int
-		message string
-	)
-
-	switch {
-	case errors.Is(err, httpfetcher.ErrSSRFBlocked):
-		status, message = http.StatusForbidden, "forbidden"
-	case errors.Is(err, httpfetcher.ErrUpstreamError):
-		status, message = http.StatusBadGateway, "upstream error"
-	case errors.Is(err, httpfetcher.ErrUpstreamTimeout):
-		status, message = http.StatusGatewayTimeout, "upstream timeout"
-	case errors.Is(err, httpfetcher.ErrTooManyConnections),
-		errors.Is(err, imageprocessor.ErrTooManyImages),
-		errors.Is(err, imageproxy.ErrProcessingTimedOut):
-		status = http.StatusServiceUnavailable
-		message = "server busy, try again later"
-	case errors.Is(err, httpfetcher.ErrInvalidContentType),
-		errors.Is(err, imageprocessor.ErrUnsupportedInputFormat):
-		status = http.StatusUnsupportedMediaType
-		message = "unsupported source format"
-	case errors.Is(err, imageprocessor.ErrOutputTooLarge):
-		status = http.StatusBadRequest
-		message = fmt.Sprintf("size too large for the source: the side "+
-			"computed from its proportions is above %d",
-			imageprocessor.MaxOutputDimension)
-	case errors.Is(err, imageprocessor.ErrAVIFOutputTooLarge):
-		status = http.StatusBadRequest
-		message = fmt.Sprintf("size too large for AVIF: the output "+
-			"would be above %d pixels", imageprocessor.MaxAVIFOutputPixels)
-	default:
-		s.log.Error("failed to get image",
-			"host", req.Source.Host,
-			"path", req.Source.Path,
-			"error", err,
-		)
-		s.respondError(w, "internal error", http.StatusInternalServerError)
-
-		return
-	}
-
-	s.log.Warn("failed to get image",
+	s.log.Error("failed to get image",
 		"host", req.Source.Host,
 		"path", req.Source.Path,
 		"error", err,
 	)
-	s.respondError(w, message, status)
+
+	// Check for specific error types
+	if errors.Is(err, httpfetcher.ErrSSRFBlocked) {
+		s.respondError(w, "forbidden", http.StatusForbidden)
+
+		return
+	}
+
+	if errors.Is(err, httpfetcher.ErrUpstreamError) {
+		s.respondError(w, "upstream error", http.StatusBadGateway)
+
+		return
+	}
+
+	if errors.Is(err, httpfetcher.ErrTooManyConnections) ||
+		errors.Is(err, imageprocessor.ErrTooManyImages) ||
+		errors.Is(err, imgcache.ErrProcessingTimedOut) {
+		s.respondError(w, "server busy, try again later",
+			http.StatusServiceUnavailable)
+
+		return
+	}
+
+	if errors.Is(err, httpfetcher.ErrInvalidContentType) ||
+		errors.Is(err, imageprocessor.ErrUnsupportedInputFormat) {
+		s.respondError(w, "unsupported source format",
+			http.StatusUnsupportedMediaType)
+
+		return
+	}
+
+	if errors.Is(err, imageprocessor.ErrOutputTooLarge) {
+		s.respondError(w, fmt.Sprintf("size too large for the source: the side "+
+			"computed from its proportions is above %d",
+			imageprocessor.MaxOutputDimension), http.StatusBadRequest)
+
+		return
+	}
+
+	if errors.Is(err, imageprocessor.ErrAVIFOutputTooLarge) {
+		s.respondError(w, fmt.Sprintf("size too large for AVIF: the output "+
+			"would be above %d pixels", imageprocessor.MaxAVIFOutputPixels),
+			http.StatusBadRequest)
+
+		return
+	}
+
+	s.respondError(w, "internal error", http.StatusInternalServerError)
 }
 
 // cacheControl returns the Cache-Control header for an image served through a
@@ -349,50 +340,13 @@ func notModified(w http.ResponseWriter, r *http.Request, etag string) bool {
 	return true
 }
 
-// serveImage serves the image that req asks for. Both image routes call it
-// once they have the request and its URL's expiry, which ends the
-// Cache-Control max-age. It chooses the format for the format auto, answers
-// If-None-Match with 304 and HEAD with the headers only. It answers 499 when
-// the image service stopped because the client went away, and any other error
-// of the image service with respondImageError.
-func (s *Handlers) serveImage(
+// writeImageResponse writes headers and streams the image content,
+// handling conditional and HEAD requests.
+func (s *Handlers) writeImageResponse(
 	w http.ResponseWriter, r *http.Request,
-	req *imagerequest.Request, expires time.Time,
+	req *imagerequest.Request, resp *imgcache.ImageResponse,
+	cacheKey imagerequest.VariantKey, startTime time.Time,
 ) {
-	// The signature or the token covers the format auto, not the format chosen
-	format, ok := s.chooseAutoFormat(w, r, req.Transform.Format)
-	if !ok {
-		return
-	}
-
-	req.Transform.Format = format
-
-	startTime := time.Now()
-
-	resp, err := s.imgSvc.Get(r.Context(), req)
-
-	// The client went away before its image was ready, which is not pixa's
-	// failure. A cancellation while the request's context is live is pixa's,
-	// and respondImageError answers it 500.
-	if errors.Is(err, context.Canceled) && r.Context().Err() != nil {
-		s.log.Info("client went away before the image was ready",
-			"request_id", middleware.GetReqID(r.Context()),
-			"host", req.Source.Host,
-			"path", req.Source.Path,
-		)
-		w.WriteHeader(statusClientClosedRequest)
-
-		return
-	}
-
-	if err != nil {
-		s.respondImageError(w, req, err)
-
-		return
-	}
-
-	defer func() { _ = resp.Content.Close() }()
-
 	// Set response headers
 	w.Header().Set("Content-Type", resp.ContentType)
 
@@ -401,7 +355,7 @@ func (s *Handlers) serveImage(
 	}
 
 	// Cache control headers
-	w.Header().Set("Cache-Control", cacheControl(expires))
+	w.Header().Set("Cache-Control", cacheControl(req.Expires))
 	w.Header().Set("X-Pixa-Cache", string(resp.CacheStatus))
 
 	if notModified(w, r, resp.ETag) {
@@ -418,28 +372,18 @@ func (s *Handlers) serveImage(
 	// Stream the response
 	w.WriteHeader(http.StatusOK)
 
-	// A failed write is most often a client that has gone away, not pixa's
-	// failure, so it is logged at warn level
 	servedBytes, err := io.Copy(w, resp.Content)
 	if err != nil {
-		s.log.Warn("failed to write response",
-			"request_id", middleware.GetReqID(r.Context()),
-			"host", req.Source.Host,
-			"path", req.Source.Path,
-			"served_bytes", servedBytes,
+		s.log.Error("failed to write response",
 			"error", err,
 		)
-
-		return
 	}
 
 	// Log cache status and timing after serving
 	duration := time.Since(startTime)
 	s.log.Info("image served",
 		"request_id", middleware.GetReqID(r.Context()),
-		"cache_key", imagerequest.CacheKey(req),
-		"host", req.Source.Host,
-		"path", req.Source.Path,
+		"cache_key", cacheKey,
 		"cache_status", resp.CacheStatus,
 		"duration_ms", duration.Milliseconds(),
 		"format", req.Transform.Format,

internal/handlers/image_cache_control_internal_test.go

@@ -12,16 +12,10 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/v5"
-	"github.com/prometheus/client_golang/prometheus"
 
-	"sneak.berlin/go/pixa/internal/allowlist"
 	"sneak.berlin/go/pixa/internal/encurl"
-	"sneak.berlin/go/pixa/internal/imageprocessor"
-	"sneak.berlin/go/pixa/internal/imageproxy"
 	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/imgcache"
-	"sneak.berlin/go/pixa/internal/seal"
-	"sneak.berlin/go/pixa/internal/signature"
 )
 
 // photoPath is the path of the JPEG that newSignedHostServer serves.
@@ -36,46 +30,37 @@ func newSignedHostServer(
 ) (*Handlers, http.Handler) {
 	t.Helper()
 
-	cache, err := imgcache.NewCache(setupTestDB(t), imgcache.Config{
+	cache, err := imgcache.NewCache(setupTestDB(t), imgcache.CacheConfig{
 		StateDir:    t.TempDir(),
 		NegativeTTL: 5 * time.Minute,
-		MaxBytes:    1 << 30,
-	}, prometheus.NewRegistry())
+	})
 	if err != nil {
 		t.Fatalf("imgcache.NewCache() error = %v", err)
 	}
 
 	jpegData := generateTestJPEG(t, 100, 100, color.RGBA{255, 0, 0, 255})
 
-	svc, err := imageproxy.New(&imageproxy.Config{
+	svc, err := imgcache.NewService(&imgcache.ServiceConfig{
 		Cache: cache,
 		Fetcher: newMockFetcher(fstest.MapFS{
 			signedHost + photoPath: &fstest.MapFile{Data: jpegData},
 		}),
-		Processor: imageprocessor.New(imageprocessor.Params{
-			MaxInputBytes:           50 << 20,
-			MaxConcurrentProcessing: 2,
-		}),
-		MaxResponseSize: 50 << 20,
-		Logger:          log,
-	}, prometheus.NewRegistry())
+		SigningKey: testSigningKey,
+		Logger:     log,
+	})
 	if err != nil {
-		t.Fatalf("imageproxy.New() error = %v", err)
+		t.Fatalf("imgcache.NewService() error = %v", err)
 	}
 
-	keys, err := seal.DeriveKeys(testSigningKey)
+	encGen, err := encurl.NewGenerator(testSigningKey)
 	if err != nil {
-		t.Fatalf("seal.DeriveKeys() error = %v", err)
+		t.Fatalf("encurl.NewGenerator() error = %v", err)
 	}
 
-	encGen := encurl.NewGenerator(keys.EncryptedURLKey)
-
 	h := &Handlers{
-		log:       log,
-		imgSvc:    svc,
-		encGen:    encGen,
-		signer:    signature.New(testSigningKey),
-		allowlist: allowlist.New(nil),
+		log:    log,
+		imgSvc: svc,
+		encGen: encGen,
 	}
 
 	r := chi.NewRouter()
@@ -121,9 +106,9 @@ func getMaxAge(t *testing.T, srv http.Handler, target string) int {
 func TestHandleImage_SignedURL_MaxAgeEndsAtExp(t *testing.T) {
 	t.Parallel()
 
-	_, srv := newSignedHostServer(t, slog.New(slog.DiscardHandler))
+	h, srv := newSignedHostServer(t, slog.New(slog.DiscardHandler))
 
-	signedURL := generateSignedURL(testSigningKey, &imagerequest.Request{
+	signedURL, err := h.imgSvc.GenerateSignedURL("", &imagerequest.Request{
 		Source: imagerequest.Source{
 			Host: signedHost,
 			Path: photoPath,
@@ -133,6 +118,9 @@ func TestHandleImage_SignedURL_MaxAgeEndsAtExp(t *testing.T) {
 			Format: imagerequest.FormatJPEG,
 		},
 	}, time.Minute)
+	if err != nil {
+		t.Fatalf("GenerateSignedURL() error = %v", err)
+	}
 
 	maxAge := getMaxAge(t, srv, signedURL)
 	if maxAge < 50 || maxAge > 60 {
@@ -209,7 +197,8 @@ func TestHandleImageEnc_MaxAge(t *testing.T) {
 					Size:   imagerequest.Size{Width: 50, Height: 50},
 					Format: imagerequest.FormatJPEG,
 				},
-			}, tt.expires)
+				Expires: tt.expires,
+			})
 			if err != nil {
 				t.Fatalf("Generate() error = %v", err)
 			}

internal/handlers/image_errors_internal_test.go

@@ -1,28 +1,19 @@
 package handlers
 
 import (
-	"bytes"
-	"context"
 	"encoding/json"
 	"fmt"
 	"image/color"
-	"io"
 	"log/slog"
 	"net/http"
 	"net/http/httptest"
-	"slices"
 	"strings"
 	"testing"
 	"testing/fstest"
 	"time"
 
 	"github.com/go-chi/chi/v5"
-	"github.com/go-chi/chi/v5/middleware"
-	"github.com/prometheus/client_golang/prometheus"
-	"sneak.berlin/go/pixa/internal/allowlist"
 	"sneak.berlin/go/pixa/internal/httpfetcher"
-	"sneak.berlin/go/pixa/internal/imageprocessor"
-	"sneak.berlin/go/pixa/internal/imageproxy"
 	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/imgcache"
 	"sneak.berlin/go/pixa/internal/signature"
@@ -33,38 +24,29 @@ import (
 const allowlistedHost = "allowed.example.com"
 
 // newImageRoute returns the image route of a Handlers whose service fetches
-// with fetcher, and which checks signatures with testSigningKey.
+// with fetcher and checks signatures with testSigningKey.
 func newImageRoute(t *testing.T, fetcher httpfetcher.Fetcher) http.Handler {
 	t.Helper()
 
-	cache, err := imgcache.NewCache(setupTestDB(t), imgcache.Config{
+	cache, err := imgcache.NewCache(setupTestDB(t), imgcache.CacheConfig{
 		StateDir:    t.TempDir(),
 		NegativeTTL: 5 * time.Minute,
-		MaxBytes:    1 << 30,
-	}, prometheus.NewRegistry())
+	})
 	if err != nil {
 		t.Fatalf("failed to create cache: %v", err)
 	}
 
-	svc, err := imageproxy.New(&imageproxy.Config{
-		Cache:   cache,
-		Fetcher: fetcher,
-		Processor: imageprocessor.New(imageprocessor.Params{
-			MaxInputBytes:           50 << 20,
-			MaxConcurrentProcessing: 2,
-		}),
-		MaxResponseSize: 50 << 20,
-	}, prometheus.NewRegistry())
+	svc, err := imgcache.NewService(&imgcache.ServiceConfig{
+		Cache:      cache,
+		Fetcher:    fetcher,
+		SigningKey: testSigningKey,
+		Allowlist:  []string{allowlistedHost},
+	})
 	if err != nil {
-		t.Fatalf("failed to create proxy: %v", err)
+		t.Fatalf("failed to create service: %v", err)
 	}
 
-	h := &Handlers{
-		imgSvc:    svc,
-		log:       slog.New(slog.DiscardHandler),
-		signer:    signature.New(testSigningKey),
-		allowlist: allowlist.New([]string{allowlistedHost}),
-	}
+	h := &Handlers{imgSvc: svc, log: slog.New(slog.DiscardHandler)}
 
 	r := chi.NewRouter()
 	r.Get("/v1/image/*", h.HandleImage())
@@ -73,7 +55,7 @@ func newImageRoute(t *testing.T, fetcher httpfetcher.Fetcher) http.Handler {
 }
 
 // newPhotoFetcher returns a mock fetcher that serves a JPEG at photoPath on
-// each of hosts, and answers any other source with an upstream error.
+// each of hosts, and answers any other URL with an upstream error.
 func newPhotoFetcher(t *testing.T, hosts ...string) *httpfetcher.MockFetcher {
 	t.Helper()
 
@@ -100,10 +82,10 @@ func photoURLWithSig(host, sig string, expires time.Time) string {
 	return fmt.Sprintf("%s?sig=%s&exp=%d", photoURL(host), sig, expires.Unix())
 }
 
-// photoRequest returns the image request of photoURL(host) at the default
-// quality and fit.
-func photoRequest(host string) *imagerequest.Request {
-	return &imagerequest.Request{
+// photoSignature returns the signature of photoURL(host) at the default
+// quality and fit, made with key and expiring at expires.
+func photoSignature(key, host string, expires time.Time) string {
+	return signature.New(key).Sign(&imagerequest.Request{
 		Source: imagerequest.Source{
 			Host: host,
 			Path: photoPath,
@@ -114,13 +96,8 @@ func photoRequest(host string) *imagerequest.Request {
 			Quality: 85,
 			FitMode: imagerequest.FitCover,
 		},
-	}
-}
-
-// photoSignature returns the signature of photoURL(host) at the default
-// quality and fit, made with key and expiring at expires.
-func photoSignature(key, host string, expires time.Time) string {
-	return signature.New(key).Sign(photoRequest(host), expires)
+		Expires: expires,
+	})
 }
 
 // sendGet sends a GET for target to route and returns the response.
@@ -191,12 +168,7 @@ func TestHandleImage_ErrorAnswers(t *testing.T) {
 	photos := newPhotoFetcher(t,
 		signedHost, parentHost, siblingHost, subdomainHost, appendedHost)
 	// The real fetcher refuses localhost before any lookup or connection.
-	realFetcher := httpfetcher.New(&httpfetcher.Config{
-		Timeout:               30 * time.Second,
-		MaxResponseSize:       50 << 20,
-		MaxConnectionsPerHost: 20,
-		MaxConnections:        64,
-	})
+	realFetcher := httpfetcher.New(httpfetcher.DefaultConfig())
 
 	exp := time.Now().Add(time.Hour)
 	expired := time.Now().Add(-time.Hour)
@@ -301,9 +273,10 @@ func TestHandleImage_AllowlistOrSignature(t *testing.T) {
 // host can be, and checks that each is refused with 400 naming the host as
 // decoded: allowlistedHost with a character after it that a URL host cannot
 // hold, percent-encoded, an IPv6 address without brackets, and brackets
-// around something that is not an IPv6 address. Later steps put the host
-// unparsed into the allowlist check, the cache key and the upstream URL, so
-// such a host is refused first.
+// around something that is not an IPv6 address. A "?" or "#" after
+// allowlistedHost would otherwise end the host when the source URL is read,
+// so the request would pass the allowlist and be fetched and cached under a
+// host that is not the one fetched.
 func TestHandleImage_InvalidHost_Returns400(t *testing.T) {
 	t.Parallel()
 
@@ -374,9 +347,10 @@ func TestHandleImage_HostForms_Served(t *testing.T) {
 
 // TestHandleImage_HashInSourcePathOrQuery_Returns400 sends image URLs whose
 // source path or source query holds a "#", written as %23, and checks that
-// each is refused with 400, the one signed for that source path included.
-// A "#" starts a URL's fragment, so neither the source path nor the source
-// query may hold one.
+// each is refused with 400, the one signed for that source path included. The
+// source URL would otherwise end at the "#" when it is fetched, so each text
+// after it would fetch the image at photoPath and cache it under keys of its
+// own.
 func TestHandleImage_HashInSourcePathOrQuery_Returns400(t *testing.T) {
 	t.Parallel()
 
@@ -394,7 +368,8 @@ func TestHandleImage_HashInSourcePathOrQuery_Returns400(t *testing.T) {
 			Quality: 85,
 			FitMode: imagerequest.FitCover,
 		},
-	}, exp)
+		Expires: exp,
+	})
 
 	tests := []struct {
 		name   string
@@ -420,168 +395,3 @@ func TestHandleImage_HashInSourcePathOrQuery_Returns400(t *testing.T) {
 		})
 	}
 }
-
-// failingFetcher answers every fetch with its error.
-type failingFetcher struct {
-	err error
-}
-
-// Fetch returns f's error.
-func (f failingFetcher) Fetch(
-	context.Context, imagerequest.Source,
-) (*httpfetcher.FetchResult, error) {
-	return nil, f.err
-}
-
-// photoURLsByRoute returns, for each image route, the function that makes the
-// URL of the JPEG at photoPath on signedHost on that route.
-func photoURLsByRoute() map[string]func(*testing.T, *Handlers) string {
-	return map[string]func(*testing.T, *Handlers) string{
-		"/v1/image/": signedPhotoURL,
-		"/v1/e/":     encPhotoURL,
-	}
-}
-
-// TestImageRoutes_SameErrorAnswers checks that both image routes answer each
-// upstream fetch error below with the same status. They log it as "failed to
-// get image" at the same level: error for the 500 and warn for the others.
-// Each request gets routes of its own, so no request finds another's failed
-// fetch in the negative cache.
-func TestImageRoutes_SameErrorAnswers(t *testing.T) {
-	t.Parallel()
-
-	tests := []struct {
-		name       string
-		err        error
-		wantStatus int
-		wantLevel  slog.Level
-	}{
-		{"blocked upstream address", httpfetcher.ErrSSRFBlocked,
-			http.StatusForbidden, slog.LevelWarn},
-		{"upstream error status",
-			fmt.Errorf("%w: status 404", httpfetcher.ErrUpstreamError),
-			http.StatusBadGateway, slog.LevelWarn},
-		{"no response headers within the fetch timeout",
-			httpfetcher.ErrUpstreamTimeout, http.StatusGatewayTimeout,
-			slog.LevelWarn},
-		{"no free upstream connection", httpfetcher.ErrTooManyConnections,
-			http.StatusServiceUnavailable, slog.LevelWarn},
-		{"Content-Type not a source format",
-			fmt.Errorf("%w: image/svg+xml", httpfetcher.ErrInvalidContentType),
-			http.StatusUnsupportedMediaType, slog.LevelWarn},
-		{"any other failure", io.ErrUnexpectedEOF,
-			http.StatusInternalServerError, slog.LevelError},
-	}
-
-	for _, tt := range tests {
-		for route, imageURL := range photoURLsByRoute() {
-			t.Run(route+" "+tt.name, func(t *testing.T) {
-				t.Parallel()
-
-				var logs bytes.Buffer
-
-				h, routes := newRoutesFetchingThrough(t,
-					failingFetcher{err: tt.err},
-					slog.New(slog.NewJSONHandler(&logs, nil)))
-
-				rec := sendGet(t, routes, imageURL(t, h))
-				if rec.Code != tt.wantStatus {
-					t.Errorf("status = %d, want %d: %s",
-						rec.Code, tt.wantStatus, rec.Body)
-				}
-
-				levels := loggedLevels(t, &logs)
-				if !slices.Contains(levels[tt.wantLevel.String()],
-					"failed to get image") {
-					t.Errorf(`no "failed to get image" line logged at level %s`,
-						tt.wantLevel)
-				}
-
-				if tt.wantLevel != slog.LevelError &&
-					len(levels[slog.LevelError.String()]) != 0 {
-					t.Errorf("logged at error level: %q",
-						levels[slog.LevelError.String()])
-				}
-			})
-		}
-	}
-}
-
-// failingResponseWriter is a response writer whose Write always fails, as when
-// the client has gone away.
-type failingResponseWriter struct {
-	*httptest.ResponseRecorder
-}
-
-// Write writes nothing and returns io.ErrClosedPipe.
-func (failingResponseWriter) Write([]byte) (int, error) {
-	return 0, io.ErrClosedPipe
-}
-
-// TestImageRoutes_FailedWriteLoggedOnce checks that both image routes log a
-// failed write of the image once, at warn level, with the request's ID, the
-// source host and path, the bytes served and the error. Neither may also log
-// the image as served.
-func TestImageRoutes_FailedWriteLoggedOnce(t *testing.T) {
-	t.Parallel()
-
-	const requestID = "test-request-id"
-
-	for route, imageURL := range photoURLsByRoute() {
-		t.Run(route, func(t *testing.T) {
-			t.Parallel()
-
-			var logs bytes.Buffer
-
-			h, srv := newSignedHostServer(t,
-				slog.New(slog.NewJSONHandler(&logs, nil)))
-
-			ctx := context.WithValue(t.Context(),
-				middleware.RequestIDKey, requestID)
-			srv.ServeHTTP(failingResponseWriter{httptest.NewRecorder()},
-				httptest.NewRequestWithContext(
-					ctx, http.MethodGet, imageURL(t, h), nil))
-
-			t.Logf("logged:\n%s", logs.String())
-
-			var failedWrites []map[string]any
-
-			dec := json.NewDecoder(&logs)
-			for dec.More() {
-				var line map[string]any
-
-				err := dec.Decode(&line)
-				if err != nil {
-					t.Fatalf("decoding log line: %v", err)
-				}
-
-				switch line["msg"] {
-				case "image served":
-					t.Error(`"image served" logged after a failed write`)
-				case "failed to write response":
-					failedWrites = append(failedWrites, line)
-				}
-			}
-
-			if len(failedWrites) != 1 {
-				t.Fatalf(`"failed to write response" logged %d times, want 1`,
-					len(failedWrites))
-			}
-
-			want := map[string]any{
-				"level":        slog.LevelWarn.String(),
-				"request_id":   requestID,
-				"host":         signedHost,
-				"path":         photoPath,
-				"served_bytes": float64(0),
-				"error":        io.ErrClosedPipe.Error(),
-			}
-
-			for key, wantValue := range want {
-				if got := failedWrites[0][key]; got != wantValue {
-					t.Errorf("%s = %v, want %v", key, got, wantValue)
-				}
-			}
-		})
-	}
-}

internal/handlers/image_signature_internal_test.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"net/http"
 	"net/http/httptest"
-	"net/url"
 	"testing"
 	"time"
 
@@ -37,47 +36,6 @@ func getImage(t *testing.T, fix *testFixtures, target string) int {
 	return rec.Code
 }
 
-// generateSignedURL returns the /v1/image/ URL of req, signed with key and
-// expiring after ttl. It signs a copy of req, so req itself is not changed.
-// An unset quality or fit in the copy is set to 85 or cover, the values the
-// route uses when a URL has no q or fit. The URL carries q and fit next to sig
-// and exp, so the route verifies it for the quality and fit it was signed
-// with.
-func generateSignedURL(
-	key string, req *imagerequest.Request, ttl time.Duration,
-) string {
-	signed := *req
-
-	if signed.Transform.Quality == 0 {
-		signed.Transform.Quality = 85
-	}
-
-	if signed.Transform.FitMode == "" {
-		signed.Transform.FitMode = imagerequest.FitCover
-	}
-
-	expires := time.Now().Add(ttl)
-	sig := signature.New(key).Sign(&signed, expires)
-
-	// A source query follows the source path after a "?". The image route
-	// reads the path decoded once, so the whole path is written in Go's own
-	// percent-encoding of a URL path, which writes "?" as %3F and "%" as %25,
-	// and leaves "/", ";", ",", "=" and "&" as they are.
-	sourcePathAndQuery := signed.Source.Path
-	if signed.Source.Query != "" {
-		sourcePathAndQuery += "?" + signed.Source.Query
-	}
-
-	unescapedPath := fmt.Sprintf("/v1/image/%s%s/%dx%d.%s",
-		signed.Source.Host, sourcePathAndQuery,
-		signed.Transform.Size.Width, signed.Transform.Size.Height,
-		signed.Transform.Format)
-
-	return fmt.Sprintf("%s?sig=%s&exp=%d&q=%d&fit=%s",
-		(&url.URL{Path: unescapedPath}).EscapedPath(), sig, expires.Unix(),
-		signed.Transform.Quality, signed.Transform.FitMode)
-}
-
 // TestHandleImage_SignatureCoversQualityAndFit signs a URL for quality 85
 // and fit cover, the values the route uses when a URL has no q or fit, and
 // sends that signature with each q and fit below.
@@ -97,7 +55,8 @@ func TestHandleImage_SignatureCoversQualityAndFit(t *testing.T) {
 			Quality: 85,
 			FitMode: imagerequest.FitCover,
 		},
-	}, expires)
+		Expires: expires,
+	})
 	signedURL := fmt.Sprintf("/v1/image/%s/images/photo.jpg/50x50.jpeg?sig=%s&exp=%d",
 		signedHost, sig, expires.Unix())
 
@@ -124,8 +83,8 @@ func TestHandleImage_SignatureCoversQualityAndFit(t *testing.T) {
 	}
 }
 
-// TestHandleImage_GeneratedSignedURLVerifies sends URLs built by
-// generateSignedURL to the route.
+// TestHandleImage_GeneratedSignedURLVerifies sends URLs built by the
+// service's signed-URL generator to the route.
 func TestHandleImage_GeneratedSignedURLVerifies(t *testing.T) {
 	t.Parallel()
 
@@ -142,21 +101,25 @@ func TestHandleImage_GeneratedSignedURLVerifies(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			signedURL := generateSignedURL("test-signing-key-must-be-32-chars",
-				&imagerequest.Request{
-					Source: imagerequest.Source{
-						Host: signedHost,
-						Path: "/images/photo.jpg",
-					},
-					Transform: imagerequest.Transform{
-						Size:    imagerequest.Size{Width: 50, Height: 50},
-						Format:  imagerequest.FormatJPEG,
-						Quality: tt.quality,
-						FitMode: tt.fitMode,
-					},
-				}, time.Hour)
+			fix := setupTestHandler(t)
 
-			status := getImage(t, setupTestHandler(t), signedURL)
+			signedURL, err := fix.service.GenerateSignedURL("", &imagerequest.Request{
+				Source: imagerequest.Source{
+					Host: signedHost,
+					Path: "/images/photo.jpg",
+				},
+				Transform: imagerequest.Transform{
+					Size:    imagerequest.Size{Width: 50, Height: 50},
+					Format:  imagerequest.FormatJPEG,
+					Quality: tt.quality,
+					FitMode: tt.fitMode,
+				},
+			}, time.Hour)
+			if err != nil {
+				t.Fatalf("GenerateSignedURL() error = %v", err)
+			}
+
+			status := getImage(t, fix, signedURL)
 			if status != http.StatusBadGateway {
 				t.Errorf("status = %d, want %d", status, http.StatusBadGateway)
 			}
@@ -215,10 +178,10 @@ func TestHandleImage_InvalidExp_Returns400(t *testing.T) {
 }
 
 // TestHandleImage_GeneratedSignedURLWithSourceQueryVerifies sends URLs built
-// by generateSignedURL for source URLs with a query to the route, through a
-// chi router: chi routes on the path as the client wrote it whenever that is
-// not Go's own encoding of it. A 502 means the signature passed, so the route
-// read the source path and query that were signed.
+// by the service's signed-URL generator for source URLs with a query to the
+// route, through a chi router: chi routes on the path as the client wrote it
+// whenever that is not Go's own encoding of it. A 502 means the signature
+// passed, so the route read the source path and query that were signed.
 func TestHandleImage_GeneratedSignedURLWithSourceQueryVerifies(t *testing.T) {
 	t.Parallel()
 
@@ -238,20 +201,24 @@ func TestHandleImage_GeneratedSignedURLWithSourceQueryVerifies(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			signedURL := generateSignedURL("test-signing-key-must-be-32-chars",
-				&imagerequest.Request{
-					Source: imagerequest.Source{
-						Host:  signedHost,
-						Path:  photoPath,
-						Query: tt.query,
-					},
-					Transform: imagerequest.Transform{
-						Size:   imagerequest.Size{Width: 50, Height: 50},
-						Format: imagerequest.FormatJPEG,
-					},
-				}, time.Hour)
+			fix := setupTestHandler(t)
 
-			status := getImage(t, setupTestHandler(t), signedURL)
+			signedURL, err := fix.service.GenerateSignedURL("", &imagerequest.Request{
+				Source: imagerequest.Source{
+					Host:  signedHost,
+					Path:  photoPath,
+					Query: tt.query,
+				},
+				Transform: imagerequest.Transform{
+					Size:   imagerequest.Size{Width: 50, Height: 50},
+					Format: imagerequest.FormatJPEG,
+				},
+			}, time.Hour)
+			if err != nil {
+				t.Fatalf("GenerateSignedURL() error = %v", err)
+			}
+
+			status := getImage(t, fix, signedURL)
 			if status != http.StatusBadGateway {
 				t.Errorf("status = %d, want %d", status, http.StatusBadGateway)
 			}
@@ -280,7 +247,8 @@ func TestHandleImage_SourceQueryEncodedAnyWay(t *testing.T) {
 			Quality: 85,
 			FitMode: imagerequest.FitCover,
 		},
-	}, expires)
+		Expires: expires,
+	})
 
 	tests := []struct {
 		name         string
@@ -312,7 +280,7 @@ func TestHandleImage_SourceQueryEncodedAnyWay(t *testing.T) {
 // TestHandleImage_SourceURLHoldingPercent25Verifies signs a source path and a
 // source query that each hold %25, the percent-escape of a literal "%", and
 // sends each to the route written as the README says, with that "%" written as
-// %25, and as generateSignedURL writes it. A 502 means the signature passed.
+// %25, and as GenerateSignedURL writes it. A 502 means the signature passed.
 func TestHandleImage_SourceURLHoldingPercent25Verifies(t *testing.T) {
 	t.Parallel()
 
@@ -346,7 +314,8 @@ func TestHandleImage_SourceURLHoldingPercent25Verifies(t *testing.T) {
 					Quality: 85,
 					FitMode: imagerequest.FitCover,
 				},
-			}, expires)
+				Expires: expires,
+			})
 
 			target := fmt.Sprintf("/v1/image/%s%s/50x50.jpeg?sig=%s&exp=%d",
 				signedHost, tt.writtenPathAndQuery, sig, expires.Unix())
@@ -357,23 +326,27 @@ func TestHandleImage_SourceURLHoldingPercent25Verifies(t *testing.T) {
 			}
 		})
 
-		t.Run(tt.name+" written by generateSignedURL", func(t *testing.T) {
+		t.Run(tt.name+" written by GenerateSignedURL", func(t *testing.T) {
 			t.Parallel()
 
-			signedURL := generateSignedURL("test-signing-key-must-be-32-chars",
-				&imagerequest.Request{
-					Source: imagerequest.Source{
-						Host:  signedHost,
-						Path:  tt.sourcePath,
-						Query: tt.sourceQuery,
-					},
-					Transform: imagerequest.Transform{
-						Size:   imagerequest.Size{Width: 50, Height: 50},
-						Format: imagerequest.FormatJPEG,
-					},
-				}, time.Hour)
+			fix := setupTestHandler(t)
 
-			status := getImage(t, setupTestHandler(t), signedURL)
+			signedURL, err := fix.service.GenerateSignedURL("", &imagerequest.Request{
+				Source: imagerequest.Source{
+					Host:  signedHost,
+					Path:  tt.sourcePath,
+					Query: tt.sourceQuery,
+				},
+				Transform: imagerequest.Transform{
+					Size:   imagerequest.Size{Width: 50, Height: 50},
+					Format: imagerequest.FormatJPEG,
+				},
+			}, time.Hour)
+			if err != nil {
+				t.Fatalf("GenerateSignedURL() error = %v", err)
+			}
+
+			status := getImage(t, fix, signedURL)
 			if status != http.StatusBadGateway {
 				t.Errorf("status = %d, want %d", status, http.StatusBadGateway)
 			}

internal/handlers/imageenc.go

@@ -2,13 +2,21 @@ package handlers
 
 import (
 	"errors"
+	"fmt"
+	"io"
 	"net/http"
+	"strconv"
 	"time"
 
 	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
 
 	"sneak.berlin/go/pixa/internal/encurl"
+	"sneak.berlin/go/pixa/internal/httpfetcher"
+	"sneak.berlin/go/pixa/internal/imageprocessor"
 	"sneak.berlin/go/pixa/internal/imagerequest"
+	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/magic"
 )
 
 // HandleImageEnc handles requests to /v1/e/{token}/* for encrypted
@@ -20,59 +28,157 @@ func (s *Handlers) HandleImageEnc() http.HandlerFunc {
 			return
 		}
 
-		req, expires, ok := s.parseImageEncRequest(w, r)
-		if !ok {
+		ctx := r.Context()
+		start := time.Now()
+
+		req, ok := s.parseImageEncRequest(w, r)
+		if !ok || !s.chooseAutoFormat(w, r, req) {
 			return
 		}
 
-		s.serveImage(w, r, req, expires)
+		// Log the request
+		s.log.Debug("encrypted image request",
+			"host", req.Source.Host,
+			"path", req.Source.Path,
+			"dimensions", fmt.Sprintf("%dx%d",
+				req.Transform.Size.Width, req.Transform.Size.Height),
+			"format", req.Transform.Format,
+		)
+
+		// Fetch and process the image (no signature validation
+		// needed - encrypted URL is trusted)
+		resp, err := s.imgSvc.Get(ctx, req)
+		if err != nil {
+			s.handleImageError(w, err)
+
+			return
+		}
+
+		defer func() { _ = resp.Content.Close() }()
+
+		// Set response headers
+		w.Header().Set("Content-Type", resp.ContentType)
+
+		if resp.ContentLength > 0 {
+			w.Header().Set("Content-Length", strconv.FormatInt(resp.ContentLength, 10))
+		}
+
+		// Cache headers: max-age ends at the URL's expiry
+		w.Header().Set("Cache-Control", cacheControl(req.Expires))
+		w.Header().Set("X-Pixa-Cache", string(resp.CacheStatus))
+
+		if notModified(w, r, resp.ETag) {
+			return
+		}
+
+		// A HEAD request gets the headers only
+		if r.Method == http.MethodHead {
+			w.WriteHeader(http.StatusOK)
+
+			return
+		}
+
+		// Stream the response
+		written, err := io.Copy(w, resp.Content)
+		if err != nil {
+			s.log.Error("failed to write response", "error", err)
+
+			return
+		}
+
+		// Log completion
+		duration := time.Since(start)
+		s.log.Info("image served",
+			"request_id", middleware.GetReqID(ctx),
+			"cache_key", imagerequest.CacheKey(req),
+			"host", req.Source.Host,
+			"path", req.Source.Path,
+			"format", req.Transform.Format,
+			"cache_status", resp.CacheStatus,
+			"served_bytes", written,
+			"duration_ms", duration.Milliseconds(),
+		)
 	}
 }
 
 // parseImageEncRequest decrypts the token of an encrypted image URL into an
-// image request and checks it, and returns it with the token's expiry. On a
-// token that is missing, does not decrypt, has expired or asks for something
-// not valid, it writes an error response and returns false.
+// image request and checks it. On a token that is missing, does not decrypt,
+// has expired or asks for something not valid, it writes an error response
+// and returns false.
 func (s *Handlers) parseImageEncRequest(
 	w http.ResponseWriter, r *http.Request,
-) (*imagerequest.Request, time.Time, bool) {
+) (*imagerequest.Request, bool) {
 	// Extract token from URL
 	token := chi.URLParam(r, "token")
 	if token == "" {
 		s.respondError(w, "missing token", http.StatusBadRequest)
 
-		return nil, time.Time{}, false
+		return nil, false
 	}
 
 	// Decrypt and validate the payload
-	req, expires, err := s.encGen.Parse(token)
+	req, err := s.encGen.Parse(token)
 	if err != nil {
 		if errors.Is(err, encurl.ErrExpired) {
 			s.log.Debug("encrypted URL expired", "error", err)
 			s.respondError(w, "URL has expired", http.StatusGone)
 
-			return nil, time.Time{}, false
+			return nil, false
 		}
 
-		s.log.Debug("invalid encrypted URL", "error", err)
+		s.log.Debug("failed to decrypt URL", "error", err)
 		s.respondError(w, "invalid encrypted URL", http.StatusBadRequest)
 
-		return nil, time.Time{}, false
+		return nil, false
 	}
 
 	// Apply the same dimension and fit-mode bounds as the plain image
 	// route: a sealed payload is trusted for its origin, not for staying
-	// within limits. This refuses an over-limit size before the source is
-	// fetched. An unknown fit mode is a 400 here rather than a 500 from the
-	// processor.
+	// within limits, so an over-limit size or unknown fit mode is a 400
+	// here rather than an out-of-memory or a 500 from the processor.
 	err = imagerequest.ValidateImageRequest(req)
 	if err != nil {
 		s.log.Debug("encrypted URL failed validation", "error", err)
 		s.respondError(w, "invalid encrypted URL: "+err.Error(),
 			http.StatusBadRequest)
 
-		return nil, time.Time{}, false
+		return nil, false
 	}
 
-	return req, expires, true
+	return req, true
+}
+
+// handleImageError converts image service errors to HTTP responses.
+func (s *Handlers) handleImageError(w http.ResponseWriter, err error) {
+	switch {
+	case errors.Is(err, httpfetcher.ErrSSRFBlocked):
+		s.respondError(w, "forbidden", http.StatusForbidden)
+	case errors.Is(err, httpfetcher.ErrUpstreamError):
+		s.respondError(w, "upstream error", http.StatusBadGateway)
+	case errors.Is(err, httpfetcher.ErrUpstreamTimeout):
+		s.respondError(w, "upstream timeout", http.StatusGatewayTimeout)
+	case errors.Is(err, httpfetcher.ErrTooManyConnections),
+		errors.Is(err, imageprocessor.ErrTooManyImages),
+		errors.Is(err, imgcache.ErrProcessingTimedOut):
+		s.respondError(w, "server busy, try again later",
+			http.StatusServiceUnavailable)
+	case errors.Is(err, httpfetcher.ErrInvalidContentType),
+		errors.Is(err, imageprocessor.ErrUnsupportedInputFormat),
+		errors.Is(err, magic.ErrMagicByteMismatch),
+		errors.Is(err, magic.ErrUnknownFormat),
+		errors.Is(err, magic.ErrNotEnoughData):
+		s.respondError(w, "unsupported source format",
+			http.StatusUnsupportedMediaType)
+	case errors.Is(err, imageprocessor.ErrOutputTooLarge):
+		s.respondError(w, fmt.Sprintf("size too large for the source: the side "+
+			"computed from its proportions is above %d",
+			imageprocessor.MaxOutputDimension), http.StatusBadRequest)
+	case errors.Is(err, imageprocessor.ErrAVIFOutputTooLarge):
+		s.respondError(w, fmt.Sprintf("size too large for AVIF: the output "+
+			"would be above %d pixels", imageprocessor.MaxAVIFOutputPixels),
+			http.StatusBadRequest)
+	default:
+		s.log.Error("image request failed", "error", err)
+		s.respondError(w, "internal error", http.StatusInternalServerError)
+	}
 }

internal/handlers/imageenc_internal_test.go

@@ -6,13 +6,11 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"testing"
-	"time"
 
 	"github.com/go-chi/chi/v5"
 
 	"sneak.berlin/go/pixa/internal/encurl"
 	"sneak.berlin/go/pixa/internal/imagerequest"
-	"sneak.berlin/go/pixa/internal/seal"
 )
 
 // newEncTestServer builds a router serving the encrypted-URL route with a
@@ -22,13 +20,11 @@ import (
 func newEncTestServer(t *testing.T) (*encurl.Generator, http.Handler) {
 	t.Helper()
 
-	keys, err := seal.DeriveKeys(testSigningKey)
+	encGen, err := encurl.NewGenerator(testSigningKey)
 	if err != nil {
-		t.Fatalf("seal.DeriveKeys() error = %v", err)
+		t.Fatalf("encurl.NewGenerator() error = %v", err)
 	}
 
-	encGen := encurl.NewGenerator(keys.EncryptedURLKey)
-
 	h := &Handlers{
 		log:    slog.New(slog.DiscardHandler),
 		encGen: encGen,
@@ -66,7 +62,7 @@ func TestHandleImageEnc_OverLimitDimension_Returns400(t *testing.T) {
 		Transform: imagerequest.Transform{
 			Size: imagerequest.Size{Width: 100000, Height: 100000},
 		},
-	}, time.Time{})
+	})
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}
@@ -95,7 +91,7 @@ func TestHandleImageEnc_InvalidFitMode_Returns400(t *testing.T) {
 			Size:    imagerequest.Size{Width: 800, Height: 600},
 			FitMode: imagerequest.Fit("bogus"),
 		},
-	}, time.Time{})
+	})
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}

internal/handlers/imageenc_token_internal_test.go

@@ -10,7 +10,6 @@ import (
 
 	"sneak.berlin/go/pixa/internal/encurl"
 	"sneak.berlin/go/pixa/internal/imagerequest"
-	"sneak.berlin/go/pixa/internal/seal"
 )
 
 // requireServedPhoto requires that rec answers 200 with the JPEG at photoPath
@@ -71,24 +70,25 @@ func TestHandleImageEnc_RejectedToken(t *testing.T) {
 		},
 	}
 
-	valid, err := h.encGen.Generate(&photo, time.Time{})
+	valid, err := h.encGen.Generate(&photo)
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}
 
-	expired, err := h.encGen.Generate(&photo, time.Now().Add(-time.Minute))
+	expiredPhoto := photo
+	expiredPhoto.Expires = time.Now().Add(-time.Minute)
+
+	expired, err := h.encGen.Generate(&expiredPhoto)
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}
 
-	keys, err := seal.DeriveKeys("another-signing-key-fedcba9876543210")
+	otherGen, err := encurl.NewGenerator("another-signing-key-fedcba9876543210")
 	if err != nil {
-		t.Fatalf("seal.DeriveKeys() error = %v", err)
+		t.Fatalf("encurl.NewGenerator() error = %v", err)
 	}
 
-	otherGen := encurl.NewGenerator(keys.EncryptedURLKey)
-
-	otherKey, err := otherGen.Generate(&photo, time.Time{})
+	otherKey, err := otherGen.Generate(&photo)
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}

internal/handlers/jpegxl_default_internal_test.go

@@ -69,7 +69,8 @@ func TestImageWithoutFormat_SignedAsJXL(t *testing.T) {
 			Quality: encurl.DefaultQuality,
 			FitMode: imagerequest.FitCover,
 		},
-	}, expires)
+		Expires: expires,
+	})
 	query := fmt.Sprintf("?sig=%s&exp=%d", sig, expires.Unix())
 
 	for _, size := range []string{"50x50.jxl", "50x50"} {
@@ -93,7 +94,7 @@ func TestImageEncWithoutFormat_ServesJPEGXL(t *testing.T) {
 		Transform: imagerequest.Transform{
 			Size: imagerequest.Size{Width: 50, Height: 50},
 		},
-	}, time.Time{})
+	})
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}

internal/handlers/referer_blocklist_internal_test.go

@@ -10,16 +10,10 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/v5"
-	"github.com/prometheus/client_golang/prometheus"
 	"sneak.berlin/go/pixa/internal/allowlist"
 	"sneak.berlin/go/pixa/internal/encurl"
 	"sneak.berlin/go/pixa/internal/httpfetcher"
-	"sneak.berlin/go/pixa/internal/imageprocessor"
-	"sneak.berlin/go/pixa/internal/imageproxy"
-	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/imgcache"
-	"sneak.berlin/go/pixa/internal/seal"
-	"sneak.berlin/go/pixa/internal/signature"
 )
 
 // blockedReferer is a page on leech.example, which newRefererRoutes puts on
@@ -35,11 +29,11 @@ type countingFetcher struct {
 
 // Fetch counts the fetch and passes it on.
 func (f *countingFetcher) Fetch(
-	ctx context.Context, source imagerequest.Source,
+	ctx context.Context, url string,
 ) (*httpfetcher.FetchResult, error) {
 	f.fetches.Add(1)
 
-	return f.Fetcher.Fetch(ctx, source)
+	return f.Fetcher.Fetch(ctx, url)
 }
 
 // newRefererRoutes returns both image routes of a Handlers whose
@@ -53,41 +47,33 @@ func newRefererRoutes(t *testing.T) (http.Handler, *Handlers, *countingFetcher)
 		Fetcher: newPhotoFetcher(t, allowlistedHost, signedHost),
 	}
 
-	cache, err := imgcache.NewCache(setupTestDB(t), imgcache.Config{
+	cache, err := imgcache.NewCache(setupTestDB(t), imgcache.CacheConfig{
 		StateDir:    t.TempDir(),
 		NegativeTTL: 5 * time.Minute,
-		MaxBytes:    1 << 30,
-	}, prometheus.NewRegistry())
+	})
 	if err != nil {
 		t.Fatalf("imgcache.NewCache() error = %v", err)
 	}
 
-	svc, err := imageproxy.New(&imageproxy.Config{
-		Cache:   cache,
-		Fetcher: fetcher,
-		Processor: imageprocessor.New(imageprocessor.Params{
-			MaxInputBytes:           50 << 20,
-			MaxConcurrentProcessing: 2,
-		}),
-		MaxResponseSize: 50 << 20,
-	}, prometheus.NewRegistry())
+	svc, err := imgcache.NewService(&imgcache.ServiceConfig{
+		Cache:      cache,
+		Fetcher:    fetcher,
+		SigningKey: testSigningKey,
+		Allowlist:  []string{allowlistedHost},
+	})
 	if err != nil {
-		t.Fatalf("imageproxy.New() error = %v", err)
+		t.Fatalf("imgcache.NewService() error = %v", err)
 	}
 
-	keys, err := seal.DeriveKeys(testSigningKey)
+	encGen, err := encurl.NewGenerator(testSigningKey)
 	if err != nil {
-		t.Fatalf("seal.DeriveKeys() error = %v", err)
+		t.Fatalf("encurl.NewGenerator() error = %v", err)
 	}
 
-	encGen := encurl.NewGenerator(keys.EncryptedURLKey)
-
 	h := &Handlers{
-		log:       slog.New(slog.DiscardHandler),
-		imgSvc:    svc,
-		encGen:    encGen,
-		signer:    signature.New(testSigningKey),
-		allowlist: allowlist.New([]string{allowlistedHost}),
+		log:    slog.New(slog.DiscardHandler),
+		imgSvc: svc,
+		encGen: encGen,
 		refererBlocklist: allowlist.New(
 			[]string{"leech.example", ".hotlinker.example"}),
 	}

internal/handlers/request_id_internal_test.go

@@ -17,13 +17,11 @@ import (
 )
 
 // signedPhotoURL returns a signed /v1/image/ URL, valid for a minute, for the
-// JPEG at photoPath on signedHost at 50x50. It is signed with testSigningKey,
-// the key the handlers that newSignedHostServer builds check signatures with.
-// It takes a Handlers it does not use, so that it has the type of encPhotoURL.
-func signedPhotoURL(t *testing.T, _ *Handlers) string {
+// JPEG at photoPath on signedHost at 50x50, made with h's image service.
+func signedPhotoURL(t *testing.T, h *Handlers) string {
 	t.Helper()
 
-	return generateSignedURL(testSigningKey, &imagerequest.Request{
+	signedURL, err := h.imgSvc.GenerateSignedURL("", &imagerequest.Request{
 		Source: imagerequest.Source{
 			Host: signedHost,
 			Path: photoPath,
@@ -33,6 +31,11 @@ func signedPhotoURL(t *testing.T, _ *Handlers) string {
 			Format: imagerequest.FormatJPEG,
 		},
 	}, time.Minute)
+	if err != nil {
+		t.Fatalf("GenerateSignedURL() error = %v", err)
+	}
+
+	return signedURL
 }
 
 // encPhotoURL returns an encrypted /v1/e/ URL, which never expires, for the
@@ -49,7 +52,7 @@ func encPhotoURL(t *testing.T, h *Handlers) string {
 			Size:   imagerequest.Size{Width: 50, Height: 50},
 			Format: imagerequest.FormatJPEG,
 		},
-	}, time.Time{})
+	})
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}

internal/handlers/server_busy_internal_test.go

@@ -11,14 +11,13 @@ import (
 
 	"sneak.berlin/go/pixa/internal/httpfetcher"
 	"sneak.berlin/go/pixa/internal/imageprocessor"
-	"sneak.berlin/go/pixa/internal/imageproxy"
 	"sneak.berlin/go/pixa/internal/imagerequest"
+	"sneak.berlin/go/pixa/internal/imgcache"
 )
 
-// TestServerBusyAnswers503 checks that respondImageError, which answers the
-// errors of both image routes, answers 503 with a clear error when the image
-// service gives up waiting for a free upstream connection or processing slot,
-// wrapped as the service wraps them.
+// TestServerBusyAnswers503 checks that both image routes answer 503 with
+// a clear error when the image service gives up waiting for a free upstream
+// connection or processing slot, wrapped as the service wraps them.
 func TestServerBusyAnswers503(t *testing.T) {
 	t.Parallel()
 
@@ -31,44 +30,61 @@ func TestServerBusyAnswers503(t *testing.T) {
 		fmt.Errorf("upstream fetch failed: %w", httpfetcher.ErrTooManyConnections),
 		fmt.Errorf("image processing failed: %w", imageprocessor.ErrTooManyImages),
 	} {
-		rec := httptest.NewRecorder()
-		h.respondImageError(rec, req, err)
+		plain := httptest.NewRecorder()
+		h.respondImageError(plain, req, err)
 
-		if rec.Code != http.StatusServiceUnavailable {
-			t.Errorf("for %v: status = %d, want %d",
-				err, rec.Code, http.StatusServiceUnavailable)
-		}
+		encrypted := httptest.NewRecorder()
+		h.handleImageError(encrypted, err)
 
-		if !strings.Contains(rec.Body.String(), "server busy, try again later") {
-			t.Errorf("for %v: body = %q, want the server busy error",
-				err, rec.Body.String())
+		for route, rec := range map[string]*httptest.ResponseRecorder{
+			"/v1/image/": plain, "/v1/e/": encrypted,
+		} {
+			if rec.Code != http.StatusServiceUnavailable {
+				t.Errorf("%s for %v: status = %d, want %d",
+					route, err, rec.Code, http.StatusServiceUnavailable)
+			}
+
+			if !strings.Contains(rec.Body.String(), "server busy, try again later") {
+				t.Errorf("%s for %v: body = %q, want the server busy error",
+					route, err, rec.Body.String())
+			}
 		}
 	}
 }
 
-// TestProcessingTimedOutAnswers503 checks that respondImageError, which
-// answers the errors of both image routes, answers 503 with the server busy
-// error when the image service reports that processing stopped at the
-// deadline of the request doing it, wrapped as the service wraps it. A request
-// that waited for that processing gets this error while its own deadline may
-// have time left. The request's source only goes into a log line, so it is
-// left empty.
+// TestProcessingTimedOutAnswers503 checks that respondImageError and
+// handleImageError, which answer the errors of the two image routes, answer
+// 503 with the server busy error when the image service reports that
+// processing stopped at the deadline of the request doing it, wrapped as the
+// service wraps it. A request that waited for that processing gets this error
+// while its own deadline may have time left. The request's source only goes
+// into a log line, so it is left empty.
 func TestProcessingTimedOutAnswers503(t *testing.T) {
 	t.Parallel()
 
 	h := &Handlers{log: slog.New(slog.DiscardHandler)}
 	err := fmt.Errorf("%w: failed to encode: %w",
-		imageproxy.ErrProcessingTimedOut, context.DeadlineExceeded)
+		imgcache.ErrProcessingTimedOut, context.DeadlineExceeded)
 
-	rec := httptest.NewRecorder()
-	h.respondImageError(rec, &imagerequest.Request{}, err)
-	t.Logf("status = %d, body = %q", rec.Code, rec.Body.String())
+	plain := httptest.NewRecorder()
+	h.respondImageError(plain, &imagerequest.Request{}, err)
 
-	if rec.Code != http.StatusServiceUnavailable {
-		t.Errorf("status = %d, want %d", rec.Code, http.StatusServiceUnavailable)
-	}
+	encrypted := httptest.NewRecorder()
+	h.handleImageError(encrypted, err)
 
-	if !strings.Contains(rec.Body.String(), "server busy, try again later") {
-		t.Errorf("body = %q, want the server busy error", rec.Body.String())
+	for name, rec := range map[string]*httptest.ResponseRecorder{
+		"respondImageError": plain, "handleImageError": encrypted,
+	} {
+		t.Logf("%s: status = %d, body = %q", name, rec.Code, rec.Body.String())
+
+		if rec.Code != http.StatusServiceUnavailable {
+			t.Errorf("%s: status = %d, want %d",
+				name, rec.Code, http.StatusServiceUnavailable)
+		}
+
+		if !strings.Contains(rec.Body.String(), "server busy, try again later") {
+			t.Errorf("%s: body = %q, want the server busy error",
+				name, rec.Body.String())
+		}
 	}
 }

internal/handlers/unsupported_source_internal_test.go

@@ -13,11 +13,10 @@ import (
 	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
-// TestUnsupportedSourceFormatAnswers415 checks that respondImageError, which
-// answers the errors of both image routes, answers 415 with a clear error when
-// the upstream answers with a content type pixa does not accept, such as SVG,
-// and when libvips does not read a source as the format its first bytes
-// show, wrapped as the service wraps them.
+// TestUnsupportedSourceFormatAnswers415 checks that both image routes answer
+// 415 with a clear error when the upstream answers with a content type pixa
+// does not accept, such as SVG, and when orig is asked of a source in a
+// format the processor cannot name, wrapped as the service wraps them.
 func TestUnsupportedSourceFormatAnswers415(t *testing.T) {
 	t.Parallel()
 
@@ -29,21 +28,29 @@ func TestUnsupportedSourceFormatAnswers415(t *testing.T) {
 	for _, err := range []error{
 		fmt.Errorf("upstream fetch failed: %w: image/svg+xml",
 			httpfetcher.ErrInvalidContentType),
-		fmt.Errorf("image processing failed: %w: libvips does not read the input as avif",
+		fmt.Errorf("image processing failed: %w: unknown",
 			imageprocessor.ErrUnsupportedInputFormat),
 	} {
-		rec := httptest.NewRecorder()
-		h.respondImageError(rec, req, err)
-		t.Logf("for %v: %d %s", err, rec.Code, rec.Body.String())
+		plain := httptest.NewRecorder()
+		h.respondImageError(plain, req, err)
 
-		if rec.Code != http.StatusUnsupportedMediaType {
-			t.Errorf("for %v: status = %d, want %d",
-				err, rec.Code, http.StatusUnsupportedMediaType)
-		}
+		encrypted := httptest.NewRecorder()
+		h.handleImageError(encrypted, err)
 
-		if !strings.Contains(rec.Body.String(), "unsupported source format") {
-			t.Errorf("for %v: body = %q, want the unsupported source format error",
-				err, rec.Body.String())
+		for route, rec := range map[string]*httptest.ResponseRecorder{
+			"HandleImage": plain, "HandleImageEnc": encrypted,
+		} {
+			t.Logf("%s for %v: %d %s", route, err, rec.Code, rec.Body.String())
+
+			if rec.Code != http.StatusUnsupportedMediaType {
+				t.Errorf("%s for %v: status = %d, want %d",
+					route, err, rec.Code, http.StatusUnsupportedMediaType)
+			}
+
+			if !strings.Contains(rec.Body.String(), "unsupported source format") {
+				t.Errorf("%s for %v: body = %q, want the unsupported source format error",
+					route, err, rec.Body.String())
+			}
 		}
 	}
 }

internal/handlers/validate_signature_internal_test.go

@@ -1,211 +0,0 @@
-package handlers
-
-import (
-	"testing"
-	"time"
-
-	"sneak.berlin/go/pixa/internal/allowlist"
-	"sneak.berlin/go/pixa/internal/signature"
-)
-
-// Addresses the port tests below put on the allowlist.
-const (
-	allowlistedIPv4 = "203.0.113.5"
-	allowlistedIPv6 = "2001:db8::1"
-)
-
-// newSignatureChecker returns Handlers that check signatures with
-// testSigningKey and have allowlistHosts on their allowlist, as New builds
-// them from signing_key and allowlist_hosts.
-func newSignatureChecker(allowlistHosts ...string) *Handlers {
-	return &Handlers{
-		signer:    signature.New(testSigningKey),
-		allowlist: allowlist.New(allowlistHosts),
-	}
-}
-
-func TestValidateSignature_NonAllowlistedHost_NoSignature(t *testing.T) {
-	t.Parallel()
-
-	h := newSignatureChecker(allowlistedHost)
-
-	// Should fail validation - not allowlisted and no signature
-	err := h.validateSignature(photoRequest(signedHost), "", time.Time{})
-	if err == nil {
-		t.Error("validateSignature() expected error for non-allowlisted " +
-			"host without signature")
-	}
-}
-
-func TestValidateSignature_NonAllowlistedHost_ValidSignature(t *testing.T) {
-	t.Parallel()
-
-	h := newSignatureChecker(allowlistedHost)
-	req := photoRequest(signedHost)
-
-	// Generate a valid signature
-	expires := time.Now().Add(time.Hour)
-	sig := signature.New(testSigningKey).Sign(req, expires)
-
-	// Should pass validation
-	err := h.validateSignature(req, sig, expires)
-	if err != nil {
-		t.Errorf("validateSignature() error = %v", err)
-	}
-}
-
-func TestValidateSignature_NonAllowlistedHost_ExpiredSignature(t *testing.T) {
-	t.Parallel()
-
-	h := newSignatureChecker(allowlistedHost)
-	req := photoRequest(signedHost)
-
-	// Generate an expired signature
-	expires := time.Now().Add(-time.Hour)
-	sig := signature.New(testSigningKey).Sign(req, expires)
-
-	// Should fail validation
-	err := h.validateSignature(req, sig, expires)
-	if err == nil {
-		t.Error("validateSignature() expected error for expired signature")
-	}
-}
-
-func TestValidateSignature_NonAllowlistedHost_InvalidSignature(t *testing.T) {
-	t.Parallel()
-
-	h := newSignatureChecker(allowlistedHost)
-
-	// Should fail validation
-	err := h.validateSignature(photoRequest(signedHost), "invalid-signature",
-		time.Now().Add(time.Hour))
-	if err == nil {
-		t.Error("validateSignature() expected error for invalid signature")
-	}
-}
-
-// TestValidateSignature_NoAllowlist checks that with no host on the
-// allowlist, a request without a signature fails validation.
-func TestValidateSignature_NoAllowlist(t *testing.T) {
-	t.Parallel()
-
-	h := newSignatureChecker()
-
-	err := h.validateSignature(photoRequest(signedHost), "", time.Time{})
-	if err == nil {
-		t.Error("validateSignature() expected error when no host is allowlisted")
-	}
-}
-
-// TestValidateSignature_SignatureExactHostMatch verifies that
-// validateSignature enforces exact host matching for signatures. A
-// signature for one host must not verify for a different host, even
-// if they share a domain suffix.
-func TestValidateSignature_SignatureExactHostMatch(t *testing.T) {
-	t.Parallel()
-
-	h := newSignatureChecker()
-
-	// Sign a request for signedHost
-	signedReq := photoRequest(signedHost)
-	expires := time.Now().Add(time.Hour)
-	sig := signature.New(testSigningKey).Sign(signedReq, expires)
-
-	// The original request should pass validation
-	t.Run("exact host passes", func(t *testing.T) {
-		t.Parallel()
-
-		err := h.validateSignature(signedReq, sig, expires)
-		if err != nil {
-			t.Errorf("validateSignature() exact host failed: %v", err)
-		}
-	})
-
-	// Try to reuse the signature with different hosts
-	tests := []struct {
-		name string
-		host string
-	}{
-		{"parent domain", "example.com"},
-		{"sibling subdomain", "images.example.com"},
-		{"deeper subdomain", "a." + signedHost},
-		{"evil suffix domain", signedHost + ".evil.com"},
-		{"prefixed host", "evil" + signedHost},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name+" rejected", func(t *testing.T) {
-			t.Parallel()
-
-			err := h.validateSignature(photoRequest(tt.host), sig, expires)
-			if err == nil {
-				t.Errorf("validateSignature() should reject signature for "+
-					"host %q (signed for %q)", tt.host, signedHost)
-			}
-		})
-	}
-}
-
-// TestValidateSignature_HostWithPortNeedsSignature verifies that a host
-// followed by a port, or by a colon with no port, matches no allowlist entry,
-// so that a request for it without a signature is refused, while the same
-// host with no port is allowlisted.
-func TestValidateSignature_HostWithPortNeedsSignature(t *testing.T) {
-	t.Parallel()
-
-	h := newSignatureChecker(allowlistedHost, allowlistedIPv4, allowlistedIPv6)
-
-	tests := []struct {
-		host        string
-		allowlisted bool
-	}{
-		{allowlistedHost, true},
-		{allowlistedHost + ":8443", false},
-		{allowlistedHost + ":443", false},
-		{allowlistedHost + ":", false},
-		{allowlistedIPv4, true},
-		{allowlistedIPv4 + ":8080", false},
-		{"[" + allowlistedIPv6 + "]", true},
-		{"[" + allowlistedIPv6 + "]:8443", false},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.host, func(t *testing.T) {
-			t.Parallel()
-
-			err := h.validateSignature(photoRequest(tt.host), "", time.Time{})
-			t.Logf("validateSignature() for host %q with no signature: %v",
-				tt.host, err)
-
-			if allowlisted := err == nil; allowlisted != tt.allowlisted {
-				t.Errorf("host %q served without a signature = %v, want %v",
-					tt.host, allowlisted, tt.allowlisted)
-			}
-		})
-	}
-}
-
-// TestValidateSignature_UnbracketedIPv6PortNeedsSignature verifies that an
-// allowlisted IPv6 address written without brackets and followed by a port,
-// or by a colon with no port, needs a signature. Go's URL type reads
-// 2001:db8::1:8443 as the host 2001:db8::1 with the port 8443.
-func TestValidateSignature_UnbracketedIPv6PortNeedsSignature(t *testing.T) {
-	t.Parallel()
-
-	h := newSignatureChecker(allowlistedIPv6)
-
-	for _, host := range []string{allowlistedIPv6 + ":8443", allowlistedIPv6 + ":"} {
-		t.Run(host, func(t *testing.T) {
-			t.Parallel()
-
-			err := h.validateSignature(photoRequest(host), "", time.Time{})
-			t.Logf("validateSignature() for host %q with no signature: %v",
-				host, err)
-
-			if err == nil {
-				t.Errorf("host %q served without a signature, want refused",
-					host)
-			}
-		})
-	}
-}

internal/httpfetcher/blocked_networks_internal_test.go

@@ -7,7 +7,6 @@ import (
 	"net/http"
 	"net/netip"
 	"testing"
-	"time"
 )
 
 // TestIsPrivateIPBlocksSpecialRanges covers the internal and special-use
@@ -71,15 +70,12 @@ func transportOf(t *testing.T, f *HTTPFetcher) *http.Transport {
 func TestDialerEnforcesBlockedNetworks(t *testing.T) {
 	t.Parallel()
 
-	transport := transportOf(t, New(&Config{
-		Timeout:               30 * time.Second,
-		MaxResponseSize:       50 << 20,
-		MaxConnectionsPerHost: 20,
-		MaxConnections:        64,
-		// TEST-NET-2 (198.51.100.0/24) is public to the built-in check, so
-		// blocking it can only come from the operator-supplied list.
-		BlockedNetworks: []netip.Prefix{netip.MustParsePrefix("198.51.100.0/24")},
-	}))
+	cfg := DefaultConfig()
+	// TEST-NET-2 (198.51.100.0/24) is public to the built-in check, so
+	// blocking it can only come from the operator-supplied list.
+	cfg.BlockedNetworks = []netip.Prefix{netip.MustParsePrefix("198.51.100.0/24")}
+
+	transport := transportOf(t, New(cfg))
 
 	blocked := []string{
 		"198.51.100.5:80", // operator-supplied range

internal/httpfetcher/dial_context_internal_test.go

@@ -4,7 +4,6 @@ import (
 	"errors"
 	"net"
 	"testing"
-	"time"
 )
 
 // TestNewUsesCheckedDialerWithoutDialContext checks that a fetcher built
@@ -14,12 +13,7 @@ func TestNewUsesCheckedDialerWithoutDialContext(t *testing.T) {
 	t.Parallel()
 
 	srv := startUpstream(t)
-	transport := transportOf(t, New(&Config{
-		Timeout:               30 * time.Second,
-		MaxResponseSize:       50 << 20,
-		MaxConnectionsPerHost: 20,
-		MaxConnections:        64,
-	}))
+	transport := transportOf(t, New(DefaultConfig()))
 
 	addr := srv.Listener.Addr().String()
 
@@ -38,25 +32,21 @@ func TestDialContextReplacesOnlyTheDialer(t *testing.T) {
 	srv := startUpstream(t)
 	dialer := &recordingDialer{target: srv.Listener.Addr().String()}
 
-	f := New(&Config{
-		Timeout:               30 * time.Second,
-		MaxResponseSize:       50 << 20,
-		AllowHTTP:             true,
-		MaxConnectionsPerHost: 20,
-		MaxConnections:        64,
-		DialContext:           dialer.dialContext,
-	})
+	cfg := DefaultConfig()
+	cfg.AllowHTTP = true
+	cfg.DialContext = dialer.dialContext
+	f := New(cfg)
 
 	if body := fetchBody(t, f, "/image"); body != imagePayload {
 		t.Errorf("body = %q, want %q", body, imagePayload)
 	}
 
-	_, err := f.Fetch(testContext(t), imageSourceOn("127.0.0.1"))
+	_, err := f.Fetch(testContext(t), "http://127.0.0.1/image")
 	if !errors.Is(err, ErrSSRFBlocked) {
 		t.Errorf("Fetch(loopback URL) error = %v, want ErrSSRFBlocked", err)
 	}
 
-	_, err = f.Fetch(testContext(t), upstreamSource("/redirect/private"))
+	_, err = f.Fetch(testContext(t), upstreamURL("/redirect/private"))
 	if !errors.Is(err, ErrSSRFBlocked) {
 		t.Errorf("Fetch(/redirect/private) error = %v, want ErrSSRFBlocked", err)
 	}

internal/httpfetcher/fetch_internal_test.go

@@ -14,8 +14,6 @@ import (
 	"sync"
 	"testing"
 	"time"
-
-	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // testPublicHost is a TEST-NET-1 (RFC 5737) literal. isPrivateIP treats it as
@@ -31,9 +29,9 @@ const imagePayload = "fake-jpeg-bytes"
 // would mean SSRF protection let a forbidden target reach the transport.
 var errUnexpectedDial = errors.New("unexpected dial target")
 
-// upstreamSource returns the source at path on the fake public host.
-func upstreamSource(path string) imagerequest.Source {
-	return imagerequest.Source{Host: testPublicHost, Path: path}
+// upstreamURL builds a fetch URL on the fake public host for the given path.
+func upstreamURL(path string) string {
+	return "http://" + testPublicHost + path
 }
 
 // recordingDialer records every address the transport asks it to dial and
@@ -83,7 +81,7 @@ func startUpstream(t *testing.T) *httptest.Server {
 
 	mux := http.NewServeMux()
 	mux.HandleFunc("/image", func(w http.ResponseWriter, _ *http.Request) {
-		w.Header().Set("Content-Type", imagerequest.FormatJPEG.MIMEType())
+		w.Header().Set("Content-Type", contentTypeJPEG)
 		_, _ = io.WriteString(w, imagePayload)
 	})
 	mux.HandleFunc("/status/500", func(w http.ResponseWriter, _ *http.Request) {
@@ -122,12 +120,7 @@ func newServerFetcher(
 	t.Helper()
 
 	if cfg == nil {
-		cfg = &Config{
-			Timeout:               30 * time.Second,
-			MaxResponseSize:       50 << 20,
-			MaxConnectionsPerHost: 20,
-			MaxConnections:        64,
-		}
+		cfg = DefaultConfig()
 	}
 
 	cfg.AllowHTTP = true
@@ -160,7 +153,7 @@ func testContext(t *testing.T) context.Context {
 func fetchImage(t *testing.T, f *HTTPFetcher, path string) *FetchResult {
 	t.Helper()
 
-	res, err := f.Fetch(testContext(t), upstreamSource(path))
+	res, err := f.Fetch(testContext(t), upstreamURL(path))
 	if err != nil {
 		t.Fatalf("Fetch(%s) error = %v", path, err)
 	}
@@ -172,7 +165,7 @@ func fetchImage(t *testing.T, f *HTTPFetcher, path string) *FetchResult {
 func fetchExpectError(t *testing.T, f *HTTPFetcher, path string) error {
 	t.Helper()
 
-	res, err := f.Fetch(testContext(t), upstreamSource(path))
+	res, err := f.Fetch(testContext(t), upstreamURL(path))
 	if err == nil {
 		_ = res.Content.Close()
 
@@ -224,7 +217,7 @@ func TestFetchRedirectToPrivateIPBlocked(t *testing.T) {
 	srv := startUpstream(t)
 	f, dialer := newServerFetcher(t, srv, nil)
 
-	_, err := f.Fetch(testContext(t), upstreamSource("/redirect/private"))
+	_, err := f.Fetch(testContext(t), upstreamURL("/redirect/private"))
 	if !errors.Is(err, ErrSSRFBlocked) {
 		t.Fatalf("Fetch() error = %v, want ErrSSRFBlocked", err)
 	}
@@ -287,12 +280,8 @@ func TestFetchMaxResponseSizeEnforced(t *testing.T) {
 
 	srv := startUpstream(t)
 
-	cfg := &Config{
-		Timeout:               30 * time.Second,
-		MaxResponseSize:       8,
-		MaxConnectionsPerHost: 20,
-		MaxConnections:        64,
-	}
+	cfg := DefaultConfig()
+	cfg.MaxResponseSize = 8
 
 	f, _ := newServerFetcher(t, srv, cfg)
 
@@ -321,12 +310,8 @@ func fetchWithMaxResponseSize(
 	srv := httptest.NewServer(handler)
 	t.Cleanup(srv.Close)
 
-	cfg := &Config{
-		Timeout:               30 * time.Second,
-		MaxResponseSize:       maxResponseSize,
-		MaxConnectionsPerHost: 20,
-		MaxConnections:        64,
-	}
+	cfg := DefaultConfig()
+	cfg.MaxResponseSize = maxResponseSize
 
 	f, _ := newServerFetcher(t, srv, cfg)
 
@@ -358,7 +343,7 @@ func TestFetchContentLengthBodyAtMaxResponseSize(t *testing.T) {
 
 			res := fetchWithMaxResponseSize(t, maxResponseSize,
 				func(w http.ResponseWriter, _ *http.Request) {
-					w.Header().Set("Content-Type", imagerequest.FormatJPEG.MIMEType())
+					w.Header().Set("Content-Type", contentTypeJPEG)
 					w.Header().Set("Content-Length", strconv.Itoa(tc.size))
 					_, _ = io.WriteString(w, body)
 				})
@@ -406,7 +391,7 @@ func TestFetchChunkedBodyAtMaxResponseSize(t *testing.T) {
 
 			res := fetchWithMaxResponseSize(t, maxResponseSize,
 				func(w http.ResponseWriter, r *http.Request) {
-					w.Header().Set("Content-Type", imagerequest.FormatJPEG.MIMEType())
+					w.Header().Set("Content-Type", contentTypeJPEG)
 					_, _ = io.WriteString(w, body)
 					// With no Content-Length, flushing sends the body
 					// chunked; its end is sent when the handler returns.
@@ -451,12 +436,8 @@ func TestFetchSemaphoreReleasedOnError(t *testing.T) {
 
 	srv := startUpstream(t)
 
-	cfg := &Config{
-		Timeout:               30 * time.Second,
-		MaxResponseSize:       50 << 20,
-		MaxConnectionsPerHost: 1,
-		MaxConnections:        64,
-	}
+	cfg := DefaultConfig()
+	cfg.MaxConnectionsPerHost = 1
 
 	f, _ := newServerFetcher(t, srv, cfg)
 
@@ -485,12 +466,8 @@ func assertSlotReleasedByClose(
 
 	srv := startUpstream(t)
 
-	cfg := &Config{
-		Timeout:               30 * time.Second,
-		MaxResponseSize:       50 << 20,
-		MaxConnectionsPerHost: 1,
-		MaxConnections:        64,
-	}
+	cfg := DefaultConfig()
+	cfg.MaxConnectionsPerHost = 1
 
 	f, _ := newServerFetcher(t, srv, cfg)
 
@@ -547,7 +524,7 @@ func TestFetchSemaphoreReleasedOnPartialReadClose(t *testing.T) {
 	})
 }
 
-// The dial-time re-resolution in dialSSRFSafe is what closes the DNS
+// The dial-time re-resolution in ssrfSafeDialer is what closes the DNS
 // rebinding window: even if validateURL saw a public answer earlier, the
 // dialer independently re-checks the address it is about to connect to. A full
 // rebinding simulation (a resolver returning public, then private) would mean
@@ -567,9 +544,9 @@ func TestSSRFSafeDialerBlocksPrivateTarget(t *testing.T) {
 		t.Run(addr, func(t *testing.T) {
 			t.Parallel()
 
-			_, err := dialSSRFSafe(context.Background(), "tcp", addr, nil)
+			_, err := ssrfSafeDialer(context.Background(), "tcp", addr)
 			if !errors.Is(err, ErrSSRFBlocked) {
-				t.Errorf("dialSSRFSafe(%q) = %v, want ErrSSRFBlocked", addr, err)
+				t.Errorf("ssrfSafeDialer(%q) = %v, want ErrSSRFBlocked", addr, err)
 			}
 		})
 	}
@@ -583,7 +560,7 @@ func TestSSRFSafeDialerAllowsPublicTarget(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	cancel()
 
-	_, err := dialSSRFSafe(ctx, "tcp", testPublicHost+":80", nil)
+	_, err := ssrfSafeDialer(ctx, "tcp", testPublicHost+":80")
 	if err == nil {
 		t.Fatal("expected a dial error for an unreachable public target")
 	}
@@ -592,53 +569,3 @@ func TestSSRFSafeDialerAllowsPublicTarget(t *testing.T) {
 		t.Errorf("public target was SSRF-blocked: %v", err)
 	}
 }
-
-// TestFetchSchemeFollowsAllowHTTP checks that the fetcher fetches a source
-// over https, on port 443, unless AllowHTTP is set, and then over http, on
-// port 80. The test server speaks plain HTTP, so only the fetch over http
-// succeeds.
-func TestFetchSchemeFollowsAllowHTTP(t *testing.T) {
-	t.Parallel()
-
-	tests := []struct {
-		allowHTTP bool
-		wantAddr  string
-	}{
-		{false, net.JoinHostPort(testPublicHost, "443")},
-		{true, net.JoinHostPort(testPublicHost, "80")},
-	}
-
-	for _, tt := range tests {
-		t.Run(fmt.Sprintf("AllowHTTP %v", tt.allowHTTP), func(t *testing.T) {
-			t.Parallel()
-
-			srv := startUpstream(t)
-			dialer := &recordingDialer{target: srv.Listener.Addr().String()}
-
-			f := New(&Config{
-				Timeout:               30 * time.Second,
-				MaxResponseSize:       50 << 20,
-				AllowHTTP:             tt.allowHTTP,
-				MaxConnectionsPerHost: 20,
-				MaxConnections:        64,
-				DialContext:           dialer.dialContext,
-			})
-
-			res, err := f.Fetch(testContext(t), upstreamSource("/image"))
-			if err == nil {
-				_ = res.Content.Close()
-			}
-
-			dialed := dialer.dialedAddrs()
-			t.Logf("Fetch(): error %v, dialed %v", err, dialed)
-
-			if served := err == nil; served != tt.allowHTTP {
-				t.Errorf("served = %v, want %v", served, tt.allowHTTP)
-			}
-
-			if len(dialed) != 1 || dialed[0] != tt.wantAddr {
-				t.Errorf("dialed %v, want only %s", dialed, tt.wantAddr)
-			}
-		})
-	}
-}

internal/httpfetcher/httpfetcher.go

@@ -20,24 +20,36 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/v5/middleware"
-	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // Fetcher configuration constants.
 const (
-	DefaultTLSTimeout      = 10 * time.Second
-	DefaultMaxIdleConns    = 100
-	DefaultIdleConnTimeout = 90 * time.Second
-	DefaultMaxRedirects    = 10
+	DefaultFetchTimeout          = 30 * time.Second
+	DefaultMaxResponseSize       = 50 << 20 // 50MB
+	DefaultTLSTimeout            = 10 * time.Second
+	DefaultMaxIdleConns          = 100
+	DefaultIdleConnTimeout       = 90 * time.Second
+	DefaultMaxRedirects          = 10
+	DefaultMaxConnectionsPerHost = 20
+	DefaultMaxConnections        = 64
 )
 
-// userAgent is the User-Agent header sent to upstream servers.
-const userAgent = "pixa/1.0"
-
 // ConnectionWaitTimeout is how long Fetch waits for a free connection when
 // MaxConnections fetches are already in progress.
 const ConnectionWaitTimeout = 10 * time.Second
 
+// MIME content types.
+const (
+	contentTypeJPEG        = "image/jpeg"
+	contentTypePNG         = "image/png"
+	contentTypeGIF         = "image/gif"
+	contentTypeWebP        = "image/webp"
+	contentTypeAVIF        = "image/avif"
+	contentTypeJXL         = "image/jxl"
+	contentTypeSVG         = "image/svg+xml"
+	contentTypeOctetStream = "application/octet-stream"
+)
+
 // Loopback addresses blocked by SSRF protection.
 const (
 	localhostIPv4 = "127.0.0.1"
@@ -80,8 +92,8 @@ var (
 
 // Fetcher retrieves content from upstream origins.
 type Fetcher interface {
-	// Fetch retrieves the content of the source image.
-	Fetch(ctx context.Context, source imagerequest.Source) (*FetchResult, error)
+	// Fetch retrieves content from the given URL.
+	Fetch(ctx context.Context, url string) (*FetchResult, error)
 }
 
 // FetchResult contains the result of fetching from upstream.
@@ -108,29 +120,17 @@ type FetchResult struct {
 	TLSCipherSuite string
 }
 
-// allowedContentTypes returns the content types an upstream response may
-// have, which Fetch also sends as its Accept header: the MIME types of the
-// formats pixa reads.
-func allowedContentTypes() []string {
-	return []string{
-		imagerequest.FormatJPEG.MIMEType(),
-		imagerequest.FormatPNG.MIMEType(),
-		imagerequest.FormatGIF.MIMEType(),
-		imagerequest.FormatWebP.MIMEType(),
-		imagerequest.FormatAVIF.MIMEType(),
-		imagerequest.FormatJXL.MIMEType(),
-	}
-}
-
-// Config holds configuration for the upstream fetcher. Every field but
-// AllowHTTP, BlockedNetworks and DialContext must be set.
+// Config holds configuration for the upstream fetcher.
 type Config struct {
 	// Timeout for upstream requests.
 	Timeout time.Duration
 	// MaxResponseSize is the maximum allowed response body size.
 	MaxResponseSize int64
-	// AllowHTTP makes the fetcher fetch sources over http instead of https,
-	// and follow redirects to http (for testing only).
+	// UserAgent to send to upstream servers.
+	UserAgent string
+	// AllowedContentTypes is an allow list of MIME types to accept.
+	AllowedContentTypes []string
+	// AllowHTTP allows non-TLS connections (for testing only).
 	AllowHTTP bool
 	// MaxConnectionsPerHost limits concurrent connections to each upstream host.
 	MaxConnectionsPerHost int
@@ -147,6 +147,26 @@ type Config struct {
 	DialContext func(ctx context.Context, network, addr string) (net.Conn, error)
 }
 
+// DefaultConfig returns a Config with sensible defaults.
+func DefaultConfig() *Config {
+	return &Config{
+		Timeout:         DefaultFetchTimeout,
+		MaxResponseSize: DefaultMaxResponseSize,
+		UserAgent:       "pixa/1.0",
+		AllowedContentTypes: []string{
+			contentTypeJPEG,
+			contentTypePNG,
+			contentTypeGIF,
+			contentTypeWebP,
+			contentTypeAVIF,
+			contentTypeJXL,
+		},
+		AllowHTTP:             false,
+		MaxConnectionsPerHost: DefaultMaxConnectionsPerHost,
+		MaxConnections:        DefaultMaxConnections,
+	}
+}
+
 // HTTPFetcher implements Fetcher with SSRF protection and connection limits
 // per host and for all hosts together.
 type HTTPFetcher struct {
@@ -174,6 +194,10 @@ type hostSemaphore struct {
 
 // New creates a new HTTPFetcher with SSRF protection.
 func New(config *Config) *HTTPFetcher {
+	if config == nil {
+		config = DefaultConfig()
+	}
+
 	// Unless config.DialContext replaces it, the transport connects with
 	// the SSRF-safe dialer, which re-resolves and re-checks at connect time
 	// (closing the DNS-rebinding window) against both the built-in ranges
@@ -202,7 +226,7 @@ func New(config *Config) *HTTPFetcher {
 			}
 
 			// Validate the redirect target
-			err := validateURL(req.Context(), req.URL, config.AllowHTTP)
+			err := validateURL(req.Context(), req.URL.String(), config.AllowHTTP)
 			if err != nil {
 				return fmt.Errorf("redirect blocked: %w", err)
 			}
@@ -220,22 +244,18 @@ func New(config *Config) *HTTPFetcher {
 	}
 }
 
-// Fetch retrieves the source image with SSRF protection, over https, or over
-// http when AllowHTTP is set. When MaxConnections fetches are already in
-// progress, it waits up to ConnectionWaitTimeout for one to finish, then
-// fails with ErrTooManyConnections.
-func (f *HTTPFetcher) Fetch(
-	ctx context.Context, source imagerequest.Source,
-) (*FetchResult, error) {
-	sourceURL := source.URL(f.config.AllowHTTP)
-
+// Fetch retrieves content from the given URL with SSRF protection. When
+// MaxConnections fetches are already in progress, it waits up to
+// ConnectionWaitTimeout for one to finish, then fails with
+// ErrTooManyConnections.
+func (f *HTTPFetcher) Fetch(ctx context.Context, url string) (*FetchResult, error) {
 	// Validate URL before making request
-	err := validateURL(ctx, sourceURL, f.config.AllowHTTP)
+	err := validateURL(ctx, url, f.config.AllowHTTP)
 	if err != nil {
 		return nil, err
 	}
 
-	release, err := f.acquireConnection(ctx, source.Host)
+	release, err := f.acquireConnection(ctx, extractHost(url))
 	if err != nil {
 		return nil, err
 	}
@@ -249,14 +269,19 @@ func (f *HTTPFetcher) Fetch(
 		}
 	}()
 
+	parsedURL, err := neturl.Parse(url)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse URL: %w", err)
+	}
+
 	req := &http.Request{
 		Method: http.MethodGet,
-		URL:    sourceURL,
+		URL:    parsedURL,
 		Header: make(http.Header),
 	}
 
-	req.Header.Set("User-Agent", userAgent)
-	req.Header.Set("Accept", strings.Join(allowedContentTypes(), ", "))
+	req.Header.Set("User-Agent", f.config.UserAgent)
+	req.Header.Set("Accept", strings.Join(f.config.AllowedContentTypes, ", "))
 
 	// The ID of the request this fetch serves, so the fetch can be found in
 	// the upstream host's logs
@@ -435,7 +460,7 @@ func (f *HTTPFetcher) isAllowedContentType(contentType string) bool {
 	// Extract the MIME type without parameters
 	mediaType := strings.TrimSpace(strings.Split(contentType, ";")[0])
 
-	for _, allowed := range allowedContentTypes() {
+	for _, allowed := range f.config.AllowedContentTypes {
 		if strings.EqualFold(mediaType, allowed) {
 			return true
 		}
@@ -445,14 +470,19 @@ func (f *HTTPFetcher) isAllowedContentType(contentType string) bool {
 }
 
 // validateURL checks if a URL is safe to fetch (not internal/private).
-func validateURL(ctx context.Context, fetchURL *neturl.URL, allowHTTP bool) error {
-	if !allowHTTP && fetchURL.Scheme != "https" {
+func validateURL(ctx context.Context, rawURL string, allowHTTP bool) error {
+	if !allowHTTP && !strings.HasPrefix(rawURL, "https://") {
 		return ErrUnsupportedScheme
 	}
 
+	parsedURL, err := neturl.Parse(rawURL)
+	if err != nil {
+		return fmt.Errorf("%w: %w", ErrInvalidHost, err)
+	}
+
 	// Hostname drops any port, and the brackets of an IPv6 address whether
 	// or not a port follows them
-	host := fetchURL.Hostname()
+	host := parsedURL.Hostname()
 	if host == "" {
 		return ErrInvalidHost
 	}
@@ -478,6 +508,25 @@ func validateURL(ctx context.Context, fetchURL *neturl.URL, allowHTTP bool) erro
 	return nil
 }
 
+// extractHost extracts the host from a URL string.
+func extractHost(rawURL string) string {
+	// Simple extraction without full URL parsing
+	url := rawURL
+	if idx := strings.Index(url, "://"); idx != -1 {
+		url = url[idx+3:]
+	}
+
+	if idx := strings.Index(url, "/"); idx != -1 {
+		url = url[:idx]
+	}
+
+	if idx := strings.Index(url, "?"); idx != -1 {
+		url = url[:idx]
+	}
+
+	return url
+}
+
 // isLocalhost checks if the host is localhost.
 func isLocalhost(host string) bool {
 	host = strings.ToLower(host)
@@ -590,6 +639,13 @@ func ipv4CompatibleToIPv4(ip net.IP) net.IP {
 	return ip
 }
 
+// ssrfSafeDialer validates IP addresses against the built-in blocked ranges
+// before connecting. New wraps dialSSRFSafe with the operator-supplied
+// blocklist; this entry point enforces the built-in ranges alone.
+func ssrfSafeDialer(ctx context.Context, network, addr string) (net.Conn, error) {
+	return dialSSRFSafe(ctx, network, addr, nil)
+}
+
 // dialSSRFSafe re-resolves addr and refuses to connect to any built-in
 // internal range or operator-supplied blocked prefix, closing the
 // DNS-rebinding window at connect time.

internal/httpfetcher/httpfetcher_internal_test.go

@@ -5,34 +5,70 @@ import (
 	"errors"
 	"io"
 	"net"
-	"net/url"
 	"testing"
 	"testing/fstest"
-	"time"
-
-	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // testHost is the hostname used by mock fetch tests.
 const testHost = "example.com"
 
+func TestDefaultConfig(t *testing.T) {
+	t.Parallel()
+
+	cfg := DefaultConfig()
+
+	if cfg.Timeout != DefaultFetchTimeout {
+		t.Errorf("Timeout = %v, want %v", cfg.Timeout, DefaultFetchTimeout)
+	}
+
+	if cfg.MaxResponseSize != DefaultMaxResponseSize {
+		t.Errorf("MaxResponseSize = %d, want %d", cfg.MaxResponseSize, DefaultMaxResponseSize)
+	}
+
+	if cfg.MaxConnectionsPerHost != DefaultMaxConnectionsPerHost {
+		t.Errorf("MaxConnectionsPerHost = %d, want %d",
+			cfg.MaxConnectionsPerHost, DefaultMaxConnectionsPerHost)
+	}
+
+	if cfg.AllowHTTP {
+		t.Error("AllowHTTP should default to false")
+	}
+
+	if len(cfg.AllowedContentTypes) == 0 {
+		t.Error("AllowedContentTypes should not be empty")
+	}
+}
+
+func TestNewWithNilConfigUsesDefaults(t *testing.T) {
+	t.Parallel()
+
+	f := New(nil)
+
+	if f == nil {
+		t.Fatal("New(nil) returned nil")
+	}
+
+	if f.config == nil {
+		t.Fatal("config should be populated from DefaultConfig")
+	}
+
+	if f.config.Timeout != DefaultFetchTimeout {
+		t.Errorf("Timeout = %v, want %v", f.config.Timeout, DefaultFetchTimeout)
+	}
+}
+
 func TestIsAllowedContentType(t *testing.T) {
 	t.Parallel()
 
-	f := New(&Config{
-		Timeout:               30 * time.Second,
-		MaxResponseSize:       50 << 20,
-		MaxConnectionsPerHost: 20,
-		MaxConnections:        64,
-	})
+	f := New(DefaultConfig())
 
 	tests := []struct {
 		contentType string
 		want        bool
 	}{
-		{imagerequest.FormatJPEG.MIMEType(), true},
-		{imagerequest.FormatPNG.MIMEType(), true},
-		{imagerequest.FormatWebP.MIMEType(), true},
+		{contentTypeJPEG, true},
+		{contentTypePNG, true},
+		{contentTypeWebP, true},
 		{"image/jpeg; charset=utf-8", true},
 		{"IMAGE/JPEG", true},
 		{"text/html", false},
@@ -52,6 +88,33 @@ func TestIsAllowedContentType(t *testing.T) {
 	}
 }
 
+func TestExtractHost(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		url  string
+		want string
+	}{
+		{"https://example.com/path", testHost},
+		{"http://example.com:8080/path", "example.com:8080"},
+		{"https://example.com", testHost},
+		{"https://example.com?q=1", testHost},
+		{"example.com/path", testHost},
+		{"", ""},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.url, func(t *testing.T) {
+			t.Parallel()
+
+			got := extractHost(tc.url)
+			if got != tc.want {
+				t.Errorf("extractHost(%q) = %q, want %q", tc.url, got, tc.want)
+			}
+		})
+	}
+}
+
 func TestIsLocalhost(t *testing.T) {
 	t.Parallel()
 
@@ -164,7 +227,7 @@ func TestIsPrivateIPJudgesEmbeddedIPv4Address(t *testing.T) {
 func TestValidateURL_RejectsNonHTTPS(t *testing.T) {
 	t.Parallel()
 
-	err := validateURL(t.Context(), &url.URL{Scheme: "http", Host: testHost}, false)
+	err := validateURL(t.Context(), "http://example.com/path", false)
 	if !errors.Is(err, ErrUnsupportedScheme) {
 		t.Errorf("validateURL http = %v, want ErrUnsupportedScheme", err)
 	}
@@ -174,8 +237,7 @@ func TestValidateURL_AllowsHTTPWhenConfigured(t *testing.T) {
 	t.Parallel()
 
 	// Use a host that won't resolve (explicit .invalid TLD) so we don't hit DNS.
-	err := validateURL(t.Context(),
-		&url.URL{Scheme: "http", Host: "nonexistent.invalid"}, true)
+	err := validateURL(t.Context(), "http://nonexistent.invalid/path", true)
 	// We expect a host resolution error, not ErrUnsupportedScheme.
 	if errors.Is(err, ErrUnsupportedScheme) {
 		t.Error("validateURL with AllowHTTP should not return ErrUnsupportedScheme")
@@ -185,7 +247,7 @@ func TestValidateURL_AllowsHTTPWhenConfigured(t *testing.T) {
 func TestValidateURL_RejectsLocalhost(t *testing.T) {
 	t.Parallel()
 
-	err := validateURL(t.Context(), &url.URL{Scheme: "https", Host: "localhost"}, false)
+	err := validateURL(t.Context(), "https://localhost/path", false)
 	if !errors.Is(err, ErrSSRFBlocked) {
 		t.Errorf("validateURL localhost = %v, want ErrSSRFBlocked", err)
 	}
@@ -194,7 +256,7 @@ func TestValidateURL_RejectsLocalhost(t *testing.T) {
 func TestValidateURL_EmptyHost(t *testing.T) {
 	t.Parallel()
 
-	err := validateURL(t.Context(), &url.URL{Scheme: "https"}, false)
+	err := validateURL(t.Context(), "https:///path", false)
 	if !errors.Is(err, ErrInvalidHost) {
 		t.Errorf("validateURL empty host = %v, want ErrInvalidHost", err)
 	}
@@ -209,15 +271,14 @@ func TestMockFetcher_FetchesFile(t *testing.T) {
 
 	m := NewMock(mockFS)
 
-	result, err := m.Fetch(context.Background(),
-		imagerequest.Source{Host: testHost, Path: "/images/photo.jpg"})
+	result, err := m.Fetch(context.Background(), "https://example.com/images/photo.jpg")
 	if err != nil {
 		t.Fatalf("Fetch() error = %v", err)
 	}
 
 	defer func() { _ = result.Content.Close() }()
 
-	if result.ContentType != imagerequest.FormatJPEG.MIMEType() {
+	if result.ContentType != contentTypeJPEG {
 		t.Errorf("ContentType = %q, want image/jpeg", result.ContentType)
 	}
 
@@ -241,8 +302,7 @@ func TestMockFetcher_MissingFileReturnsUpstreamError(t *testing.T) {
 	mockFS := fstest.MapFS{}
 	m := NewMock(mockFS)
 
-	_, err := m.Fetch(context.Background(),
-		imagerequest.Source{Host: testHost, Path: "/missing.jpg"})
+	_, err := m.Fetch(context.Background(), "https://example.com/missing.jpg")
 	if !errors.Is(err, ErrUpstreamError) {
 		t.Errorf("Fetch() error = %v, want ErrUpstreamError", err)
 	}
@@ -259,7 +319,7 @@ func TestMockFetcher_RespectsContextCancellation(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	cancel()
 
-	_, err := m.Fetch(ctx, imagerequest.Source{Host: testHost, Path: "/photo.jpg"})
+	_, err := m.Fetch(ctx, "https://example.com/photo.jpg")
 	if !errors.Is(err, context.Canceled) {
 		t.Errorf("Fetch() error = %v, want context.Canceled", err)
 	}
@@ -272,13 +332,13 @@ func TestDetectContentTypeFromPath(t *testing.T) {
 		path string
 		want string
 	}{
-		{"foo/bar.jpg", imagerequest.FormatJPEG.MIMEType()},
-		{"foo/bar.JPG", imagerequest.FormatJPEG.MIMEType()},
-		{"foo/bar.jpeg", imagerequest.FormatJPEG.MIMEType()},
-		{"foo/bar.png", imagerequest.FormatPNG.MIMEType()},
-		{"foo/bar.gif", imagerequest.FormatGIF.MIMEType()},
-		{"foo/bar.webp", imagerequest.FormatWebP.MIMEType()},
-		{"foo/bar.avif", imagerequest.FormatAVIF.MIMEType()},
+		{"foo/bar.jpg", contentTypeJPEG},
+		{"foo/bar.JPG", contentTypeJPEG},
+		{"foo/bar.jpeg", contentTypeJPEG},
+		{"foo/bar.png", contentTypePNG},
+		{"foo/bar.gif", contentTypeGIF},
+		{"foo/bar.webp", contentTypeWebP},
+		{"foo/bar.avif", contentTypeAVIF},
 		{"foo/bar.svg", contentTypeSVG},
 		{"foo/bar.bin", contentTypeOctetStream},
 		{"foo/bar", contentTypeOctetStream},

internal/httpfetcher/jpegxl_internal_test.go

@@ -1,26 +1,16 @@
 package httpfetcher
 
-import (
-	"testing"
-	"time"
-)
+import "testing"
 
 // TestJPEGXLContentType verifies that the fetcher accepts an upstream answer
-// of type image/jxl, and that the mock fetcher serves a .jxl file as
-// image/jxl.
+// of type image/jxl by default, and that the mock fetcher serves a .jxl file
+// as image/jxl.
 func TestJPEGXLContentType(t *testing.T) {
 	t.Parallel()
 
 	const jxlType = "image/jxl"
 
-	f := New(&Config{
-		Timeout:               30 * time.Second,
-		MaxResponseSize:       50 << 20,
-		MaxConnectionsPerHost: 20,
-		MaxConnections:        64,
-	})
-
-	if !f.isAllowedContentType(jxlType) {
+	if !New(DefaultConfig()).isAllowedContentType(jxlType) {
 		t.Errorf("isAllowedContentType(%q) = false, want true", jxlType)
 	}
 

internal/httpfetcher/max_connections_internal_test.go

@@ -8,20 +8,22 @@ import (
 	"sync"
 	"testing"
 	"time"
-
-	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
-// imageSourceOn is the fake upstream's image route on host.
-func imageSourceOn(host string) imagerequest.Source {
-	return imagerequest.Source{Host: host, Path: "/image"}
-}
-
-// imageSourceOnPort is the fake upstream's image route on testPublicHost at
+// imageURLOnPort is the fake upstream's image route on testPublicHost at
 // port. Each port is a different host to the per-host limit, while the test
 // dialer sends every port to the one test server.
-func imageSourceOnPort(port int) imagerequest.Source {
-	return imageSourceOn(net.JoinHostPort(testPublicHost, strconv.Itoa(port)))
+func imageURLOnPort(port int) string {
+	return "http://" + net.JoinHostPort(testPublicHost, strconv.Itoa(port)) +
+		"/image"
+}
+
+func TestDefaultConfigMaxConnections(t *testing.T) {
+	t.Parallel()
+
+	if got := DefaultConfig().MaxConnections; got != DefaultMaxConnections {
+		t.Errorf("MaxConnections = %d, want %d", got, DefaultMaxConnections)
+	}
 }
 
 // TestFetchLimitsConnectionsToAllHostsTogether checks that MaxConnections
@@ -35,22 +37,18 @@ func TestFetchLimitsConnectionsToAllHostsTogether(t *testing.T) {
 
 	srv := startUpstream(t)
 
-	cfg := &Config{
-		Timeout:               30 * time.Second,
-		MaxResponseSize:       50 << 20,
-		MaxConnectionsPerHost: 20,
-		MaxConnections:        2,
-	}
+	cfg := DefaultConfig()
+	cfg.MaxConnections = 2
 
 	f, _ := newServerFetcher(t, srv, cfg)
 	f.connectionWaitTimeout = 100 * time.Millisecond
 
-	first, err := f.Fetch(testContext(t), imageSourceOnPort(81))
+	first, err := f.Fetch(testContext(t), imageURLOnPort(81))
 	if err != nil {
 		t.Fatalf("first Fetch() error = %v", err)
 	}
 
-	second, err := f.Fetch(testContext(t), imageSourceOnPort(82))
+	second, err := f.Fetch(testContext(t), imageURLOnPort(82))
 	if err != nil {
 		t.Fatalf("second Fetch() error = %v", err)
 	}
@@ -59,7 +57,7 @@ func TestFetchLimitsConnectionsToAllHostsTogether(t *testing.T) {
 
 	start := time.Now()
 
-	_, err = f.Fetch(testContext(t), imageSourceOnPort(83))
+	_, err = f.Fetch(testContext(t), imageURLOnPort(83))
 	if !errors.Is(err, ErrTooManyConnections) {
 		t.Fatalf("third Fetch() error = %v, want ErrTooManyConnections", err)
 	}
@@ -78,7 +76,7 @@ func TestFetchLimitsConnectionsToAllHostsTogether(t *testing.T) {
 		t.Fatalf("close first body: %v", err)
 	}
 
-	third, err := f.Fetch(testContext(t), imageSourceOnPort(83))
+	third, err := f.Fetch(testContext(t), imageURLOnPort(83))
 	if err != nil {
 		t.Fatalf("Fetch() after a response was closed: error = %v", err)
 	}
@@ -96,16 +94,12 @@ func TestFetchFreesHostSlotWhenContextEndsWaitingForConnection(t *testing.T) {
 
 	srv := startUpstream(t)
 
-	cfg := &Config{
-		Timeout:               30 * time.Second,
-		MaxResponseSize:       50 << 20,
-		MaxConnectionsPerHost: 20,
-		MaxConnections:        1,
-	}
+	cfg := DefaultConfig()
+	cfg.MaxConnections = 1
 
 	f, _ := newServerFetcher(t, srv, cfg)
 
-	first, err := f.Fetch(testContext(t), imageSourceOnPort(81))
+	first, err := f.Fetch(testContext(t), imageURLOnPort(81))
 	if err != nil {
 		t.Fatalf("first Fetch() error = %v", err)
 	}
@@ -115,7 +109,7 @@ func TestFetchFreesHostSlotWhenContextEndsWaitingForConnection(t *testing.T) {
 	ctx, cancel := context.WithTimeout(t.Context(), 100*time.Millisecond)
 	defer cancel()
 
-	_, err = f.Fetch(ctx, imageSourceOnPort(82))
+	_, err = f.Fetch(ctx, imageURLOnPort(82))
 	if !errors.Is(err, context.DeadlineExceeded) {
 		t.Fatalf("second Fetch() error = %v, want context.DeadlineExceeded", err)
 	}
@@ -140,7 +134,7 @@ func TestFetchRemovesIdleHostSemaphores(t *testing.T) {
 
 	for i := range 100 {
 		wg.Go(func() {
-			res, err := f.Fetch(ctx, imageSourceOnPort(1+i%50))
+			res, err := f.Fetch(ctx, imageURLOnPort(1+i%50))
 			if err != nil {
 				t.Errorf("Fetch() error = %v", err)
 
@@ -169,22 +163,19 @@ func TestFetchRemovesHostSemaphoreWhenNoConnection(t *testing.T) {
 
 	srv := startUpstream(t)
 
-	cfg := &Config{
-		Timeout:               30 * time.Second,
-		MaxResponseSize:       50 << 20,
-		MaxConnectionsPerHost: 1,
-		MaxConnections:        1,
-	}
+	cfg := DefaultConfig()
+	cfg.MaxConnections = 1
+	cfg.MaxConnectionsPerHost = 1
 
 	f, _ := newServerFetcher(t, srv, cfg)
 	f.connectionWaitTimeout = 100 * time.Millisecond
 
-	open, err := f.Fetch(testContext(t), imageSourceOnPort(81))
+	open, err := f.Fetch(testContext(t), imageURLOnPort(81))
 	if err != nil {
 		t.Fatalf("first Fetch() error = %v", err)
 	}
 
-	_, err = f.Fetch(testContext(t), imageSourceOnPort(82))
+	_, err = f.Fetch(testContext(t), imageURLOnPort(82))
 	if !errors.Is(err, ErrTooManyConnections) {
 		t.Fatalf("Fetch() from another host: error = %v, "+
 			"want ErrTooManyConnections", err)
@@ -193,7 +184,7 @@ func TestFetchRemovesHostSemaphoreWhenNoConnection(t *testing.T) {
 	ctx, cancel := context.WithTimeout(t.Context(), 100*time.Millisecond)
 	defer cancel()
 
-	_, err = f.Fetch(ctx, imageSourceOnPort(81))
+	_, err = f.Fetch(ctx, imageURLOnPort(81))
 	if !errors.Is(err, context.DeadlineExceeded) {
 		t.Fatalf("Fetch() from the busy host: error = %v, "+
 			"want context.DeadlineExceeded", err)
@@ -205,7 +196,7 @@ func TestFetchRemovesHostSemaphoreWhenNoConnection(t *testing.T) {
 	ctx, cancel = context.WithTimeout(t.Context(), 100*time.Millisecond)
 	defer cancel()
 
-	_, err = f.Fetch(ctx, imageSourceOnPort(83))
+	_, err = f.Fetch(ctx, imageURLOnPort(83))
 	if !errors.Is(err, context.DeadlineExceeded) {
 		t.Fatalf("Fetch() from a host with nothing open: error = %v, "+
 			"want context.DeadlineExceeded", err)
@@ -228,15 +219,15 @@ func TestFetchReleasesConnectionOnError(t *testing.T) {
 	t.Parallel()
 
 	cases := []struct {
-		name   string
-		source imagerequest.Source
-		want   error
+		name string
+		url  string
+		want error
 	}{
-		{"upstream answers 500", upstreamSource("/status/500"), ErrUpstreamError},
-		{"upstream sends HTML", upstreamSource("/html"), ErrInvalidContentType},
+		{"upstream answers 500", upstreamURL("/status/500"), ErrUpstreamError},
+		{"upstream sends HTML", upstreamURL("/html"), ErrInvalidContentType},
 		// 198.51.100.7 (TEST-NET-2) passes the SSRF checks, and the test
 		// dialer refuses every host but testPublicHost.
-		{"connecting fails", imageSourceOn("198.51.100.7"), errUnexpectedDial},
+		{"connecting fails", "http://198.51.100.7/image", errUnexpectedDial},
 	}
 
 	for _, tc := range cases {
@@ -245,17 +236,13 @@ func TestFetchReleasesConnectionOnError(t *testing.T) {
 
 			srv := startUpstream(t)
 
-			cfg := &Config{
-				Timeout:               30 * time.Second,
-				MaxResponseSize:       50 << 20,
-				MaxConnectionsPerHost: 20,
-				MaxConnections:        1,
-			}
+			cfg := DefaultConfig()
+			cfg.MaxConnections = 1
 
 			f, _ := newServerFetcher(t, srv, cfg)
 			f.connectionWaitTimeout = 100 * time.Millisecond
 
-			_, err := f.Fetch(testContext(t), tc.source)
+			_, err := f.Fetch(testContext(t), tc.url)
 			if !errors.Is(err, tc.want) {
 				t.Fatalf("Fetch() error = %v, want %v", err, tc.want)
 			}

internal/httpfetcher/mock.go

@@ -7,14 +7,14 @@ import (
 	"io/fs"
 	"net/http"
 	"strings"
-
-	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
+// errEmptyURLPath is returned when a mock URL has no usable path.
+var errEmptyURLPath = errors.New("empty URL path")
+
 // MockFetcher implements Fetcher using an embedded filesystem.
 // Files are organized as: hostname/path/to/file.ext
-// The source with host example.com and path /images/photo.jpg maps to
-// example.com/images/photo.jpg; the source query is ignored.
+// URLs like https://example.com/images/photo.jpg map to example.com/images/photo.jpg.
 type MockFetcher struct {
 	fs fs.FS
 }
@@ -24,10 +24,8 @@ func NewMock(fsys fs.FS) *MockFetcher {
 	return &MockFetcher{fs: fsys}
 }
 
-// Fetch retrieves the source's content from the mock filesystem.
-func (m *MockFetcher) Fetch(
-	ctx context.Context, source imagerequest.Source,
-) (*FetchResult, error) {
+// Fetch retrieves content from the mock filesystem.
+func (m *MockFetcher) Fetch(ctx context.Context, url string) (*FetchResult, error) {
 	// Check context cancellation
 	select {
 	case <-ctx.Done():
@@ -35,7 +33,11 @@ func (m *MockFetcher) Fetch(
 	default:
 	}
 
-	path := source.Host + source.Path
+	// Parse URL to get filesystem path
+	path, err := urlToFSPath(url)
+	if err != nil {
+		return nil, err
+	}
 
 	// Open the file
 	f, err := m.fs.Open(path)
@@ -66,11 +68,31 @@ func (m *MockFetcher) Fetch(
 	}, nil
 }
 
-// The content types the mock fetcher gives files in no format pixa reads.
-const (
-	contentTypeSVG         = "image/svg+xml"
-	contentTypeOctetStream = "application/octet-stream"
-)
+// urlToFSPath converts a URL to a filesystem path.
+// https://example.com/images/photo.jpg -> example.com/images/photo.jpg
+func urlToFSPath(rawURL string) (string, error) {
+	// Strip scheme
+	url := rawURL
+	if idx := strings.Index(url, "://"); idx != -1 {
+		url = url[idx+3:]
+	}
+
+	// Remove query string
+	if idx := strings.Index(url, "?"); idx != -1 {
+		url = url[:idx]
+	}
+
+	// Remove fragment
+	if idx := strings.Index(url, "#"); idx != -1 {
+		url = url[:idx]
+	}
+
+	if url == "" {
+		return "", errEmptyURLPath
+	}
+
+	return url, nil
+}
 
 // detectContentTypeFromPath returns the MIME type based on file extension.
 func detectContentTypeFromPath(path string) string {
@@ -78,17 +100,17 @@ func detectContentTypeFromPath(path string) string {
 
 	switch {
 	case strings.HasSuffix(path, ".jpg"), strings.HasSuffix(path, ".jpeg"):
-		return imagerequest.FormatJPEG.MIMEType()
+		return contentTypeJPEG
 	case strings.HasSuffix(path, ".png"):
-		return imagerequest.FormatPNG.MIMEType()
+		return contentTypePNG
 	case strings.HasSuffix(path, ".gif"):
-		return imagerequest.FormatGIF.MIMEType()
+		return contentTypeGIF
 	case strings.HasSuffix(path, ".webp"):
-		return imagerequest.FormatWebP.MIMEType()
+		return contentTypeWebP
 	case strings.HasSuffix(path, ".avif"):
-		return imagerequest.FormatAVIF.MIMEType()
+		return contentTypeAVIF
 	case strings.HasSuffix(path, ".jxl"):
-		return imagerequest.FormatJXL.MIMEType()
+		return contentTypeJXL
 	case strings.HasSuffix(path, ".svg"):
 		return contentTypeSVG
 	default:

internal/httpfetcher/request_id_internal_test.go

@@ -8,7 +8,6 @@ import (
 	"testing"
 
 	"github.com/go-chi/chi/v5/middleware"
-	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // TestFetchSendsRequestID verifies that a fetch sends the ID of the request
@@ -26,7 +25,7 @@ func TestFetchSendsRequestID(t *testing.T) {
 		func(w http.ResponseWriter, r *http.Request) {
 			received <- r.Header.Get("X-Request-Id")
 
-			w.Header().Set("Content-Type", imagerequest.FormatJPEG.MIMEType())
+			w.Header().Set("Content-Type", contentTypeJPEG)
 			_, _ = io.WriteString(w, imagePayload)
 		}))
 	t.Cleanup(srv.Close)
@@ -35,7 +34,7 @@ func TestFetchSendsRequestID(t *testing.T) {
 
 	ctx := context.WithValue(testContext(t), middleware.RequestIDKey, requestID)
 
-	res, err := f.Fetch(ctx, upstreamSource("/image"))
+	res, err := f.Fetch(ctx, upstreamURL("/image"))
 	if err != nil {
 		t.Fatalf("Fetch() error = %v", err)
 	}

internal/imageprocessor/avif_too_large_internal_test.go

@@ -39,41 +39,37 @@ func TestImageProcessor_RefusesAVIFAboveMaxPixels(t *testing.T) {
 	tests := []struct {
 		name          string
 		input         []byte
-		sourceFormat  imagerequest.Format
 		format        imagerequest.Format
 		width, height int
 		fit           imagerequest.Fit
 		refused       bool
 	}{
-		{"AVIF at the limit", cutOff, imagerequest.FormatPNG,
-			imagerequest.FormatAVIF, 4096, 4096, imagerequest.FitCover, false},
-		{"AVIF above the limit", cutOff, imagerequest.FormatPNG,
-			imagerequest.FormatAVIF, 4096, 4097, imagerequest.FitCover, true},
-		{"WebP above the AVIF limit", cutOff, imagerequest.FormatPNG,
-			imagerequest.FormatWebP, 4096, 4097, imagerequest.FitCover, false},
+		{"AVIF at the limit", cutOff, imagerequest.FormatAVIF,
+			4096, 4096, imagerequest.FitCover, false},
+		{"AVIF above the limit", cutOff, imagerequest.FormatAVIF,
+			4096, 4097, imagerequest.FitCover, true},
+		{"WebP above the AVIF limit", cutOff, imagerequest.FormatWebP,
+			4096, 4097, imagerequest.FitCover, false},
 		// FitInside does not enlarge, so the output stays 64x32
-		{"AVIF inside a larger size", cutOff, imagerequest.FormatPNG,
-			imagerequest.FormatAVIF, 8192, 8192, imagerequest.FitInside, false},
+		{"AVIF inside a larger size", cutOff, imagerequest.FormatAVIF,
+			8192, 8192, imagerequest.FitInside, false},
 		// FitOutside scales 64x32 by 128 to cover 8192x1: 8192x4096
-		{"AVIF outside a smaller size", cutOff, imagerequest.FormatPNG,
-			imagerequest.FormatAVIF, 8192, 1, imagerequest.FitOutside, true},
+		{"AVIF outside a smaller size", cutOff, imagerequest.FormatAVIF,
+			8192, 1, imagerequest.FitOutside, true},
 		// With no size, the output keeps the source's 4097x4096
 		{"AVIF of the source's size", largeAVIF, imagerequest.FormatAVIF,
-			imagerequest.FormatAVIF, 0, 0, imagerequest.FitCover, true},
-		{"orig of an AVIF source", largeAVIF, imagerequest.FormatAVIF,
-			imagerequest.FormatOriginal, 0, 0, imagerequest.FitCover, true},
-		{"JPEG of the source's size", largeAVIF, imagerequest.FormatAVIF,
-			imagerequest.FormatJPEG, 0, 0, imagerequest.FitCover, false},
+			0, 0, imagerequest.FitCover, true},
+		{"orig of an AVIF source", largeAVIF, imagerequest.FormatOriginal,
+			0, 0, imagerequest.FitCover, true},
+		{"JPEG of the source's size", largeAVIF, imagerequest.FormatJPEG,
+			0, 0, imagerequest.FitCover, false},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			_, err := New(Params{
-				MaxInputBytes:           50 << 20,
-				MaxConcurrentProcessing: 1,
-			}).Process(t.Context(), bytes.NewReader(tt.input), tt.sourceFormat,
+			_, err := New(Params{}).Process(t.Context(), bytes.NewReader(tt.input),
 				&imagerequest.Transform{
 					Size:    imagerequest.Size{Width: tt.width, Height: tt.height},
 					Format:  tt.format,

internal/imageprocessor/computed_side_internal_test.go

@@ -38,11 +38,8 @@ func TestImageProcessor_RefusesComputedSideAboveMaximum(t *testing.T) {
 
 			input := createTestJPEG(t, tt.inputWidth, tt.inputHeight)
 
-			result, err := New(Params{
-				MaxInputBytes:           50 << 20,
-				MaxConcurrentProcessing: 1,
-			}).Process(t.Context(),
-				bytes.NewReader(input), imagerequest.FormatJPEG,
+			result, err := New(Params{}).Process(t.Context(),
+				bytes.NewReader(input),
 				&imagerequest.Transform{
 					Size:    tt.size,
 					Format:  imagerequest.FormatJPEG,
@@ -107,11 +104,8 @@ func TestImageProcessor_ComputedSideIsAtLeastOne(t *testing.T) {
 
 				input := createTestJPEG(t, tt.inputWidth, tt.inputHeight)
 
-				result, err := New(Params{
-					MaxInputBytes:           50 << 20,
-					MaxConcurrentProcessing: 1,
-				}).Process(t.Context(),
-					bytes.NewReader(input), imagerequest.FormatJPEG,
+				result, err := New(Params{}).Process(t.Context(),
+					bytes.NewReader(input),
 					&imagerequest.Transform{
 						Size:    tt.size,
 						Format:  imagerequest.FormatJPEG,

internal/imageprocessor/deadline_internal_test.go

@@ -7,8 +7,6 @@ import (
 	"io"
 	"testing"
 	"time"
-
-	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // readerAfterDeadline is a Process input whose first Read waits until done
@@ -86,10 +84,9 @@ func checkProcessStopsAtDeadline(
 ) {
 	t.Helper()
 
-	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
+	proc := New(Params{MaxConcurrentProcessing: 1})
 
-	result, err := proc.Process(ctx, input, imagerequest.FormatJPEG,
-		smallJPEGTransform())
+	result, err := proc.Process(ctx, input, smallJPEGTransform())
 	if result != nil {
 		t.Logf("Process() made a %dx%d image after its deadline passed",
 			result.Width, result.Height)

internal/imageprocessor/empty_format_internal_test.go

@@ -14,12 +14,9 @@ import (
 func TestImageProcessor_EmptyFormatRefused(t *testing.T) {
 	t.Parallel()
 
-	_, err := New(Params{
-		MaxInputBytes:           50 << 20,
-		MaxConcurrentProcessing: 1,
-	}).Process(
+	_, err := New(Params{}).Process(
 		t.Context(), bytes.NewReader(createTestJPEG(t, 20, 20)),
-		imagerequest.FormatJPEG, &imagerequest.Transform{},
+		&imagerequest.Transform{},
 	)
 	if !errors.Is(err, ErrUnsupportedOutputFormat) {
 		t.Errorf("Process() error = %v, want %v", err, ErrUnsupportedOutputFormat)

internal/imageprocessor/encoder_settings_internal_test.go

@@ -11,18 +11,14 @@ import (
 	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
-// processedSize runs input, an image in sourceFormat, through Process and
-// returns the output's size in bytes.
+// processedSize runs input through Process and returns the output's size in
+// bytes.
 func processedSize(
-	t *testing.T, input []byte, sourceFormat imagerequest.Format,
-	transform *imagerequest.Transform,
+	t *testing.T, input []byte, transform *imagerequest.Transform,
 ) int64 {
 	t.Helper()
 
-	result, err := New(Params{
-		MaxInputBytes:           50 << 20,
-		MaxConcurrentProcessing: 1,
-	}).Process(t.Context(), bytes.NewReader(input), sourceFormat, transform)
+	result, err := New(Params{}).Process(t.Context(), bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)
 	}
@@ -75,7 +71,7 @@ func TestImageProcessor_PNGIsCompressed(t *testing.T) {
 		}
 	}
 
-	size := processedSize(t, encodePNG(t, flat), imagerequest.FormatPNG,
+	size := processedSize(t, encodePNG(t, flat),
 		&imagerequest.Transform{Format: imagerequest.FormatPNG})
 
 	const rawBytes = width * height * 3
@@ -93,7 +89,7 @@ func TestImageProcessor_WebPAtEffort2(t *testing.T) {
 
 	input := createTestJPEG(t, 200, 150)
 
-	size := processedSize(t, input, imagerequest.FormatJPEG,
+	size := processedSize(t, input,
 		&imagerequest.Transform{Format: imagerequest.FormatWebP, Quality: 85})
 
 	want, _, err := decode(t, input).ExportWebp(&vips.WebpExportParams{
@@ -135,7 +131,7 @@ func TestImageProcessor_AVIFAtEffort1(t *testing.T) {
 
 	input := encodePNG(t, source)
 
-	size := processedSize(t, input, imagerequest.FormatPNG,
+	size := processedSize(t, input,
 		&imagerequest.Transform{Format: imagerequest.FormatAVIF, Quality: 85})
 
 	want, _, err := decode(t, input).ExportAvif(&vips.AvifExportParams{
@@ -162,7 +158,7 @@ func TestImageProcessor_JPEGXLAtEffort4(t *testing.T) {
 
 	input := createTestJPEG(t, 200, 150)
 
-	size := processedSize(t, input, imagerequest.FormatJPEG,
+	size := processedSize(t, input,
 		&imagerequest.Transform{Format: imagerequest.FormatJXL, Quality: 85})
 
 	params := vips.NewJxlExportParams()

internal/imageprocessor/fit_cover_internal_test.go

@@ -36,11 +36,8 @@ func TestImageProcessor_FitCoverServesThinSource(t *testing.T) {
 
 			input := createTestJPEG(t, tt.inputWidth, tt.inputHeight)
 
-			result, err := New(Params{
-				MaxInputBytes:           50 << 20,
-				MaxConcurrentProcessing: 1,
-			}).Process(t.Context(),
-				bytes.NewReader(input), imagerequest.FormatJPEG,
+			result, err := New(Params{}).Process(t.Context(),
+				bytes.NewReader(input),
 				&imagerequest.Transform{
 					Size:    tt.size,
 					Format:  imagerequest.FormatJPEG,
@@ -109,11 +106,8 @@ func TestImageProcessor_FitCoverCropsTheCentre(t *testing.T) {
 
 			input := createBandsPNG(t, tt.inputWidth, tt.inputHeight)
 
-			result, err := New(Params{
-				MaxInputBytes:           50 << 20,
-				MaxConcurrentProcessing: 1,
-			}).Process(t.Context(),
-				bytes.NewReader(input), imagerequest.FormatPNG,
+			result, err := New(Params{}).Process(t.Context(),
+				bytes.NewReader(input),
 				&imagerequest.Transform{
 					Size:    imagerequest.Size{Width: 50, Height: 50},
 					Format:  imagerequest.FormatPNG,
@@ -236,11 +230,8 @@ func TestImageProcessor_FitCoverKeepsProportions(t *testing.T) {
 
 			input := createSquarePNG(t, tt.side, tt.squareSide)
 
-			result, err := New(Params{
-				MaxInputBytes:           50 << 20,
-				MaxConcurrentProcessing: 1,
-			}).Process(t.Context(),
-				bytes.NewReader(input), imagerequest.FormatPNG,
+			result, err := New(Params{}).Process(t.Context(),
+				bytes.NewReader(input),
 				&imagerequest.Transform{
 					Size:    tt.size,
 					Format:  imagerequest.FormatPNG,

internal/imageprocessor/fit_outside_internal_test.go

@@ -41,11 +41,8 @@ func TestImageProcessor_RefusesFitOutsideAboveMaximum(t *testing.T) {
 
 			input := createTestJPEG(t, tt.inputWidth, tt.inputHeight)
 
-			result, err := New(Params{
-				MaxInputBytes:           50 << 20,
-				MaxConcurrentProcessing: 1,
-			}).Process(t.Context(),
-				bytes.NewReader(input), imagerequest.FormatJPEG,
+			result, err := New(Params{}).Process(t.Context(),
+				bytes.NewReader(input),
 				&imagerequest.Transform{
 					Size:    tt.size,
 					Format:  imagerequest.FormatJPEG,
@@ -98,11 +95,8 @@ func TestImageProcessor_FitOutsideSideIsAtLeastOne(t *testing.T) {
 
 			input := createTestJPEG(t, tt.inputWidth, tt.inputHeight)
 
-			result, err := New(Params{
-				MaxInputBytes:           50 << 20,
-				MaxConcurrentProcessing: 1,
-			}).Process(t.Context(),
-				bytes.NewReader(input), imagerequest.FormatJPEG,
+			result, err := New(Params{}).Process(t.Context(),
+				bytes.NewReader(input),
 				&imagerequest.Transform{
 					Size:    tt.size,
 					Format:  imagerequest.FormatJPEG,

internal/imageprocessor/imageprocessor.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/davidbyttow/govips/v2/vips"
+	"sneak.berlin/go/pixa/internal/config"
 	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
@@ -70,12 +71,18 @@ type Result struct {
 	InputWidth int
 	// InputHeight is the original image height before processing.
 	InputHeight int
+	// InputFormat is the detected input format (e.g., "jpeg", "png").
+	InputFormat string
 }
 
 // MaxInputDimension is the maximum allowed width or height for input images.
 // Images larger than this are rejected to prevent DoS via decompression bombs.
 const MaxInputDimension = 8192
 
+// DefaultMaxInputBytes is the default maximum input size in bytes (50 MiB).
+// This matches the default upstream fetcher limit.
+const DefaultMaxInputBytes = 50 << 20
+
 // ErrInputTooLarge is returned when input image dimensions exceed MaxInputDimension.
 var ErrInputTooLarge = errors.New("input image dimensions exceed maximum")
 
@@ -111,10 +118,9 @@ var ErrAVIFOutputTooLarge = errors.New("AVIF output has too many pixels")
 var ErrUnsupportedOutputFormat = errors.New("unsupported output format")
 
 // ErrUnsupportedInputFormat is returned, before the input is decoded, when
-// libvips reads the input's first bytes as another format than its source
-// format, or as none. An SVG whose first bytes pass the first-bytes check for
-// AVIF is one example. A source format other than the six pixa reads is also
-// refused with it.
+// libvips reads the input's first bytes as another format than the source
+// formats, or as none: for example an SVG whose first bytes pass the
+// first-bytes check for AVIF.
 var ErrUnsupportedInputFormat = errors.New("unsupported input format")
 
 // ErrTooManyImages is returned when MaxConcurrentProcessing images are being
@@ -136,30 +142,42 @@ type ImageProcessor struct {
 	processingWaitTimeout time.Duration
 }
 
-// Params holds configuration for creating an ImageProcessor. Both fields
-// must be at least 1.
+// Params holds configuration for creating an ImageProcessor.
+// Zero values use sensible defaults (MaxInputBytes defaults to DefaultMaxInputBytes).
 type Params struct {
 	// MaxInputBytes is the maximum allowed input size in bytes.
+	// If <= 0, DefaultMaxInputBytes is used.
 	MaxInputBytes int64
 	// MaxConcurrentProcessing is the most images processed at once.
+	// If <= 0, config.DefaultMaxConcurrentProcessing() is used.
 	MaxConcurrentProcessing int
 }
 
 // New creates a new image processor with the given parameters.
+// A zero-value Params{} uses sensible defaults.
 func New(params Params) *ImageProcessor {
 	initVips()
 
+	maxInputBytes := params.MaxInputBytes
+	if maxInputBytes <= 0 {
+		maxInputBytes = DefaultMaxInputBytes
+	}
+
+	maxConcurrentProcessing := params.MaxConcurrentProcessing
+	if maxConcurrentProcessing <= 0 {
+		maxConcurrentProcessing = config.DefaultMaxConcurrentProcessing()
+	}
+
 	return &ImageProcessor{
-		maxInputBytes:         params.MaxInputBytes,
-		processingSemaphore:   make(chan struct{}, params.MaxConcurrentProcessing),
+		maxInputBytes:         maxInputBytes,
+		processingSemaphore:   make(chan struct{}, maxConcurrentProcessing),
 		processingWaitTimeout: ProcessingWaitTimeout,
 	}
 }
 
-// Process transforms the image read from input according to transform.
-// sourceFormat is the input's format, which magic detected from its first
-// bytes. When MaxConcurrentProcessing images are already being processed,
-// it waits up to ProcessingWaitTimeout for one to finish, then fails with
+// Process transforms an image according to transform. When
+// MaxConcurrentProcessing images are already being processed, it waits up
+// to ProcessingWaitTimeout for one to finish, then fails with
 // ErrTooManyImages. When ctx has ended once Process has a slot, or before it
 // encodes, it returns ctx's error and gives the slot back. govips gives pixa
 // no way to stop libvips once an encode has begun, so an encode keeps its
@@ -168,7 +186,6 @@ func New(params Params) *ImageProcessor {
 func (p *ImageProcessor) Process(
 	ctx context.Context,
 	input io.Reader,
-	sourceFormat imagerequest.Format,
 	transform *imagerequest.Transform,
 ) (*Result, error) {
 	release, err := p.acquireSlot(ctx)
@@ -183,9 +200,13 @@ func (p *ImageProcessor) Process(
 		return nil, err
 	}
 
-	// Input libvips would not load as sourceFormat is refused before it is
-	// decoded
-	err = checkInputFormat(data, sourceFormat)
+	// govips picks the libvips loader from the input's first bytes with
+	// DetermineImageType. Input whose first bytes it reads as no source
+	// format, such as SVG, which librsvg would render, is refused before
+	// libvips reads it.
+	inputFormat := p.detectFormat(vips.DetermineImageType(data))
+
+	sourceFormat, err := p.formatFromString(inputFormat)
 	if err != nil {
 		return nil, err
 	}
@@ -251,11 +272,12 @@ func (p *ImageProcessor) Process(
 	return &Result{
 		Content:       io.NopCloser(bytes.NewReader(output)),
 		ContentLength: int64(len(output)),
-		ContentType:   outputFormat.MIMEType(),
+		ContentType:   FormatToMIME(outputFormat),
 		Width:         img.Width(),
 		Height:        img.Height(),
 		InputWidth:    origWidth,
 		InputHeight:   origHeight,
+		InputFormat:   inputFormat,
 	}, nil
 }
 
@@ -290,6 +312,62 @@ func targetDimensions(
 	return width, height, nil
 }
 
+// MIME types for the supported image formats.
+const (
+	mimeJPEG = "image/jpeg"
+	mimePNG  = "image/png"
+	mimeGIF  = "image/gif"
+	mimeWebP = "image/webp"
+	mimeAVIF = "image/avif"
+	mimeJXL  = "image/jxl"
+)
+
+// SupportedInputFormats returns MIME types this processor can read.
+func (p *ImageProcessor) SupportedInputFormats() []string {
+	return []string{
+		mimeJPEG,
+		mimePNG,
+		mimeGIF,
+		mimeWebP,
+		mimeAVIF,
+		mimeJXL,
+	}
+}
+
+// SupportedOutputFormats returns formats this processor can write.
+func (p *ImageProcessor) SupportedOutputFormats() []imagerequest.Format {
+	return []imagerequest.Format{
+		imagerequest.FormatJPEG,
+		imagerequest.FormatPNG,
+		imagerequest.FormatGIF,
+		imagerequest.FormatWebP,
+		imagerequest.FormatAVIF,
+		imagerequest.FormatJXL,
+	}
+}
+
+// FormatToMIME converts a Format to its MIME type string.
+func FormatToMIME(format imagerequest.Format) string {
+	switch format {
+	case imagerequest.FormatJPEG:
+		return mimeJPEG
+	case imagerequest.FormatPNG:
+		return mimePNG
+	case imagerequest.FormatWebP:
+		return mimeWebP
+	case imagerequest.FormatGIF:
+		return mimeGIF
+	case imagerequest.FormatAVIF:
+		return mimeAVIF
+	case imagerequest.FormatJXL:
+		return mimeJXL
+	case imagerequest.FormatOriginal, imagerequest.FormatAuto:
+		return "application/octet-stream"
+	default:
+		return "application/octet-stream"
+	}
+}
+
 // WaitForProcessing waits until no image is being processed, or until ctx
 // ends, and returns how many images were still being processed then. It
 // waits by taking each slot in processingSemaphore as it frees up until it
@@ -358,49 +436,27 @@ func (p *ImageProcessor) readInput(input io.Reader) ([]byte, error) {
 	return data, nil
 }
 
-// checkInputFormat returns ErrUnsupportedInputFormat unless libvips would
-// load data with the loader of sourceFormat. govips picks the libvips loader
-// from the input's first bytes with DetermineImageType. It refuses an SVG
-// whose first bytes pass the first-bytes check for AVIF, which librsvg would
-// otherwise render.
-func checkInputFormat(data []byte, sourceFormat imagerequest.Format) error {
-	// A format with no loader, such as orig or auto, has the type govips also
-	// gives input it cannot read, which the check below would let through.
-	sourceType := vipsImageType(sourceFormat)
-	if sourceType == vips.ImageTypeUnknown {
-		return fmt.Errorf("%w: %q is not a source format",
-			ErrUnsupportedInputFormat, sourceFormat)
-	}
-
-	if vips.DetermineImageType(data) != sourceType {
-		return fmt.Errorf("%w: libvips does not read the input as %s",
-			ErrUnsupportedInputFormat, sourceFormat)
-	}
-
-	return nil
-}
-
-// vipsImageType returns the govips image type whose libvips loader reads
-// format. orig and auto stand for another format, so they have
-// vips.ImageTypeUnknown, which govips has no loader for.
-func vipsImageType(format imagerequest.Format) vips.ImageType {
-	switch format {
-	case imagerequest.FormatJPEG:
-		return vips.ImageTypeJPEG
-	case imagerequest.FormatPNG:
-		return vips.ImageTypePNG
-	case imagerequest.FormatGIF:
-		return vips.ImageTypeGIF
-	case imagerequest.FormatWebP:
-		return vips.ImageTypeWEBP
-	case imagerequest.FormatAVIF:
-		return vips.ImageTypeAVIF
-	case imagerequest.FormatJXL:
-		return vips.ImageTypeJXL
-	case imagerequest.FormatOriginal, imagerequest.FormatAuto:
-		return vips.ImageTypeUnknown
+// detectFormat returns the format string for a govips image type.
+func (p *ImageProcessor) detectFormat(imageType vips.ImageType) string {
+	switch imageType {
+	case vips.ImageTypeJPEG:
+		return "jpeg"
+	case vips.ImageTypePNG:
+		return "png"
+	case vips.ImageTypeGIF:
+		return "gif"
+	case vips.ImageTypeWEBP:
+		return "webp"
+	case vips.ImageTypeAVIF, vips.ImageTypeHEIF:
+		return string(imagerequest.FormatAVIF)
+	case vips.ImageTypeJXL:
+		return string(imagerequest.FormatJXL)
+	case vips.ImageTypeUnknown, vips.ImageTypeMagick, vips.ImageTypePDF,
+		vips.ImageTypeSVG, vips.ImageTypeTIFF, vips.ImageTypeBMP,
+		vips.ImageTypeJP2K:
+		return "unknown"
 	default:
-		return vips.ImageTypeUnknown
+		return "unknown"
 	}
 }
 
@@ -754,3 +810,26 @@ func jxlDistance(quality int) float64 {
 
 	return 53.0/3000.0*q*q - 23.0/20.0*q + 25.0
 }
+
+// formatFromString converts a format string from detectFormat to Format. A
+// format detectFormat could not name is ErrUnsupportedInputFormat.
+func (p *ImageProcessor) formatFromString(
+	format string,
+) (imagerequest.Format, error) {
+	switch format {
+	case "jpeg":
+		return imagerequest.FormatJPEG, nil
+	case "png":
+		return imagerequest.FormatPNG, nil
+	case "gif":
+		return imagerequest.FormatGIF, nil
+	case "webp":
+		return imagerequest.FormatWebP, nil
+	case string(imagerequest.FormatAVIF):
+		return imagerequest.FormatAVIF, nil
+	case string(imagerequest.FormatJXL):
+		return imagerequest.FormatJXL, nil
+	default:
+		return "", fmt.Errorf("%w: %s", ErrUnsupportedInputFormat, format)
+	}
+}

internal/imageprocessor/imageprocessor_internal_test.go

@@ -94,23 +94,23 @@ func isAVIF(data []byte) bool {
 // detectMIME is a minimal magic-byte detector for test assertions.
 func detectMIME(data []byte) string {
 	if len(data) >= 3 && data[0] == 0xFF && data[1] == 0xD8 && data[2] == 0xFF {
-		return imagerequest.FormatJPEG.MIMEType()
+		return mimeJPEG
 	}
 
 	if len(data) >= 8 && string(data[:8]) == "\x89PNG\r\n\x1a\n" {
-		return imagerequest.FormatPNG.MIMEType()
+		return mimePNG
 	}
 
 	if len(data) >= 4 && string(data[:4]) == "GIF8" {
-		return imagerequest.FormatGIF.MIMEType()
+		return mimeGIF
 	}
 
 	if len(data) >= 12 && string(data[:4]) == "RIFF" && string(data[8:12]) == "WEBP" {
-		return imagerequest.FormatWebP.MIMEType()
+		return mimeWebP
 	}
 
 	if isAVIF(data) {
-		return imagerequest.FormatAVIF.MIMEType()
+		return mimeAVIF
 	}
 
 	return ""
@@ -119,7 +119,7 @@ func detectMIME(data []byte) string {
 func TestImageProcessor_ResizeJPEG(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
+	proc := New(Params{})
 	ctx := context.Background()
 
 	input := createTestJPEG(t, 800, 600)
@@ -131,8 +131,7 @@ func TestImageProcessor_ResizeJPEG(t *testing.T) {
 		FitMode: imagerequest.FitCover,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input),
-		imagerequest.FormatJPEG, transform)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)
 	}
@@ -158,7 +157,7 @@ func TestImageProcessor_ResizeJPEG(t *testing.T) {
 	}
 
 	mime := detectMIME(data)
-	if mime != imagerequest.FormatJPEG.MIMEType() {
+	if mime != mimeJPEG {
 		t.Errorf("Output format = %v, want image/jpeg", mime)
 	}
 }
@@ -166,7 +165,7 @@ func TestImageProcessor_ResizeJPEG(t *testing.T) {
 func TestImageProcessor_ConvertToPNG(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
+	proc := New(Params{})
 	ctx := context.Background()
 
 	input := createTestJPEG(t, 200, 150)
@@ -177,8 +176,7 @@ func TestImageProcessor_ConvertToPNG(t *testing.T) {
 		FitMode: imagerequest.FitCover,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input),
-		imagerequest.FormatJPEG, transform)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)
 	}
@@ -191,7 +189,7 @@ func TestImageProcessor_ConvertToPNG(t *testing.T) {
 	}
 
 	mime := detectMIME(data)
-	if mime != imagerequest.FormatPNG.MIMEType() {
+	if mime != mimePNG {
 		t.Errorf("Output format = %v, want image/png", mime)
 	}
 }
@@ -203,7 +201,7 @@ func processAndCheckSize(
 ) {
 	t.Helper()
 
-	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
+	proc := New(Params{})
 	ctx := context.Background()
 
 	input := createTestJPEG(t, inputW, inputH)
@@ -215,8 +213,7 @@ func processAndCheckSize(
 		FitMode: imagerequest.FitCover,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input),
-		imagerequest.FormatJPEG, transform)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)
 	}
@@ -242,7 +239,7 @@ func TestImageProcessor_OriginalSize(t *testing.T) {
 func TestImageProcessor_FitContain(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
+	proc := New(Params{})
 	ctx := context.Background()
 
 	// 800x400 image (2:1 aspect) into 400x400 box with contain
@@ -256,8 +253,7 @@ func TestImageProcessor_FitContain(t *testing.T) {
 		FitMode: imagerequest.FitContain,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input),
-		imagerequest.FormatJPEG, transform)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)
 	}
@@ -289,7 +285,7 @@ func TestImageProcessor_ProportionalScale_HeightOnly(t *testing.T) {
 func TestImageProcessor_ProcessPNG(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
+	proc := New(Params{})
 	ctx := context.Background()
 
 	input := createTestPNG(t, 400, 300)
@@ -300,8 +296,7 @@ func TestImageProcessor_ProcessPNG(t *testing.T) {
 		FitMode: imagerequest.FitCover,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input),
-		imagerequest.FormatPNG, transform)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)
 	}
@@ -317,6 +312,22 @@ func TestImageProcessor_ProcessPNG(t *testing.T) {
 	}
 }
 
+func TestImageProcessor_SupportedFormats(t *testing.T) {
+	t.Parallel()
+
+	proc := New(Params{})
+
+	inputFormats := proc.SupportedInputFormats()
+	if len(inputFormats) == 0 {
+		t.Error("SupportedInputFormats() returned empty slice")
+	}
+
+	outputFormats := proc.SupportedOutputFormats()
+	if len(outputFormats) == 0 {
+		t.Error("SupportedOutputFormats() returned empty slice")
+	}
+}
+
 func TestImageProcessor_RejectsOversizedInput(t *testing.T) {
 	t.Parallel()
 
@@ -335,7 +346,7 @@ func TestImageProcessor_RejectsOversizedInput(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
+			proc := New(Params{})
 			ctx := context.Background()
 			input := createTestJPEG(t, tt.width, tt.height)
 
@@ -346,8 +357,7 @@ func TestImageProcessor_RejectsOversizedInput(t *testing.T) {
 				FitMode: imagerequest.FitCover,
 			}
 
-			_, err := proc.Process(ctx, bytes.NewReader(input),
-				imagerequest.FormatJPEG, transform)
+			_, err := proc.Process(ctx, bytes.NewReader(input), transform)
 			if err == nil {
 				t.Error("Process() should reject oversized input images")
 			}
@@ -362,7 +372,7 @@ func TestImageProcessor_RejectsOversizedInput(t *testing.T) {
 func TestImageProcessor_AcceptsMaxDimensionInput(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
+	proc := New(Params{})
 	ctx := context.Background()
 
 	// Create an image at exactly MaxInputDimension - should be accepted
@@ -375,8 +385,7 @@ func TestImageProcessor_AcceptsMaxDimensionInput(t *testing.T) {
 		FitMode: imagerequest.FitCover,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input),
-		imagerequest.FormatJPEG, transform)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf(
 			"Process() should accept images at MaxInputDimension, got error: %v",
@@ -394,7 +403,7 @@ func encodeAndCheck(
 ) {
 	t.Helper()
 
-	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
+	proc := New(Params{})
 	ctx := context.Background()
 
 	input := createTestJPEG(t, 200, 150)
@@ -406,8 +415,7 @@ func encodeAndCheck(
 		FitMode: imagerequest.FitCover,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input),
-		imagerequest.FormatJPEG, transform)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v, want nil", err)
 	}
@@ -438,13 +446,13 @@ func encodeAndCheck(
 func TestImageProcessor_EncodeWebP(t *testing.T) {
 	t.Parallel()
 
-	encodeAndCheck(t, imagerequest.FormatWebP, 80, imagerequest.FormatWebP.MIMEType())
+	encodeAndCheck(t, imagerequest.FormatWebP, 80, mimeWebP)
 }
 
 func TestImageProcessor_DecodeAVIF(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
+	proc := New(Params{})
 	ctx := context.Background()
 
 	// Load test AVIF file
@@ -461,8 +469,7 @@ func TestImageProcessor_DecodeAVIF(t *testing.T) {
 		FitMode: imagerequest.FitCover,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input),
-		imagerequest.FormatAVIF, transform)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v, want nil (AVIF decoding should work)", err)
 	}
@@ -476,7 +483,7 @@ func TestImageProcessor_DecodeAVIF(t *testing.T) {
 	}
 
 	mime := detectMIME(data)
-	if mime != imagerequest.FormatJPEG.MIMEType() {
+	if mime != mimeJPEG {
 		t.Errorf("Output format = %v, want image/jpeg", mime)
 	}
 }
@@ -487,7 +494,7 @@ func TestImageProcessor_RejectsOversizedInputData(t *testing.T) {
 	// Create a processor with a very small byte limit
 	const limit = 1024
 
-	proc := New(Params{MaxInputBytes: limit, MaxConcurrentProcessing: 1})
+	proc := New(Params{MaxInputBytes: limit})
 	ctx := context.Background()
 
 	// Create a valid JPEG that exceeds the byte limit
@@ -503,8 +510,7 @@ func TestImageProcessor_RejectsOversizedInputData(t *testing.T) {
 		FitMode: imagerequest.FitCover,
 	}
 
-	_, err := proc.Process(ctx, bytes.NewReader(input),
-		imagerequest.FormatJPEG, transform)
+	_, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err == nil {
 		t.Fatal("Process() should reject input exceeding maxInputBytes")
 	}
@@ -521,7 +527,7 @@ func TestImageProcessor_AcceptsInputWithinLimit(t *testing.T) {
 	input := createTestJPEG(t, 10, 10)
 	limit := int64(len(input)) * 10 // 10× headroom
 
-	proc := New(Params{MaxInputBytes: limit, MaxConcurrentProcessing: 1})
+	proc := New(Params{MaxInputBytes: limit})
 	ctx := context.Background()
 
 	transform := &imagerequest.Transform{
@@ -531,8 +537,7 @@ func TestImageProcessor_AcceptsInputWithinLimit(t *testing.T) {
 		FitMode: imagerequest.FitCover,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input),
-		imagerequest.FormatJPEG, transform)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v, want nil", err)
 	}
@@ -540,25 +545,37 @@ func TestImageProcessor_AcceptsInputWithinLimit(t *testing.T) {
 	defer func() { _ = result.Content.Close() }()
 }
 
+func TestImageProcessor_DefaultMaxInputBytes(t *testing.T) {
+	t.Parallel()
+
+	// Passing 0 should use the default
+	proc := New(Params{})
+	if proc.maxInputBytes != DefaultMaxInputBytes {
+		t.Errorf("maxInputBytes = %d, want %d", proc.maxInputBytes, DefaultMaxInputBytes)
+	}
+
+	// Passing negative should also use the default
+	proc = New(Params{MaxInputBytes: -1})
+	if proc.maxInputBytes != DefaultMaxInputBytes {
+		t.Errorf("maxInputBytes = %d, want %d", proc.maxInputBytes, DefaultMaxInputBytes)
+	}
+}
+
 func TestImageProcessor_EncodeAVIF(t *testing.T) {
 	t.Parallel()
 
-	encodeAndCheck(t, imagerequest.FormatAVIF, 85, imagerequest.FormatAVIF.MIMEType())
+	encodeAndCheck(t, imagerequest.FormatAVIF, 85, mimeAVIF)
 }
 
-// processAndDecode runs input, a JPEG, through Process and decodes the output
-// with vips, so a test can inspect the image a client would receive.
+// processAndDecode runs input through Process and decodes the output with
+// vips, so a test can inspect the image a client would receive.
 func processAndDecode(
 	t *testing.T, input []byte, transform *imagerequest.Transform,
 ) *vips.ImageRef {
 	t.Helper()
 
-	result, err := New(Params{
-		MaxInputBytes:           50 << 20,
-		MaxConcurrentProcessing: 1,
-	}).Process(
-		context.Background(), bytes.NewReader(input), imagerequest.FormatJPEG,
-		transform,
+	result, err := New(Params{}).Process(
+		context.Background(), bytes.NewReader(input), transform,
 	)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)

internal/imageprocessor/jpegxl_output_internal_test.go

@@ -21,12 +21,8 @@ func TestImageProcessor_EncodeJPEGXL(t *testing.T) {
 		Format: imagerequest.FormatJXL,
 	}
 
-	result, err := New(Params{
-		MaxInputBytes:           50 << 20,
-		MaxConcurrentProcessing: 1,
-	}).Process(
-		t.Context(), bytes.NewReader(createTestJPEG(t, 200, 150)),
-		imagerequest.FormatJPEG, transform,
+	result, err := New(Params{}).Process(
+		t.Context(), bytes.NewReader(createTestJPEG(t, 200, 150)), transform,
 	)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)
@@ -68,11 +64,8 @@ func TestImageProcessor_JPEGXLQuality(t *testing.T) {
 	outputBytes := make(map[int]int64)
 
 	for _, quality := range []int{30, 90} {
-		result, err := New(Params{
-			MaxInputBytes:           50 << 20,
-			MaxConcurrentProcessing: 1,
-		}).Process(t.Context(),
-			bytes.NewReader(input), imagerequest.FormatJPEG,
+		result, err := New(Params{}).Process(t.Context(),
+			bytes.NewReader(input),
 			&imagerequest.Transform{Format: imagerequest.FormatJXL, Quality: quality})
 		if err != nil {
 			t.Fatalf("Process() at quality %d error = %v", quality, err)

internal/imageprocessor/max_concurrent_processing_internal_test.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"errors"
 	"io"
+	"runtime"
 	"strings"
 	"sync"
 	"testing"
@@ -93,8 +94,7 @@ func processInBackground(
 	proc *ImageProcessor, reader *gatedReader, results chan<- error,
 ) {
 	go func() {
-		result, err := proc.Process(context.Background(), reader,
-			imagerequest.FormatJPEG, smallJPEGTransform())
+		result, err := proc.Process(context.Background(), reader, smallJPEGTransform())
 		if err == nil {
 			_ = result.Content.Close()
 		}
@@ -117,15 +117,47 @@ func waitForEntries(t *testing.T, entered <-chan struct{}, count int) {
 	}
 }
 
-func TestNewMakesMaxConcurrentProcessingSlots(t *testing.T) {
+func TestNewDefaultsMaxConcurrentProcessingToHalfTheCPUs(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 3})
+	for _, limit := range []int{0, -1} {
+		proc := New(Params{MaxConcurrentProcessing: limit})
+		if got := cap(proc.processingSemaphore); got != max(runtime.GOMAXPROCS(0)/2, 1) {
+			t.Errorf("MaxConcurrentProcessing %d: %d slots, want %d, half the CPUs",
+				limit, got, max(runtime.GOMAXPROCS(0)/2, 1))
+		}
+	}
+
+	proc := New(Params{MaxConcurrentProcessing: 3})
 	if got := cap(proc.processingSemaphore); got != 3 {
 		t.Errorf("MaxConcurrentProcessing 3: %d slots, want 3", got)
 	}
 }
 
+// TestNewDefaultIsHalfTheCPUsAndAtLeastOne checks that New, given no
+// MaxConcurrentProcessing, makes one slot for every two CPUs Go uses,
+// rounded down, and one slot when Go uses one CPU.
+//
+//nolint:paralleltest // it sets GOMAXPROCS, which other tests read
+func TestNewDefaultIsHalfTheCPUsAndAtLeastOne(t *testing.T) {
+	cpusBefore := runtime.GOMAXPROCS(0)
+
+	t.Cleanup(func() { runtime.GOMAXPROCS(cpusBefore) })
+
+	for _, tc := range []struct{ cpus, want int }{
+		{1, 1}, {2, 1}, {3, 1}, {8, 4},
+	} {
+		runtime.GOMAXPROCS(tc.cpus)
+
+		got := cap(New(Params{}).processingSemaphore)
+		t.Logf("GOMAXPROCS %d: %d slots", tc.cpus, got)
+
+		if got != tc.want {
+			t.Errorf("GOMAXPROCS %d: %d slots, want %d", tc.cpus, got, tc.want)
+		}
+	}
+}
+
 // TestProcessNeverExceedsMaxConcurrentProcessing starts more Process calls
 // than MaxConcurrentProcessing allows and holds the first ones inside
 // Process until the test lets them go. No more than the limit may be
@@ -139,7 +171,7 @@ func TestProcessNeverExceedsMaxConcurrentProcessing(t *testing.T) {
 		calls = 6
 	)
 
-	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: limit})
+	proc := New(Params{MaxConcurrentProcessing: limit})
 	input := createTestJPEG(t, 50, 50)
 
 	counter := &readingCounter{}
@@ -186,7 +218,7 @@ func TestProcessNeverExceedsMaxConcurrentProcessing(t *testing.T) {
 func TestProcessWaitsThenFailsWhenNoSlotFrees(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
+	proc := New(Params{MaxConcurrentProcessing: 1})
 	proc.processingWaitTimeout = 100 * time.Millisecond
 
 	input := createTestJPEG(t, 10, 10)
@@ -207,7 +239,7 @@ func TestProcessWaitsThenFailsWhenNoSlotFrees(t *testing.T) {
 	start := time.Now()
 
 	_, err := proc.Process(context.Background(), bytes.NewReader(input),
-		imagerequest.FormatJPEG, smallJPEGTransform())
+		smallJPEGTransform())
 	if !errors.Is(err, ErrTooManyImages) {
 		t.Fatalf("Process() error = %v, want ErrTooManyImages", err)
 	}
@@ -275,8 +307,7 @@ func TestProcessReleasesSlotOnError(t *testing.T) {
 			proc := New(Params{MaxInputBytes: 4096, MaxConcurrentProcessing: 1})
 			proc.processingWaitTimeout = 100 * time.Millisecond
 
-			_, err := proc.Process(context.Background(), tc.input,
-				imagerequest.FormatJPEG, tc.transform)
+			_, err := proc.Process(context.Background(), tc.input, tc.transform)
 			if err == nil || (tc.want != nil && !errors.Is(err, tc.want)) {
 				t.Fatalf("Process() error = %v, want %v", err, tc.want)
 			}
@@ -286,7 +317,7 @@ func TestProcessReleasesSlotOnError(t *testing.T) {
 			}
 
 			result, err := proc.Process(context.Background(), bytes.NewReader(valid),
-				imagerequest.FormatJPEG, smallJPEGTransform())
+				smallJPEGTransform())
 			if err != nil {
 				t.Fatalf("Process() after the error = %v, want nil", err)
 			}
@@ -303,7 +334,7 @@ func TestProcessReleasesSlotOnError(t *testing.T) {
 func TestWaitForProcessing(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 2})
+	proc := New(Params{MaxConcurrentProcessing: 2})
 
 	gate := make(chan struct{})
 	entered := make(chan struct{}, 1)

internal/imageprocessor/orig_format_internal_test.go

@@ -10,9 +10,8 @@ import (
 )
 
 // TestImageProcessor_OrigOfUnnamedFormatRefused verifies that orig of a TIFF
-// input is refused with ErrUnsupportedInputFormat before it is decoded, and
-// not saved as JPEG. TIFF is not a source format, and the test passes the
-// input to Process as a JPEG.
+// input, which is not a source format, is refused with
+// ErrUnsupportedInputFormat before it is decoded, and not saved as JPEG.
 func TestImageProcessor_OrigOfUnnamedFormatRefused(t *testing.T) {
 	t.Parallel()
 
@@ -28,11 +27,8 @@ func TestImageProcessor_OrigOfUnnamedFormatRefused(t *testing.T) {
 		t.Fatalf("failed to save test TIFF: %v", err)
 	}
 
-	result, err := New(Params{
-		MaxInputBytes:           50 << 20,
-		MaxConcurrentProcessing: 1,
-	}).Process(
-		t.Context(), bytes.NewReader(tiff), imagerequest.FormatJPEG,
+	result, err := New(Params{}).Process(
+		t.Context(), bytes.NewReader(tiff),
 		&imagerequest.Transform{Format: imagerequest.FormatOriginal},
 	)
 	if result != nil {

internal/imageprocessor/source_formats_internal_test.go

@@ -2,7 +2,6 @@ package imageprocessor
 
 import (
 	"bytes"
-	"errors"
 	"io"
 	"testing"
 
@@ -15,14 +14,14 @@ import (
 func TestImageProcessor_LoadsEachSourceFormat(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
+	proc := New(Params{})
 
 	for _, format := range []imagerequest.Format{
 		imagerequest.FormatJPEG, imagerequest.FormatPNG, imagerequest.FormatGIF,
 		imagerequest.FormatWebP, imagerequest.FormatAVIF, imagerequest.FormatJXL,
 	} {
 		saved, err := proc.Process(t.Context(),
-			bytes.NewReader(createTestPNG(t, 20, 20)), imagerequest.FormatPNG,
+			bytes.NewReader(createTestPNG(t, 20, 20)),
 			&imagerequest.Transform{Format: format})
 		if err != nil {
 			t.Fatalf("saving the test image as %s: %v", format, err)
@@ -33,7 +32,7 @@ func TestImageProcessor_LoadsEachSourceFormat(t *testing.T) {
 			t.Fatalf("reading the %s image: %v", format, err)
 		}
 
-		result, err := proc.Process(t.Context(), bytes.NewReader(source), format,
+		result, err := proc.Process(t.Context(), bytes.NewReader(source),
 			&imagerequest.Transform{Format: imagerequest.FormatOriginal})
 		if err != nil {
 			t.Errorf("orig of the %s image: %v", format, err)
@@ -43,33 +42,9 @@ func TestImageProcessor_LoadsEachSourceFormat(t *testing.T) {
 
 		t.Logf("orig of the %s image: %s", format, result.ContentType)
 
-		if result.ContentType != format.MIMEType() {
+		if result.ContentType != FormatToMIME(format) {
 			t.Errorf("orig of the %s image is %s, want %s",
-				format, result.ContentType, format.MIMEType())
-		}
-	}
-}
-
-// TestImageProcessor_NotASourceFormatRefused verifies that a source format
-// other than the six, such as orig, auto or none, is refused with
-// ErrUnsupportedInputFormat. The input is text, which libvips reads as no
-// format.
-func TestImageProcessor_NotASourceFormatRefused(t *testing.T) {
-	t.Parallel()
-
-	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
-
-	for _, sourceFormat := range []imagerequest.Format{
-		imagerequest.FormatOriginal, imagerequest.FormatAuto, "",
-	} {
-		result, err := proc.Process(t.Context(),
-			bytes.NewReader([]byte("this is text, not an image")), sourceFormat,
-			&imagerequest.Transform{Format: imagerequest.FormatJPEG})
-		t.Logf("source format %q: error = %v", sourceFormat, err)
-
-		if result != nil || !errors.Is(err, ErrUnsupportedInputFormat) {
-			t.Errorf("Process() with source format %q = %v, error %v; want %v",
-				sourceFormat, result, err, ErrUnsupportedInputFormat)
+				format, result.ContentType, FormatToMIME(format))
 		}
 	}
 }

internal/imageproxy/cache_hit_internal_test.go

@@ -1,100 +0,0 @@
-package imageproxy
-
-import (
-	"bytes"
-	"os"
-	"testing"
-	"time"
-
-	"sneak.berlin/go/pixa/internal/imagerequest"
-	"sneak.berlin/go/pixa/internal/imgcache"
-)
-
-// TestProxy_Get_MakesAgainVariantOfNoOutputFormat replaces a cached
-// variant's file with text, and checks that the next request is a miss
-// answered with the variant made again, and the one after a hit.
-func TestProxy_Get_MakesAgainVariantOfNoOutputFormat(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-	req := photoVariant(fixtures, 85, imagerequest.FitCover)
-
-	want, _ := getImage(t, svc, req)
-
-	path := variantFilePath(svc, imagerequest.CacheKey(req))
-
-	err := os.WriteFile(path, []byte("this is text, not an image"),
-		imgcache.StorageFilePerm)
-	if err != nil {
-		t.Fatalf("replacing the variant file: %v", err)
-	}
-
-	got, status := getImage(t, svc, req)
-	t.Logf("after the replacement: %d bytes, %s", len(got), status)
-
-	if status != CacheMiss || !bytes.Equal(got, want) {
-		t.Errorf("after the replacement: Get() = %d bytes, %s; want the %d bytes "+
-			"made again, %s", len(got), status, len(want), CacheMiss)
-	}
-
-	got, status = getImage(t, svc, req)
-
-	if status != CacheHit || !bytes.Equal(got, want) {
-		t.Errorf("next request: Get() = %d bytes, %s; want the %d bytes, %s",
-			len(got), status, len(want), CacheHit)
-	}
-}
-
-// TestProxy_Get_HitWaitsForNoDatabaseWrite holds the database's one
-// connection while a cached variant is requested. The hit must be answered
-// while the connection is still held, and its access time must reach the
-// database once it is free.
-func TestProxy_Get_HitWaitsForNoDatabaseWrite(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-	req := photoVariant(fixtures, 85, imagerequest.FitCover)
-	key := imagerequest.CacheKey(req)
-
-	getImage(t, svc, req)
-
-	// Each connection to an in-memory SQLite database opens a new, empty one,
-	// so the goroutine that writes the access times must share the
-	// connection that holds the schema.
-	svc.db.SetMaxOpenConns(1)
-	svc.cache.StartPendingAccessTimeWrites()
-
-	defer func() { _ = svc.cache.StopPendingAccessTimeWrites(t.Context()) }()
-
-	anHourAgo := time.Now().Add(-time.Hour)
-	setVariantLastAccessed(t, svc.db, key, anHourAgo)
-
-	releaseDatabase := holdDatabase(t, svc.db)
-	defer releaseDatabase()
-
-	results := startGet(t.Context(), svc, req)
-
-	select {
-	case got := <-results:
-		if got.err != nil {
-			t.Fatalf("Get() of the cached variant error = %v", got.err)
-		}
-	case <-time.After(pendingAccessTimesWait):
-		t.Fatal("the cache hit waited for the database")
-	}
-
-	releaseDatabase()
-
-	deadline := time.Now().Add(pendingAccessTimesWait)
-
-	for countRows(t, svc.db, `
-		SELECT COUNT(*) FROM variant_content
-		WHERE cache_key = ? AND last_accessed_at > ?
-	`, string(key), anHourAgo.UTC().Format(sqliteTimestampFormat)) == 0 {
-		if time.Now().After(deadline) {
-			t.Fatal("the hit's access time was not written")
-		}
-
-		time.Sleep(10 * time.Millisecond)
-	}
-}

internal/imageproxy/counters_internal_test.go

@@ -1,77 +0,0 @@
-package imageproxy
-
-import (
-	"errors"
-	"testing"
-
-	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/testutil"
-	"sneak.berlin/go/pixa/internal/imgcache"
-)
-
-// TestNew_RegistersItsCountersOnItsRegistry checks that New registers the
-// proxy's counters on the registry it is given, under the names README.md
-// gives them. The cache registers its own counters on another registry.
-func TestNew_RegistersItsCountersOnItsRegistry(t *testing.T) {
-	t.Parallel()
-
-	cache, err := imgcache.NewCache(setupTestDB(t),
-		imgcache.Config{StateDir: t.TempDir(), MaxBytes: 1 << 30},
-		prometheus.NewRegistry())
-	if err != nil {
-		t.Fatalf("imgcache.NewCache() error = %v", err)
-	}
-
-	registry := prometheus.NewRegistry()
-
-	_, err = New(&Config{Cache: cache}, registry)
-	if err != nil {
-		t.Fatalf("New() error = %v", err)
-	}
-
-	names := []string{
-		"pixa_upstream_fetches_total",
-		"pixa_upstream_fetch_bytes_total",
-		"pixa_transforms_total",
-	}
-
-	count, err := testutil.GatherAndCount(registry, names...)
-	if err != nil {
-		t.Fatalf("testutil.GatherAndCount() error = %v", err)
-	}
-
-	if count != len(names) {
-		t.Errorf("%d of the counters %v are on the registry, want %d",
-			count, names, len(names))
-	}
-}
-
-// TestNew_FailsWhenItsCountersCannotBeRegistered makes a second proxy on
-// the registry of a first. Its counters have the same names, so the
-// registry refuses them, and New must return that error.
-func TestNew_FailsWhenItsCountersCannotBeRegistered(t *testing.T) {
-	t.Parallel()
-
-	cache, err := imgcache.NewCache(setupTestDB(t),
-		imgcache.Config{StateDir: t.TempDir(), MaxBytes: 1 << 30},
-		prometheus.NewRegistry())
-	if err != nil {
-		t.Fatalf("imgcache.NewCache() error = %v", err)
-	}
-
-	registry := prometheus.NewRegistry()
-
-	_, err = New(&Config{Cache: cache}, registry)
-	if err != nil {
-		t.Fatalf("New() of the first proxy error = %v", err)
-	}
-
-	_, err = New(&Config{Cache: cache}, registry)
-	t.Logf("New() of the second proxy error = %v", err)
-
-	var alreadyRegistered prometheus.AlreadyRegisteredError
-	if !errors.As(err, &alreadyRegistered) {
-		t.Errorf("New() of the second proxy error = %v, want %T",
-			err, alreadyRegistered)
-	}
-}

internal/imageproxy/imageproxy_internal_test.go

@@ -1,575 +0,0 @@
-package imageproxy
-
-import (
-	"context"
-	"io"
-	"os"
-	"testing"
-	"time"
-
-	"sneak.berlin/go/pixa/internal/imagerequest"
-	"sneak.berlin/go/pixa/internal/magic"
-)
-
-// Test data literals used repeatedly in this file (goconst).
-const (
-	testPathPhoto  = "/images/photo.jpg"
-	testPathUpload = "/uploads/image.jpg"
-)
-
-func TestProxy_Get_GoodHost(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-	ctx := context.Background()
-
-	req := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 50},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	resp, err := svc.Get(ctx, req)
-	if err != nil {
-		t.Fatalf("Get() error = %v", err)
-	}
-
-	defer func() { _ = resp.Content.Close() }()
-
-	// Verify we got content
-	data, err := io.ReadAll(resp.Content)
-	if err != nil {
-		t.Fatalf("failed to read response: %v", err)
-	}
-
-	if len(data) == 0 {
-		t.Error("expected non-empty response")
-	}
-
-	if resp.ContentType != testContentTypeJPEG {
-		t.Errorf("ContentType = %q, want %q", resp.ContentType, testContentTypeJPEG)
-	}
-}
-
-// TestProxy_Get_OtherHost checks that the proxy serves a second host as it
-// serves GoodHost.
-func TestProxy_Get_OtherHost(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-	ctx := context.Background()
-
-	req := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.OtherHost,
-			Path: testPathUpload,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 50},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	// Should fetch successfully
-	resp, err := svc.Get(ctx, req)
-	if err != nil {
-		t.Fatalf("Get() error = %v", err)
-	}
-
-	defer func() { _ = resp.Content.Close() }()
-
-	data, err := io.ReadAll(resp.Content)
-	if err != nil {
-		t.Fatalf("failed to read response: %v", err)
-	}
-
-	if len(data) == 0 {
-		t.Error("expected non-empty response")
-	}
-}
-
-func TestProxy_Get_InvalidFile(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-	ctx := context.Background()
-
-	req := photoVariant(fixtures, 85, imagerequest.FitCover)
-	req.Source.Path = "/images/fake.jpg"
-	req.Transform.Size = imagerequest.Size{Width: 50, Height: 50}
-
-	// Should fail because magic bytes don't match
-	_, err := svc.Get(ctx, req)
-	if err == nil {
-		t.Error("Get() expected error for invalid file")
-	}
-}
-
-func TestProxy_Get_NotFound(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-	ctx := context.Background()
-
-	req := photoVariant(fixtures, 85, imagerequest.FitCover)
-	req.Source.Path = "/images/nonexistent.jpg"
-	req.Transform.Size = imagerequest.Size{Width: 50, Height: 50}
-
-	_, err := svc.Get(ctx, req)
-	if err == nil {
-		t.Error("Get() expected error for nonexistent file")
-	}
-}
-
-func TestProxy_Get_FormatConversion(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-	ctx := context.Background()
-
-	tests := []struct {
-		name       string
-		sourcePath string
-		outFormat  imagerequest.Format
-		wantMIME   string
-	}{
-		{
-			name:       "JPEG to PNG",
-			sourcePath: testPathPhoto,
-			outFormat:  imagerequest.FormatPNG,
-			wantMIME:   "image/png",
-		},
-		{
-			name:       "PNG to JPEG",
-			sourcePath: "/images/logo.png",
-			outFormat:  imagerequest.FormatJPEG,
-			wantMIME:   testContentTypeJPEG,
-		},
-		{
-			name:       "GIF to PNG",
-			sourcePath: "/images/animation.gif",
-			outFormat:  imagerequest.FormatPNG,
-			wantMIME:   "image/png",
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			t.Parallel()
-
-			req := &imagerequest.Request{
-				Source: imagerequest.Source{Host: fixtures.GoodHost, Path: tt.sourcePath},
-				Transform: imagerequest.Transform{
-					Size:   imagerequest.Size{Width: 50, Height: 50},
-					Format: tt.outFormat, Quality: 85, FitMode: imagerequest.FitCover,
-				},
-			}
-
-			resp, err := svc.Get(ctx, req)
-			if err != nil {
-				t.Fatalf("Get() error = %v", err)
-			}
-
-			defer func() { _ = resp.Content.Close() }()
-
-			if resp.ContentType != tt.wantMIME {
-				t.Errorf("ContentType = %q, want %q", resp.ContentType, tt.wantMIME)
-			}
-
-			// Verify magic bytes match the expected format
-			data, err := io.ReadAll(resp.Content)
-			if err != nil {
-				t.Fatalf("failed to read response: %v", err)
-			}
-
-			detectedFormat, err := magic.DetectFormat(data)
-			if err != nil {
-				t.Fatalf("failed to detect format: %v", err)
-			}
-
-			if detectedFormat.MIMEType() != tt.wantMIME {
-				t.Errorf("detected format = %q, want the format of %s",
-					detectedFormat, tt.wantMIME)
-			}
-		})
-	}
-}
-
-func TestProxy_Get_Caching(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-	ctx := context.Background()
-
-	req := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 50},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	// First request - should be a cache miss
-	resp1, err := svc.Get(ctx, req)
-	if err != nil {
-		t.Fatalf("Get() first request error = %v", err)
-	}
-
-	if resp1.CacheStatus != CacheMiss {
-		t.Errorf("first request CacheStatus = %q, want %q", resp1.CacheStatus, CacheMiss)
-	}
-
-	data1, err := io.ReadAll(resp1.Content)
-	if err != nil {
-		t.Fatalf("failed to read first response: %v", err)
-	}
-
-	_ = resp1.Content.Close()
-
-	// Second request - should be a cache hit
-	resp2, err := svc.Get(ctx, req)
-	if err != nil {
-		t.Fatalf("Get() second request error = %v", err)
-	}
-
-	if resp2.CacheStatus != CacheHit {
-		t.Errorf("second request CacheStatus = %q, want %q", resp2.CacheStatus, CacheHit)
-	}
-
-	data2, err := io.ReadAll(resp2.Content)
-	if err != nil {
-		t.Fatalf("failed to read second response: %v", err)
-	}
-
-	_ = resp2.Content.Close()
-
-	// Content should be identical
-	if len(data1) != len(data2) {
-		t.Errorf("response sizes differ: %d vs %d", len(data1), len(data2))
-	}
-}
-
-// TestProxy_Get_ServesSourceAndVariantCachedTwoDaysAgo caches a source and
-// a variant of it and sets back two days every time pixa stored for them.
-// For the source: last_accessed_at in source_content, and the access and
-// modification times of its file. For the variant: last_accessed_at in
-// variant_content, and the access and modification times of its file. It
-// then checks that the variant is still served from the cache and that a new
-// variant is made from the cached source without fetching it again.
-//
-// Left at the present: the files' status change and birth times, which a
-// program cannot set, and the times of the directories holding the files,
-// which other entries share.
-func TestProxy_Get_ServesSourceAndVariantCachedTwoDaysAgo(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-	variant := photoVariant(fixtures, 85, imagerequest.FitCover)
-
-	resp, err := svc.Get(t.Context(), variant)
-	if err != nil {
-		t.Fatalf("Get() first request error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	twoDaysAgo := time.Now().AddDate(0, 0, -2)
-	backdateSource(t, svc, variant, twoDaysAgo)
-	backdateVariant(t, svc, variant, twoDaysAgo)
-
-	resp, err = svc.Get(t.Context(), variant)
-	if err != nil {
-		t.Fatalf("Get() of the cached variant error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	if resp.CacheStatus != CacheHit {
-		t.Errorf("cached variant CacheStatus = %q, want %q",
-			resp.CacheStatus, CacheHit)
-	}
-
-	// Another quality is a new variant, made from the cached source
-	resp, err = svc.Get(t.Context(), photoVariant(fixtures, 40, imagerequest.FitCover))
-	if err != nil {
-		t.Fatalf("Get() of a new variant error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	fetches := readCounters(t, svc).upstreamFetchCount
-	if fetches != 1 {
-		t.Errorf("upstream fetches = %d, want 1", fetches)
-	}
-}
-
-// backdateSource sets every time pixa stored for req's cached source to when,
-// as listed on TestProxy_Get_ServesSourceAndVariantCachedTwoDaysAgo.
-func backdateSource(
-	t *testing.T, svc *testProxy, req *imagerequest.Request, when time.Time,
-) {
-	t.Helper()
-
-	key := req.Source.Key()
-	setSourceLastAccessed(t, svc.db, key, when)
-
-	path := sourceFilePath(svc, key)
-
-	err := os.Chtimes(path, when, when)
-	if err != nil {
-		t.Fatalf("setting back the times of %s: %v", path, err)
-	}
-}
-
-// backdateVariant sets every time pixa stored for the cached variant req asks
-// for to when, as listed on
-// TestProxy_Get_ServesSourceAndVariantCachedTwoDaysAgo.
-func backdateVariant(
-	t *testing.T, svc *testProxy, req *imagerequest.Request, when time.Time,
-) {
-	t.Helper()
-
-	key := imagerequest.CacheKey(req)
-	path := variantFilePath(svc, key)
-
-	setVariantLastAccessed(t, svc.db, key, when)
-
-	err := os.Chtimes(path, when, when)
-	if err != nil {
-		t.Fatalf("setting back the times of %s: %v", path, err)
-	}
-}
-
-func TestProxy_Get_DifferentSizes(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-	ctx := context.Background()
-
-	// Request same image at different sizes
-	sizes := []imagerequest.Size{
-		{Width: 25, Height: 25},
-		{Width: 50, Height: 50},
-		{Width: 75, Height: 75},
-	}
-
-	responses := make([][]byte, 0, len(sizes))
-
-	for _, size := range sizes {
-		req := &imagerequest.Request{
-			Source: imagerequest.Source{
-				Host: fixtures.GoodHost,
-				Path: testPathPhoto,
-			},
-			Transform: imagerequest.Transform{
-				Size:    size,
-				Format:  imagerequest.FormatJPEG,
-				Quality: 85,
-				FitMode: imagerequest.FitCover,
-			},
-		}
-
-		resp, err := svc.Get(ctx, req)
-		if err != nil {
-			t.Fatalf("Get() error for size %v = %v", size, err)
-		}
-
-		data, err := io.ReadAll(resp.Content)
-		if err != nil {
-			t.Fatalf("failed to read response: %v", err)
-		}
-
-		_ = resp.Content.Close()
-
-		responses = append(responses, data)
-	}
-
-	// All responses should be different sizes (different cache entries)
-	for i := range len(responses) - 1 {
-		if len(responses[i]) == len(responses[i+1]) {
-			// Not necessarily an error, but worth noting
-			t.Logf("responses %d and %d have same size: %d bytes",
-				i, i+1, len(responses[i]))
-		}
-	}
-}
-
-func TestProxy_Get_ContextCancellation(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-
-	ctx, cancel := context.WithCancel(context.Background())
-	cancel() // Cancel immediately
-
-	req := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 50},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	_, err := svc.Get(ctx, req)
-	if err == nil {
-		t.Error("Get() expected error for cancelled context")
-	}
-}
-
-func TestProxy_Get_ReturnsETag(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-	ctx := context.Background()
-
-	req := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 50},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	resp, err := svc.Get(ctx, req)
-	if err != nil {
-		t.Fatalf("Get() error = %v", err)
-	}
-
-	defer func() { _ = resp.Content.Close() }()
-
-	// ETag should be set
-	if resp.ETag == "" {
-		t.Error("ETag should be set in response")
-	}
-
-	// ETag should be properly quoted
-	if len(resp.ETag) < 2 || resp.ETag[0] != '"' || resp.ETag[len(resp.ETag)-1] != '"' {
-		t.Errorf("ETag should be quoted, got %q", resp.ETag)
-	}
-}
-
-func TestProxy_Get_ETagConsistency(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-	ctx := context.Background()
-
-	req := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 50},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	// First request
-	resp1, err := svc.Get(ctx, req)
-	if err != nil {
-		t.Fatalf("Get() first request error = %v", err)
-	}
-
-	etag1 := resp1.ETag
-
-	_ = resp1.Content.Close()
-
-	// Second request (from cache)
-	resp2, err := svc.Get(ctx, req)
-	if err != nil {
-		t.Fatalf("Get() second request error = %v", err)
-	}
-
-	etag2 := resp2.ETag
-
-	_ = resp2.Content.Close()
-
-	// ETags should be identical for the same content
-	if etag1 != etag2 {
-		t.Errorf("ETags should match: %q != %q", etag1, etag2)
-	}
-}
-
-func TestProxy_Get_DifferentETagsForDifferentContent(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-	ctx := context.Background()
-
-	// Request same image at different sizes - should get different ETags
-	req1 := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 25, Height: 25},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	req2 := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 50},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	resp1, err := svc.Get(ctx, req1)
-	if err != nil {
-		t.Fatalf("Get() first request error = %v", err)
-	}
-
-	etag1 := resp1.ETag
-
-	_ = resp1.Content.Close()
-
-	resp2, err := svc.Get(ctx, req2)
-	if err != nil {
-		t.Fatalf("Get() second request error = %v", err)
-	}
-
-	etag2 := resp2.ETag
-
-	_ = resp2.Content.Close()
-
-	// ETags should be different for different content
-	if etag1 == etag2 {
-		t.Error("ETags should differ for different sizes")
-	}
-}

internal/imageproxy/negative_cache_internal_test.go

@@ -1,96 +0,0 @@
-package imageproxy
-
-import (
-	"errors"
-	"os"
-	"testing"
-
-	"sneak.berlin/go/pixa/internal/imagerequest"
-)
-
-// TestProxy_Get_ServesCachedVariantOfNegativeCachedURL caches a variant of
-// the test photo, then keeps a failed fetch of the photo's URL in the negative
-// cache, as a failed fetch for another variant does once the source has been
-// evicted. The cached variant is still served, and a variant not in the cache
-// is made from the cached source. Once the source is evicted, a variant not in
-// the cache needs a fetch and is refused.
-func TestProxy_Get_ServesCachedVariantOfNegativeCachedURL(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-
-	resp, err := svc.Get(t.Context(), photoVariant(fixtures, 85, imagerequest.FitCover))
-	if err != nil {
-		t.Fatalf("Get() first request error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	err = svc.cache.PutFailure(t.Context(),
-		photoVariant(fixtures, 85, imagerequest.FitCover).Source)
-	if err != nil {
-		t.Fatalf("PutFailure() error = %v", err)
-	}
-
-	resp, err = svc.Get(t.Context(), photoVariant(fixtures, 85, imagerequest.FitCover))
-	if err != nil {
-		t.Fatalf("Get() of the cached variant error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	if resp.CacheStatus != CacheHit {
-		t.Errorf("cached variant CacheStatus = %q, want %q",
-			resp.CacheStatus, CacheHit)
-	}
-
-	resp, err = svc.Get(t.Context(), photoVariant(fixtures, 40, imagerequest.FitCover))
-	t.Logf("Get() of a variant made from the cached source: error = %v", err)
-
-	if err != nil {
-		t.Fatalf("Get() of a variant made from the cached source error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	source := photoVariant(fixtures, 85, imagerequest.FitCover).Source
-
-	reader, _, _, err := svc.cache.Source(t.Context(), source)
-	if err != nil {
-		t.Fatalf("Source() error = %v, want the cached source", err)
-	}
-
-	_ = reader.Close()
-
-	// Evicts the source as the cache's eviction does: its row, then its file
-	_, err = svc.db.ExecContext(t.Context(),
-		`DELETE FROM source_content WHERE source_key = ?`, string(source.Key()))
-	if err != nil {
-		t.Fatalf("deleting the source's row: %v", err)
-	}
-
-	err = os.Remove(sourceFilePath(svc, source.Key()))
-	if err != nil {
-		t.Fatalf("removing the source's file: %v", err)
-	}
-
-	_, err = svc.Get(t.Context(), photoVariant(fixtures, 60, imagerequest.FitCover))
-	t.Logf("Get() of a variant whose source was evicted: error = %v", err)
-
-	if !errors.Is(err, ErrNegativeCached) {
-		t.Errorf("Get() of a variant whose source was evicted error = %v, want %v",
-			err, ErrNegativeCached)
-	}
-}
-
-func TestProxy_Get_ReturnsErrorForNegativeCachedURL(t *testing.T) {
-	t.Parallel()
-
-	// This test verifies that Proxy.Get() checks the negative cache
-	// We can't easily test the full pipeline without vips, but we can
-	// verify the error type
-	err := ErrNegativeCached
-	if !errors.Is(err, ErrNegativeCached) {
-		t.Error("ErrNegativeCached should be identifiable with errors.Is")
-	}
-}

internal/imageproxy/partial_cache_files_internal_test.go

@@ -1,184 +0,0 @@
-package imageproxy
-
-import (
-	"bytes"
-	"io"
-	"os"
-	"testing"
-
-	"sneak.berlin/go/pixa/internal/imagerequest"
-	"sneak.berlin/go/pixa/internal/imgcache"
-)
-
-// getImage calls Get for req and returns the image it answered with and
-// its cache status.
-func getImage(
-	t *testing.T, svc *testProxy, req *imagerequest.Request,
-) ([]byte, CacheStatus) {
-	t.Helper()
-
-	resp, err := svc.Get(t.Context(), req)
-	if err != nil {
-		t.Fatalf("Get() of quality %d error = %v", req.Transform.Quality, err)
-	}
-
-	defer func() { _ = resp.Content.Close() }()
-
-	body, err := io.ReadAll(resp.Content)
-	if err != nil {
-		t.Fatalf("reading the image of quality %d: %v", req.Transform.Quality, err)
-	}
-
-	return body, resp.CacheStatus
-}
-
-// fileSize returns the size of the file at path.
-func fileSize(t *testing.T, path string) int64 {
-	t.Helper()
-
-	info, err := os.Stat(path)
-	if err != nil {
-		t.Fatalf("stat %s: %v", path, err)
-	}
-
-	return info.Size()
-}
-
-// cachedSourcePath returns the path of the cached source file req uses.
-func cachedSourcePath(
-	t *testing.T, svc *testProxy, req *imagerequest.Request,
-) string {
-	t.Helper()
-
-	reader, _, _, err := svc.cache.Source(t.Context(), req.Source)
-	if err != nil {
-		t.Fatalf("Source() error = %v; want the cached source", err)
-	}
-
-	_ = reader.Close()
-
-	return sourceFilePath(svc, req.Source.Key())
-}
-
-// TestProxy_Get_FetchesAgainForRemovedCachedSource removes the cached
-// source's row and file, as the reconciliation pass does when the file is
-// empty or cut short. internal/imgcache tests that the pass does so. The
-// test then asks for two new sizes of the source. The first must fetch it
-// again and cache it whole, so the second is made from the cache without a
-// third fetch.
-func TestProxy_Get_FetchesAgainForRemovedCachedSource(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-
-	getImage(t, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-
-	source := photoVariant(fixtures, 85, imagerequest.FitCover).Source
-	path := cachedSourcePath(t, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-	wholeSize := fileSize(t, path)
-
-	// Removes the source as the reconciliation pass does: its row, then its file
-	_, err := svc.db.ExecContext(t.Context(),
-		`DELETE FROM source_content WHERE source_key = ?`, string(source.Key()))
-	if err != nil {
-		t.Fatalf("deleting the source's row: %v", err)
-	}
-
-	err = os.Remove(path)
-	if err != nil {
-		t.Fatalf("removing the source's file: %v", err)
-	}
-
-	getImage(t, svc, photoVariant(fixtures, 40, imagerequest.FitCover))
-	getImage(t, svc, photoVariant(fixtures, 30, imagerequest.FitCover))
-
-	fetches := readCounters(t, svc).upstreamFetchCount
-	t.Logf("upstream fetches = %d", fetches)
-
-	if fetches != 2 {
-		t.Errorf("upstream fetches = %d, want 2", fetches)
-	}
-
-	size := fileSize(t, path)
-	if size != wholeSize {
-		t.Errorf("cached source is %d bytes, want %d", size, wholeSize)
-	}
-}
-
-// TestProxy_Get_FetchesAgainSourceOfNoSourceFormat replaces the cached
-// source's file with text. The next request for a new size of the source
-// must fetch it again and cache it whole.
-func TestProxy_Get_FetchesAgainSourceOfNoSourceFormat(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-
-	getImage(t, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-
-	path := cachedSourcePath(t, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-	wholeSize := fileSize(t, path)
-
-	err := os.WriteFile(path, []byte("this is text, not an image"),
-		imgcache.StorageFilePerm)
-	if err != nil {
-		t.Fatalf("replacing the source's file: %v", err)
-	}
-
-	getImage(t, svc, photoVariant(fixtures, 40, imagerequest.FitCover))
-
-	fetches := readCounters(t, svc).upstreamFetchCount
-	t.Logf("upstream fetches = %d", fetches)
-
-	if fetches != 2 {
-		t.Errorf("upstream fetches = %d, want 2", fetches)
-	}
-
-	size := fileSize(t, path)
-	if size != wholeSize {
-		t.Errorf("cached source is %d bytes, want %d", size, wholeSize)
-	}
-}
-
-// TestProxy_Get_ConvertsAgainForRemovedCachedVariant caches a variant of
-// the photo and removes its row and file, as the reconciliation pass does
-// when the file is empty or cut short. internal/imgcache tests that the
-// pass does so. The test then checks that Get converts the image again, and
-// that the next Get serves the whole variant from the cache.
-func TestProxy_Get_ConvertsAgainForRemovedCachedVariant(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-	req := photoVariant(fixtures, 85, imagerequest.FitCover)
-
-	want, _ := getImage(t, svc, req)
-
-	key := imagerequest.CacheKey(req)
-
-	// Removes the variant as the reconciliation pass does: its row, then its file
-	_, err := svc.db.ExecContext(t.Context(),
-		`DELETE FROM variant_content WHERE cache_key = ?`, string(key))
-	if err != nil {
-		t.Fatalf("deleting the variant's row: %v", err)
-	}
-
-	err = os.Remove(variantFilePath(svc, key))
-	if err != nil {
-		t.Fatalf("removing the variant's file: %v", err)
-	}
-
-	got, status := getImage(t, svc, req)
-	t.Logf("after the removal: %d bytes, %s", len(got), status)
-
-	if status != CacheMiss || !bytes.Equal(got, want) {
-		t.Errorf("after the removal: Get() = %d bytes, %s; want the %d bytes "+
-			"converted again, %s", len(got), status, len(want), CacheMiss)
-	}
-
-	got, status = getImage(t, svc, req)
-	t.Logf("next request: %d bytes, %s", len(got), status)
-
-	if status != CacheHit || !bytes.Equal(got, want) {
-		t.Errorf("next request: Get() = %d bytes, %s; want the %d bytes, %s",
-			len(got), status, len(want), CacheHit)
-	}
-}

internal/imageproxy/pendingaccesstimes_internal_test.go

@@ -1,78 +0,0 @@
-package imageproxy
-
-import (
-	"context"
-	"database/sql"
-	"errors"
-	"testing"
-	"time"
-
-	"sneak.berlin/go/pixa/internal/imagerequest"
-)
-
-// pendingAccessTimesWait is how long a test waits for the database's
-// connection, for a cache hit to be answered, for an access time to reach
-// the database, or for a request to return past its deadline.
-const pendingAccessTimesWait = 5 * time.Second
-
-// holdDatabase takes the one connection of db, so that every other query
-// waits for it, and returns the func that frees it.
-func holdDatabase(t *testing.T, db *sql.DB) func() {
-	t.Helper()
-
-	ctx, cancel := context.WithTimeout(t.Context(), pendingAccessTimesWait)
-	defer cancel()
-
-	conn, err := db.Conn(ctx)
-	if err != nil {
-		t.Fatalf("failed to take the database connection: %v", err)
-	}
-
-	return func() { _ = conn.Close() }
-}
-
-// TestProxy_Get_ReturnsByItsDeadlineWhileTheDatabaseIsBusy holds the
-// database's one connection while a request whose fetch is held reaches its
-// deadline. The request must return with the deadline's error while the
-// connection is still held, as it waits for no database write past its
-// deadline.
-func TestProxy_Get_ReturnsByItsDeadlineWhileTheDatabaseIsBusy(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures, fetcher := setupHeldFetchProxy(t)
-
-	svc.cache.StartPendingAccessTimeWrites()
-	defer func() { _ = svc.cache.StopPendingAccessTimeWrites(t.Context()) }()
-
-	// Room for the request to reach its fetch on a busy host
-	const timeout = 2 * time.Second
-
-	ctx, cancel := context.WithTimeout(t.Context(), timeout)
-	defer cancel()
-
-	deadline, _ := ctx.Deadline()
-
-	results := startGet(ctx, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-
-	// The request has made its database reads by the time it fetches.
-	select {
-	case <-fetcher.started:
-	case <-time.After(timeout):
-		t.Fatal("request did not reach its fetch by its deadline")
-	}
-
-	releaseDatabase := holdDatabase(t, svc.db)
-	defer releaseDatabase()
-
-	select {
-	case got := <-results:
-		t.Logf("Get() returned %v after its deadline, error = %v",
-			time.Since(deadline), got.err)
-
-		if !errors.Is(got.err, context.DeadlineExceeded) {
-			t.Errorf("Get() error = %v, want %v", got.err, context.DeadlineExceeded)
-		}
-	case <-time.After(time.Until(deadline) + pendingAccessTimesWait):
-		t.Fatal("request did not return while the database was busy")
-	}
-}

internal/imageproxy/stats_internal_test.go

@@ -1,245 +0,0 @@
-package imageproxy
-
-import (
-	"bytes"
-	"context"
-	"image/color"
-	"io"
-	"io/fs"
-	"testing"
-
-	"sneak.berlin/go/pixa/internal/httpfetcher"
-	"sneak.berlin/go/pixa/internal/imagerequest"
-)
-
-// TestProxy_Get_CountsStats walks Get through a miss that fetches the
-// source, a hit, a miss that reuses the cached source, and two misses whose
-// source cannot be used, checking every counter of the proxy and its cache
-// after each.
-func TestProxy_Get_CountsStats(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-
-	// NewTestFS builds the same files the test proxy's fetcher serves.
-	testFS, _ := NewTestFS(t)
-
-	photo, err := fs.ReadFile(testFS, fixtures.GoodHostJPEG)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	fake, err := fs.ReadFile(testFS, fixtures.InvalidFile)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	photoBytes, fakeBytes := int64(len(photo)), int64(len(fake))
-
-	// want is hits, misses, upstream fetches, upstream bytes, transforms.
-	steps := []struct {
-		name    string
-		path    string
-		size    int
-		wantErr bool
-		want    counterValues
-	}{
-		{"miss that fetches the source", testPathPhoto, 50, false,
-			counterValues{0, 1, 1, photoBytes, 1}},
-		{"hit", testPathPhoto, 50, false,
-			counterValues{1, 1, 1, photoBytes, 1}},
-		{"miss that reuses the cached source", testPathPhoto, 25, false,
-			counterValues{1, 2, 1, photoBytes, 2}},
-		{"miss whose source fails the magic byte check", "/images/fake.jpg", 50, true,
-			counterValues{1, 3, 2, photoBytes + fakeBytes, 2}},
-		{"miss whose source is not found", "/images/nonexistent.jpg", 50, true,
-			counterValues{1, 4, 2, photoBytes + fakeBytes, 2}},
-	}
-
-	for _, step := range steps {
-		resp, err := svc.Get(t.Context(), &imagerequest.Request{
-			Source: imagerequest.Source{
-				Host: fixtures.GoodHost,
-				Path: step.path,
-			},
-			Transform: imagerequest.Transform{
-				Size:    imagerequest.Size{Width: step.size, Height: step.size},
-				Format:  imagerequest.FormatJPEG,
-				Quality: 85,
-				FitMode: imagerequest.FitCover,
-			},
-		})
-		if (err != nil) != step.wantErr {
-			t.Fatalf("%s: Get() error = %v, want error %t", step.name, err, step.wantErr)
-		}
-
-		if err == nil {
-			_ = resp.Content.Close()
-		}
-
-		got := readCounters(t, svc)
-		if got != step.want {
-			t.Fatalf("after the %s: counters = %+v, want %+v", step.name, got, step.want)
-		}
-	}
-}
-
-// fakeUpstream answers every fetch with itself as a JPEG body. The body
-// serves data, then calls cancel, when set, and returns err; io.EOF ends
-// the body normally.
-type fakeUpstream struct {
-	data   *bytes.Reader
-	cancel context.CancelFunc
-	err    error
-}
-
-func (u *fakeUpstream) Fetch(
-	context.Context, imagerequest.Source,
-) (*httpfetcher.FetchResult, error) {
-	return &httpfetcher.FetchResult{
-		Content:       io.NopCloser(u),
-		ContentLength: -1,
-		ContentType:   testContentTypeJPEG,
-	}, nil
-}
-
-func (u *fakeUpstream) Read(p []byte) (int, error) {
-	if u.data.Len() > 0 {
-		return u.data.Read(p)
-	}
-
-	if u.cancel != nil {
-		u.cancel()
-	}
-
-	return 0, u.err
-}
-
-// TestProxy_Get_CountsInterruptedMisses checks every counter of the proxy
-// and its cache after a miss whose request context ends during or after the
-// upstream fetch, and after a miss whose upstream body is over the size
-// limit.
-func TestProxy_Get_CountsInterruptedMisses(t *testing.T) {
-	t.Parallel()
-
-	photo := generateTestJPEG(t, 100, 100, color.RGBA{255, 0, 0, 255})
-	half := len(photo) / 2
-
-	// want is hits, misses, upstream fetches, upstream bytes, transforms.
-	tests := []struct {
-		name    string
-		served  int   // bytes of the photo the upstream body serves
-		cancel  bool  // whether the body then ends the request context
-		readErr error // what the body then returns
-		wantErr bool
-		want    counterValues
-	}{
-		{"request context ends during the fetch", half, true, context.Canceled, true,
-			counterValues{0, 1, 1, int64(half), 0}},
-		{"request context ends after the fetch", len(photo), true, io.EOF, false,
-			counterValues{0, 1, 1, int64(len(photo)), 1}},
-		{"upstream body over the size limit", half, false,
-			httpfetcher.ErrResponseTooLarge, true,
-			counterValues{0, 1, 1, int64(half), 0}},
-	}
-
-	for _, tc := range tests {
-		t.Run(tc.name, func(t *testing.T) {
-			t.Parallel()
-
-			svc, fixtures := setupTestProxy(t)
-
-			ctx, cancel := context.WithCancel(t.Context())
-			defer cancel()
-
-			upstream := &fakeUpstream{
-				data: bytes.NewReader(photo[:tc.served]),
-				err:  tc.readErr,
-			}
-			if tc.cancel {
-				upstream.cancel = cancel
-			}
-
-			svc.fetcher = upstream
-
-			resp, err := svc.Get(ctx, &imagerequest.Request{
-				Source: imagerequest.Source{
-					Host: fixtures.GoodHost,
-					Path: testPathPhoto,
-				},
-				Transform: imagerequest.Transform{
-					Size:    imagerequest.Size{Width: 50, Height: 50},
-					Format:  imagerequest.FormatJPEG,
-					Quality: 85,
-					FitMode: imagerequest.FitCover,
-				},
-			})
-			t.Logf("Get() error = %v", err)
-
-			if (err != nil) != tc.wantErr {
-				t.Fatalf("Get() error = %v, want error %t", err, tc.wantErr)
-			}
-
-			if err == nil {
-				_ = resp.Content.Close()
-			}
-
-			got := readCounters(t, svc)
-			if got != tc.want {
-				t.Errorf("counters = %+v, want %+v", got, tc.want)
-			}
-		})
-	}
-}
-
-// TestProxy_Get_CountsHitAfterRequestEnds checks every counter of the
-// proxy and its cache after a hit served with a request context that has
-// already ended: only the hit count moves.
-func TestProxy_Get_CountsHitAfterRequestEnds(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := setupTestProxy(t)
-
-	req := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 50},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	// A first request caches the variant.
-	resp, err := svc.Get(t.Context(), req)
-	if err != nil {
-		t.Fatalf("first Get() error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	want := readCounters(t, svc)
-	want.hitCount++
-
-	ctx, cancel := context.WithCancel(t.Context())
-	cancel()
-
-	resp, err = svc.Get(ctx, req)
-	if err != nil {
-		t.Fatalf("Get() with an ended request context: error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	if resp.CacheStatus != CacheHit {
-		t.Fatalf("CacheStatus = %v, want %v", resp.CacheStatus, CacheHit)
-	}
-
-	got := readCounters(t, svc)
-	if got != want {
-		t.Errorf("counters = %+v, want %+v", got, want)
-	}
-}

internal/imageproxy/testutil_internal_test.go

@@ -1,355 +0,0 @@
-package imageproxy
-
-import (
-	"bytes"
-	"context"
-	"database/sql"
-	"image"
-	"image/color"
-	"image/gif"
-	"image/jpeg"
-	"image/png"
-	"io/fs"
-	"path/filepath"
-	"testing"
-	"testing/fstest"
-	"time"
-
-	"github.com/prometheus/client_golang/prometheus"
-	"sneak.berlin/go/pixa/internal/database"
-	"sneak.berlin/go/pixa/internal/httpfetcher"
-	"sneak.berlin/go/pixa/internal/imageprocessor"
-	"sneak.berlin/go/pixa/internal/imagerequest"
-	"sneak.berlin/go/pixa/internal/imgcache"
-)
-
-// Shared test data literals, extracted as constants for goconst.
-const (
-	testContentTypeJPEG = "image/jpeg"
-)
-
-// sqliteTimestampFormat matches the format SQLite's CURRENT_TIMESTAMP
-// produces, so injected timestamps compare correctly against ones the
-// cache writes.
-const sqliteTimestampFormat = "2006-01-02 15:04:05"
-
-// TestFixtures contains paths to test files in the mock filesystem.
-type TestFixtures struct {
-	// Valid image files
-	GoodHostJPEG  string // valid JPEG on GoodHost
-	GoodHostPNG   string // valid PNG on GoodHost
-	GoodHostGIF   string // valid GIF on GoodHost
-	OtherHostJPEG string // valid JPEG on OtherHost
-	OtherHostPNG  string // valid PNG on OtherHost
-
-	// Invalid/edge case files
-	InvalidFile string // file with wrong magic bytes
-	EmptyFile   string // zero-byte file
-	TextFile    string // text file masquerading as image
-
-	// Hostnames
-	GoodHost  string // a host the mock fetcher serves
-	OtherHost string // a second host the mock fetcher serves
-}
-
-// DefaultFixtures returns the standard test fixture paths.
-func DefaultFixtures() *TestFixtures {
-	return &TestFixtures{
-		GoodHostJPEG:  "goodhost.example.com/images/photo.jpg",
-		GoodHostPNG:   "goodhost.example.com/images/logo.png",
-		GoodHostGIF:   "goodhost.example.com/images/animation.gif",
-		OtherHostJPEG: "otherhost.example.com/uploads/image.jpg",
-		OtherHostPNG:  "otherhost.example.com/uploads/icon.png",
-		InvalidFile:   "goodhost.example.com/images/fake.jpg",
-		EmptyFile:     "goodhost.example.com/images/empty.jpg",
-		TextFile:      "goodhost.example.com/images/text.png",
-		GoodHost:      "goodhost.example.com",
-		OtherHost:     "otherhost.example.com",
-	}
-}
-
-// NewTestFS creates a mock filesystem with test images.
-func NewTestFS(t *testing.T) (fs.FS, *TestFixtures) {
-	t.Helper()
-
-	fixtures := DefaultFixtures()
-
-	// Generate test images
-	jpegData := generateTestJPEG(t, 100, 100, color.RGBA{255, 0, 0, 255})
-	pngData := generateTestPNG(t, 100, 100, color.RGBA{0, 255, 0, 255})
-	gifData := generateTestGIF(t, 100, 100, color.RGBA{0, 0, 255, 255})
-
-	// Create the mock filesystem
-	mockFS := fstest.MapFS{
-		// Good host files
-		fixtures.GoodHostJPEG: &fstest.MapFile{Data: jpegData},
-		fixtures.GoodHostPNG:  &fstest.MapFile{Data: pngData},
-		fixtures.GoodHostGIF:  &fstest.MapFile{Data: gifData},
-
-		// Other host files
-		fixtures.OtherHostJPEG: &fstest.MapFile{Data: jpegData},
-		fixtures.OtherHostPNG:  &fstest.MapFile{Data: pngData},
-
-		// Invalid files
-		fixtures.InvalidFile: &fstest.MapFile{Data: []byte("not a real image file content")},
-		fixtures.EmptyFile:   &fstest.MapFile{Data: []byte{}},
-		fixtures.TextFile:    &fstest.MapFile{Data: []byte("This is just text, not a PNG")},
-	}
-
-	return mockFS, fixtures
-}
-
-// generateTestJPEG creates a minimal valid JPEG image.
-func generateTestJPEG(t *testing.T, width, height int, c color.Color) []byte {
-	t.Helper()
-
-	img := image.NewRGBA(image.Rect(0, 0, width, height))
-	for y := range height {
-		for x := range width {
-			img.Set(x, y, c)
-		}
-	}
-
-	var buf bytes.Buffer
-
-	err := jpeg.Encode(&buf, img, &jpeg.Options{Quality: 85})
-	if err != nil {
-		t.Fatalf("failed to encode test JPEG: %v", err)
-	}
-
-	return buf.Bytes()
-}
-
-// generateTestPNG creates a minimal valid PNG image.
-func generateTestPNG(t *testing.T, width, height int, c color.Color) []byte {
-	t.Helper()
-
-	img := image.NewRGBA(image.Rect(0, 0, width, height))
-	for y := range height {
-		for x := range width {
-			img.Set(x, y, c)
-		}
-	}
-
-	var buf bytes.Buffer
-
-	err := png.Encode(&buf, img)
-	if err != nil {
-		t.Fatalf("failed to encode test PNG: %v", err)
-	}
-
-	return buf.Bytes()
-}
-
-// generateTestGIF creates a minimal valid GIF image.
-func generateTestGIF(t *testing.T, width, height int, c color.Color) []byte {
-	t.Helper()
-
-	img := image.NewPaletted(
-		image.Rect(0, 0, width, height),
-		[]color.Color{c, color.White},
-	)
-	for y := range height {
-		for x := range width {
-			img.SetColorIndex(x, y, 0)
-		}
-	}
-
-	var buf bytes.Buffer
-
-	err := gif.Encode(&buf, img, nil)
-	if err != nil {
-		t.Fatalf("failed to encode test GIF: %v", err)
-	}
-
-	return buf.Bytes()
-}
-
-// testProxy is a Proxy with the database and the state directory of its
-// cache, through which a test reads and changes the cache behind the proxy.
-// registry is the metrics registry the proxy and its cache share.
-type testProxy struct {
-	*Proxy
-
-	db       *sql.DB
-	stateDir string
-	registry *prometheus.Registry
-}
-
-// setupTestProxy creates a Proxy with mock fetcher for testing.
-func setupTestProxy(t *testing.T) (*testProxy, *TestFixtures) {
-	t.Helper()
-
-	mockFS, fixtures := NewTestFS(t)
-
-	// Create temp directory for cache
-	tmpDir := t.TempDir()
-
-	// Create in-memory database
-	db := setupTestDB(t)
-
-	registry := prometheus.NewRegistry()
-
-	cache, err := imgcache.NewCache(db, imgcache.Config{
-		StateDir:    tmpDir,
-		NegativeTTL: 5 * time.Minute,
-		MaxBytes:    1 << 30,
-	}, registry)
-	if err != nil {
-		t.Fatalf("failed to create cache: %v", err)
-	}
-
-	proxy, err := New(&Config{
-		Cache:   cache,
-		Fetcher: httpfetcher.NewMock(mockFS),
-		Processor: imageprocessor.New(imageprocessor.Params{
-			MaxInputBytes:           50 << 20,
-			MaxConcurrentProcessing: 2,
-		}),
-		MaxResponseSize: 50 << 20,
-	}, registry)
-	if err != nil {
-		t.Fatalf("failed to create proxy: %v", err)
-	}
-
-	return &testProxy{
-		Proxy:    proxy,
-		db:       db,
-		stateDir: tmpDir,
-		registry: registry,
-	}, fixtures
-}
-
-// counterValues holds the values of the counters of a proxy and its cache.
-type counterValues struct {
-	hitCount           int64
-	missCount          int64
-	upstreamFetchCount int64
-	upstreamFetchBytes int64
-	transformCount     int64
-}
-
-// readCounters reads the counters of svc and its cache from their metrics
-// registry.
-func readCounters(t *testing.T, svc *testProxy) counterValues {
-	t.Helper()
-
-	families, err := svc.registry.Gather()
-	if err != nil {
-		t.Fatalf("failed to gather the counters: %v", err)
-	}
-
-	values := make(map[string]int64, len(families))
-
-	for _, family := range families {
-		values[family.GetName()] = int64(family.GetMetric()[0].GetCounter().GetValue())
-	}
-
-	return counterValues{
-		hitCount:           values["pixa_cache_hits_total"],
-		missCount:          values["pixa_cache_misses_total"],
-		upstreamFetchCount: values["pixa_upstream_fetches_total"],
-		upstreamFetchBytes: values["pixa_upstream_fetch_bytes_total"],
-		transformCount:     values["pixa_transforms_total"],
-	}
-}
-
-// sourceFilePath returns the path of the file of the source key in svc's
-// cache, as README.md gives it: <state_dir>/cache/sources/<ab>/<cd>/<key>.
-func sourceFilePath(svc *testProxy, key imagerequest.SourceKey) string {
-	name := string(key)
-
-	return filepath.Join(svc.stateDir, "cache", "sources", name[0:2], name[2:4], name)
-}
-
-// variantFilePath returns the path of the file of the variant key in svc's
-// cache, as README.md gives it: <state_dir>/cache/variants/<ab>/<cd>/<key>.
-func variantFilePath(svc *testProxy, key imagerequest.VariantKey) string {
-	name := string(key)
-
-	return filepath.Join(svc.stateDir, "cache", "variants", name[0:2], name[2:4], name)
-}
-
-// setVariantLastAccessed backdates the last access time of a tracked
-// variant.
-func setVariantLastAccessed(
-	t *testing.T, db *sql.DB, key imagerequest.VariantKey, when time.Time,
-) {
-	t.Helper()
-
-	res, err := db.ExecContext(t.Context(),
-		`UPDATE variant_content SET last_accessed_at = ? WHERE cache_key = ?`,
-		when.UTC().Format(sqliteTimestampFormat), string(key),
-	)
-	if err != nil {
-		t.Fatalf("failed to set variant last_accessed_at: %v", err)
-	}
-
-	affected, err := res.RowsAffected()
-	if err != nil {
-		t.Fatalf("failed to read affected rows: %v", err)
-	}
-
-	if affected != 1 {
-		t.Fatalf("variant %s has no accounting row (affected=%d); "+
-			"stores must track variants in the database", key, affected)
-	}
-}
-
-// setSourceLastAccessed backdates the last access time of a tracked
-// source content blob.
-func setSourceLastAccessed(
-	t *testing.T, db *sql.DB, key imagerequest.SourceKey, when time.Time,
-) {
-	t.Helper()
-
-	res, err := db.ExecContext(t.Context(),
-		`UPDATE source_content SET last_accessed_at = ? WHERE source_key = ?`,
-		when.UTC().Format(sqliteTimestampFormat), string(key),
-	)
-	if err != nil {
-		t.Fatalf("failed to set source last_accessed_at: %v", err)
-	}
-
-	affected, err := res.RowsAffected()
-	if err != nil {
-		t.Fatalf("failed to read affected rows: %v", err)
-	}
-
-	if affected != 1 {
-		t.Fatalf("source %s has no accounting row (affected=%d)", key, affected)
-	}
-}
-
-// countRows returns the number of rows the given query yields.
-func countRows(t *testing.T, db *sql.DB, query string, args ...any) int {
-	t.Helper()
-
-	var n int
-
-	err := db.QueryRowContext(t.Context(), query, args...).Scan(&n)
-	if err != nil {
-		t.Fatalf("count query %q failed: %v", query, err)
-	}
-
-	return n
-}
-
-// setupTestDB creates an in-memory SQLite database for testing
-// using the production schema.
-func setupTestDB(t *testing.T) *sql.DB {
-	t.Helper()
-
-	db, err := sql.Open("sqlite", ":memory:")
-	if err != nil {
-		t.Fatalf("failed to open test db: %v", err)
-	}
-
-	// Use the real production schema via migrations
-	err = database.ApplyMigrations(context.Background(), db, nil)
-	if err != nil {
-		t.Fatalf("failed to apply migrations: %v", err)
-	}
-
-	return db
-}

internal/imagerequest/imagerequest.go

@@ -1,23 +1,22 @@
 // Package imagerequest holds the image request type, its parts, its checks,
-// the parsing of the /v1/image/ path, the variant key, the source key and the
-// source's upstream URL. It also holds the image format type and the MIME type
-// of each format. It imports no other package of this repo, so every package
-// that handles an image request can import it.
+// the parsing of the /v1/image/ path, the variant key and the source key. It
+// imports no other package of this repo, so every package that handles an
+// image request can import it.
 package imagerequest
 
 import (
 	"errors"
 	"net/url"
+	"time"
 )
 
 // ErrInvalidFitMode is returned when an invalid fit mode is provided.
 var ErrInvalidFitMode = errors.New("invalid fit mode")
 
-// Format is an image format. pixa reads and writes the formats from JPEG to
-// GIF below. In a request, orig and auto stand for one of them.
+// Format represents supported output image formats.
 type Format string
 
-// Supported image formats.
+// Supported image output formats.
 const (
 	FormatOriginal Format = "orig"
 	FormatJPEG     Format = "jpeg"
@@ -33,30 +32,6 @@ const (
 	FormatAuto Format = "auto"
 )
 
-// MIMEType returns the MIME type of the format, such as image/jpeg for
-// FormatJPEG. orig and auto stand for another format, so they have none:
-// MIMEType returns "" for them.
-func (f Format) MIMEType() string {
-	switch f {
-	case FormatJPEG:
-		return "image/jpeg"
-	case FormatPNG:
-		return "image/png"
-	case FormatWebP:
-		return "image/webp"
-	case FormatAVIF:
-		return "image/avif"
-	case FormatJXL:
-		return "image/jxl"
-	case FormatGIF:
-		return "image/gif"
-	case FormatOriginal, FormatAuto:
-		return ""
-	default:
-		return ""
-	}
-}
-
 // Size represents requested image dimensions
 type Size struct {
 	Width  int
@@ -110,13 +85,19 @@ func ValidateImageRequest(req *Request) error {
 }
 
 // Request represents a request for a processed image: the source to fetch
-// and the transform to apply to it. It holds exactly what the variant key
-// covers.
+// and the transform to apply to it.
 type Request struct {
 	// Source is what to fetch
 	Source Source
 	// Transform is what to do to it
 	Transform Transform
+	// Signature is the HMAC signature for non-allowlisted hosts
+	Signature string
+	// Expires is when the URL expires: the exp of a signed URL, or the expiry
+	// of an encrypted URL; the zero time if it has none
+	Expires time.Time
+	// AllowHTTP indicates whether HTTP (non-TLS) is allowed for this request
+	AllowHTTP bool
 }
 
 // Source is the image a request fetches from the origin.
@@ -144,20 +125,23 @@ type Transform struct {
 	FitMode Fit
 }
 
-// URL returns the source's upstream URL, with the scheme http when allowHTTP
-// is true and https otherwise. net/url writes its path percent-encoded again,
-// so each source path is one upstream path. Its query is the source query as
-// it is, with the characters escapeQuery encodes percent-encoded.
-func (s Source) URL(allowHTTP bool) *url.URL {
+// SourceURL returns the full upstream URL to fetch: the source path
+// percent-encoded again, as net/url writes a path, so each source path is one
+// upstream path, and the source query as it is, with the characters
+// escapeQuery encodes percent-encoded. Uses http:// scheme when AllowHTTP is
+// true, otherwise https://.
+func (r *Request) SourceURL() string {
 	scheme := "https"
-	if allowHTTP {
+	if r.AllowHTTP {
 		scheme = "http"
 	}
 
-	return &url.URL{
+	sourceURL := url.URL{
 		Scheme:   scheme,
-		Host:     s.Host,
-		Path:     s.Path,
-		RawQuery: escapeQuery(s.Query),
+		Host:     r.Source.Host,
+		Path:     r.Source.Path,
+		RawQuery: escapeQuery(r.Source.Query),
 	}
+
+	return sourceURL.String()
 }

internal/imagerequest/mimetype_internal_test.go

@@ -1,30 +0,0 @@
-package imagerequest
-
-import "testing"
-
-// TestFormat_MIMEType checks the MIME type of each format pixa reads and
-// writes, and that orig and auto have none.
-func TestFormat_MIMEType(t *testing.T) {
-	t.Parallel()
-
-	tests := []struct {
-		format Format
-		want   string
-	}{
-		{FormatJPEG, "image/jpeg"},
-		{FormatPNG, "image/png"},
-		{FormatWebP, "image/webp"},
-		{FormatAVIF, "image/avif"},
-		{FormatJXL, "image/jxl"},
-		{FormatGIF, "image/gif"},
-		{FormatOriginal, ""},
-		{FormatAuto, ""},
-	}
-
-	for _, tt := range tests {
-		got := tt.format.MIMEType()
-		if got != tt.want {
-			t.Errorf("%s MIMEType() = %q, want %q", tt.format, got, tt.want)
-		}
-	}
-}

internal/imagerequest/sourceurl_internal_test.go

@@ -2,49 +2,57 @@ package imagerequest
 
 import "testing"
 
-func TestSource_URL_DefaultHTTPS(t *testing.T) {
+func TestRequest_SourceURL_DefaultHTTPS(t *testing.T) {
 	t.Parallel()
 
-	source := Source{
-		Host:  testHostCDN,
-		Path:  testPathCat,
-		Query: "v=2",
+	req := &Request{
+		Source: Source{
+			Host:  testHostCDN,
+			Path:  testPathCat,
+			Query: "v=2",
+		},
 	}
 
-	got := source.URL(false).String()
+	got := req.SourceURL()
 
 	want := "https://cdn.example.com/photos/cat.jpg?v=2"
 	if got != want {
-		t.Errorf("URL() = %q, want %q", got, want)
+		t.Errorf("SourceURL() = %q, want %q", got, want)
 	}
 }
 
-func TestSource_URL_AllowHTTP(t *testing.T) {
+func TestRequest_SourceURL_AllowHTTP(t *testing.T) {
 	t.Parallel()
 
-	source := Source{
-		Host: "localhost:8080",
-		Path: testPathCat,
+	req := &Request{
+		Source: Source{
+			Host: "localhost:8080",
+			Path: testPathCat,
+		},
+		AllowHTTP: true,
 	}
 
-	got := source.URL(true).String()
+	got := req.SourceURL()
 
 	want := "http://localhost:8080/photos/cat.jpg"
 	if got != want {
-		t.Errorf("URL() = %q, want %q", got, want)
+		t.Errorf("SourceURL() = %q, want %q", got, want)
 	}
 }
 
-func TestSource_URL_AllowHTTPFalse(t *testing.T) {
+func TestRequest_SourceURL_AllowHTTPFalse(t *testing.T) {
 	t.Parallel()
 
-	source := Source{
-		Host: testHostCDN,
-		Path: "/img.jpg",
+	req := &Request{
+		Source: Source{
+			Host: testHostCDN,
+			Path: "/img.jpg",
+		},
+		AllowHTTP: false,
 	}
 
-	got := source.URL(false).String()
+	got := req.SourceURL()
 	if got != "https://cdn.example.com/img.jpg" {
-		t.Errorf("URL() = %q, want https scheme", got)
+		t.Errorf("SourceURL() = %q, want https scheme", got)
 	}
 }

internal/imagerequest/urlparser.go

@@ -66,6 +66,23 @@ var queryEscapeRegex = regexp.MustCompile(`%[0-9A-Fa-f]{2}|[^!-~]|["#'<>%]`)
 var hostRegex = regexp.MustCompile(
 	`^(?:[A-Za-z0-9_.-]+|\[([0-9A-Fa-f:.]+)\])(?::[0-9]*)?$`)
 
+// ParseImagePath parses an image URL's path after /v1/image/, decoded once:
+// <host>/<path>/<size>.<format>, or <host>/<path>/<size> for JPEG XL.
+// Examples:
+//   - cdn.example.com/photos/cat.jpg/800x600.webp
+//   - cdn.example.com/photos/cat.jpg/0x0.jpeg
+//   - cdn.example.com/photos/cat.jpg/orig.png
+//   - cdn.example.com/photos/cat.jpg/800x600
+func ParseImagePath(path string) (*Request, error) {
+	// Strip leading slash if present (chi may include it)
+	path = strings.TrimPrefix(path, "/")
+	if path == "" {
+		return nil, ErrMissingHost
+	}
+
+	return parseImageComponents(path)
+}
+
 // ParseImageURL parses an image URL's path, decoded once as r.URL.Path holds
 // it: /v1/image/<host>/<path>/<size>.<format>, or /v1/image/<host>/<path>/<size>
 // for JPEG XL. A source query follows the source path after a "?", which the
@@ -126,15 +143,15 @@ func parseImageComponents(remainder string) (*Request, error) {
 		return nil, ErrMissingHost
 	}
 
-	// Later steps put the host unparsed into the allowlist check, the cache key
-	// and the upstream URL, so only the forms hostRegex describes are accepted
+	// Only the forms hostRegex describes are accepted. A "?", "#" or "@" in
+	// the host would make Go's URL parser, which the allowlist check and the
+	// fetcher use, read a different host from the one allowlisted and cached
 	hostMatch := hostRegex.FindStringSubmatch(host)
 	if hostMatch == nil {
 		return nil, fmt.Errorf("%w: %q", ErrInvalidHost, host)
 	}
 
-	// The allowlist check and the fetcher drop the brackets, so brackets
-	// around anything but an IPv6 address would give a host a second spelling
+	// Go's URL parser refuses brackets around anything but an IPv6 address
 	if inBrackets := hostMatch[1]; inBrackets != "" {
 		addr, err := netip.ParseAddr(inBrackets)
 		if err != nil || !addr.Is6() {
@@ -147,8 +164,9 @@ func parseImageComponents(remainder string) (*Request, error) {
 	// host
 	host = strings.ToLower(host)
 
-	// A "#" starts a URL's fragment, so neither the source path nor the source
-	// query may hold one
+	// Go's URL parser, which the fetcher uses, reads a "#" as the start of a
+	// fragment and drops the rest, so each text after it would be another
+	// spelling, cached under its own keys, of one upstream request
 	if strings.Contains(path, "#") {
 		return nil, fmt.Errorf(
 			`%w: the source path or query holds a "#"`, ErrInvalidPath)

internal/imagerequest/urlparser_internal_test.go

@@ -192,16 +192,76 @@ func TestParseImageURL_Errors(t *testing.T) {
 	}
 }
 
-// TestParseImageURL_LowerCasesHost verifies that the host is lower-cased, so
+func TestParseImagePath(t *testing.T) {
+	t.Parallel()
+
+	// ParseImagePath is for chi wildcard capture (no /v1/image/ prefix)
+	tests := []struct {
+		name    string
+		input   string
+		want    *Request
+		wantErr bool
+	}{
+		{
+			name:  "chi wildcard capture",
+			input: "cdn.example.com/photos/cat.jpg/800x600.webp",
+			want: &Request{
+				Source: Source{
+					Host: testHostCDN,
+					Path: testPathCat,
+				},
+				Transform: Transform{
+					Size:   Size{Width: 800, Height: 600},
+					Format: FormatWebP,
+				},
+			},
+		},
+		{
+			name:  "with leading slash from chi",
+			input: "/cdn.example.com/photos/cat.jpg/800x600.webp",
+			want: &Request{
+				Source: Source{
+					Host: testHostCDN,
+					Path: testPathCat,
+				},
+				Transform: Transform{
+					Size:   Size{Width: 800, Height: 600},
+					Format: FormatWebP,
+				},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			got, err := ParseImagePath(tt.input)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("ParseImagePath() error = %v, wantErr %v", err, tt.wantErr)
+
+				return
+			}
+
+			if err != nil {
+				return
+			}
+
+			assertRequest(t, got, tt.want)
+		})
+	}
+}
+
+// TestParseImagePath_LowerCasesHost verifies that the host is lower-cased, so
 // that every spelling of its letter case is the same host to the allowlist,
 // the upstream connection limits and the cache, and that the path keeps its
 // case.
-func TestParseImageURL_LowerCasesHost(t *testing.T) {
+func TestParseImagePath_LowerCasesHost(t *testing.T) {
 	t.Parallel()
 
-	got, err := ParseImageURL("/v1/image/CDN.Example.COM/Photos/Cat.jpg/800x600.webp")
+	got, err := ParseImagePath("CDN.Example.COM/Photos/Cat.jpg/800x600.webp")
 	if err != nil {
-		t.Fatalf("ParseImageURL() error = %v", err)
+		t.Fatalf("ParseImagePath() error = %v", err)
 	}
 
 	t.Logf("parsed host %q, path %q", got.Source.Host, got.Source.Path)
@@ -215,21 +275,21 @@ func TestParseImageURL_LowerCasesHost(t *testing.T) {
 	}
 }
 
-// TestParseImageURL_RefusesUserinfo verifies that a host holding "@" is
+// TestParseImagePath_RefusesUserinfo verifies that a host holding "@" is
 // refused: a URL reads what comes before the "@" as a user name and password
 // and the rest as the host.
-func TestParseImageURL_RefusesUserinfo(t *testing.T) {
+func TestParseImagePath_RefusesUserinfo(t *testing.T) {
 	t.Parallel()
 
 	for _, input := range []string{
-		"/v1/image/user@cdn.example.com/photos/cat.jpg/800x600.webp",
-		"/v1/image/user:password@cdn.example.com/photos/cat.jpg/800x600.webp",
+		"user@cdn.example.com/photos/cat.jpg/800x600.webp",
+		"user:password@cdn.example.com/photos/cat.jpg/800x600.webp",
 	} {
-		got, err := ParseImageURL(input)
-		t.Logf("ParseImageURL(%q) = %+v, error = %v", input, got, err)
+		got, err := ParseImagePath(input)
+		t.Logf("ParseImagePath(%q) = %+v, error = %v", input, got, err)
 
 		if !errors.Is(err, ErrInvalidHost) {
-			t.Errorf("ParseImageURL(%q) error = %v, want %v",
+			t.Errorf("ParseImagePath(%q) error = %v, want %v",
 				input, err, ErrInvalidHost)
 		}
 	}
@@ -255,10 +315,6 @@ func TestParseImageURL_PathTraversal(t *testing.T) {
 			name:  "parent in middle of path",
 			input: "/v1/image/cdn.example.com/photos/../../../etc/passwd/800x600.jpeg",
 		},
-		{
-			name:  "parent directory in path",
-			input: "/v1/image/cdn.example.com/photos/../secret/800x600.jpeg",
-		},
 		{
 			name:  "encoded parent directory",
 			input: "/v1/image/cdn.example.com/photos/%2e%2e/secret/800x600.jpeg",
@@ -301,6 +357,40 @@ func TestParseImageURL_PathTraversal(t *testing.T) {
 	}
 }
 
+func TestParseImagePath_PathTraversal(t *testing.T) {
+	t.Parallel()
+
+	// Test path traversal via ParseImagePath (chi wildcard)
+	tests := []struct {
+		name  string
+		input string
+	}{
+		{
+			name:  "parent directory in path",
+			input: "cdn.example.com/photos/../secret/800x600.jpeg",
+		},
+		{
+			name:  "encoded traversal",
+			input: "cdn.example.com/photos/%2e%2e/secret/800x600.jpeg",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			_, err := ParseImagePath(tt.input)
+			if err == nil {
+				t.Error("ParseImagePath() should reject path traversal attempts")
+			}
+
+			if !errors.Is(err, ErrPathTraversal) {
+				t.Errorf("ParseImagePath() error = %v, want ErrPathTraversal", err)
+			}
+		})
+	}
+}
+
 // TestParseImageURL_SourceURLHoldingPercent25 verifies that a source path and
 // a source query holding %25, the percent-escape of a literal "%", are
 // accepted as they are, although decoding them once more leaves a "%" that

internal/imgcache/cache.go

@@ -1,10 +1,3 @@
-// Package imgcache is the image cache. It keeps:
-//   - the source images fetched from upstream
-//   - the variants made from them
-//   - the negative cache: the source URLs whose fetch failed recently
-//
-// Each image is a file with a row in the database. Eviction removes the
-// least recently used images to keep the cache under its size limit.
 package imgcache
 
 import (
@@ -15,11 +8,18 @@ import (
 	"io"
 	"log/slog"
 	"path/filepath"
+	"sync"
+	"sync/atomic"
 	"time"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"sneak.berlin/go/pixa/internal/httpfetcher"
 	"sneak.berlin/go/pixa/internal/imagerequest"
-	"sneak.berlin/go/pixa/internal/magic"
+)
+
+// Cache errors.
+var (
+	ErrCacheMiss     = errors.New("cache miss")
+	ErrNegativeCache = errors.New("negative cache hit")
 )
 
 // maxPendingAccessTimes is how many access times of variants served from
@@ -34,22 +34,29 @@ const maxPendingAccessTimes = 10000
 // have expired.
 const cleanExpiredBatchSize = 1000
 
-// DefaultNegativeTTL is how long pixad keeps a failed fetch in the negative
-// cache.
-const DefaultNegativeTTL = 5 * time.Minute
-
-// Config holds cache configuration.
-type Config struct {
+// CacheConfig holds cache configuration.
+type CacheConfig struct {
 	StateDir    string
 	NegativeTTL time.Duration
 
 	// MaxBytes is the disk cache size limit in bytes that eviction
-	// enforces. Zero turns the disk cache off entirely: no cache
-	// directories are created, lookups always miss, stores are no-ops,
-	// and the eviction goroutine only removes the expired negative cache
-	// rows.
+	// enforces. Zero means no limit is enforced (no eviction).
 	MaxBytes int64
 
+	// UseDefaultMaxBytes makes NewCache replace MaxBytes with the
+	// default limit: 75% of the sum of the space free on the filesystem
+	// holding the cache and the bytes the cache already holds, at least
+	// DefaultCacheMaxBytesFloor. The config layer sets this when the
+	// operator omits cache_max_bytes.
+	UseDefaultMaxBytes bool
+
+	// DisableDiskCache turns the disk cache off entirely: no cache
+	// directories are created, lookups always miss, stores are
+	// no-ops, and the eviction goroutine only removes the expired
+	// negative cache rows. The config layer sets this when the
+	// operator configures cache_max_bytes: 0.
+	DisableDiskCache bool
+
 	// Logger receives accounting and eviction log output. A nil
 	// Logger means slog.Default().
 	Logger *slog.Logger
@@ -58,11 +65,15 @@ type Config struct {
 // Cache implements the caching layer for the image proxy.
 type Cache struct {
 	db         *sql.DB
-	srcContent *FileStore // source images by source key
-	variants   *FileStore // processed variants by cache key
-	config     Config
+	srcContent *ContentStorage // source images by source key
+	variants   *VariantStorage // processed variants by cache key
+	config     CacheConfig
 	log        *slog.Logger
 
+	// disabled means the disk cache is turned off entirely: lookups
+	// always miss, stores are no-ops, and no eviction runs.
+	disabled bool
+
 	// Eviction machinery. The channels are created in NewCache so
 	// stores can signal write pressure without racing StartEviction.
 	// evictionCancel, set by StartEviction, cancels the eviction
@@ -71,27 +82,33 @@ type Cache struct {
 	evictionDone     chan struct{}
 	evictionCancel   context.CancelFunc
 
-	// pendingVariantAccessTimes holds the variants served from the cache,
-	// and pendingSourceAccessTimes the cached sources a miss used, whose
-	// access time is still to be written by the goroutine that
-	// StartPendingAccessTimeWrites starts, so that no request waits for the
-	// database to record it. As for eviction, the channels are created in
+	// The pending counts: hits, misses, upstream fetches and transforms
+	// that requests counted, kept here until they are written by the
+	// goroutine that StartPendingCountWrites starts, so that no request
+	// waits for the database to count it. pendingVariantAccessTimes holds
+	// the variants served from the cache, and pendingSourceAccessTimes the
+	// cached sources a miss used, whose access time is still to be written
+	// by that goroutine. As for eviction, the channels are created in
 	// NewCache, so that requests can hand over access times before that
-	// goroutine starts; pendingAccessTimesDone is closed when it returns.
-	// pendingAccessTimesCancel, set by StartPendingAccessTimeWrites,
-	// cancels its context, which tells it to finish.
+	// goroutine starts; pendingCountsDone is closed when it returns.
+	// pendingCountsCancel, set by StartPendingCountWrites, cancels its
+	// context, which tells it to finish.
+	pendingHits               atomic.Int64
+	pendingMisses             atomic.Int64
+	pendingUpstreamFetches    atomic.Int64
+	pendingUpstreamFetchBytes atomic.Int64
+	pendingTransforms         atomic.Int64
 	pendingVariantAccessTimes chan imagerequest.VariantKey
 	pendingSourceAccessTimes  chan imagerequest.SourceKey
-	pendingAccessTimesDone    chan struct{}
-	pendingAccessTimesCancel  context.CancelFunc
+	pendingCountsDone         chan struct{}
+	pendingCountsCancel       context.CancelFunc
 
-	// The counts of cache hits and misses, made and registered by
-	// registerCounters (see counters.go)
-	cacheHits   prometheus.Counter
-	cacheMisses prometheus.Counter
+	// Held through each write of the pending counts, and by
+	// readHitAndMissCounts to read them
+	pendingCountsWriteMutex sync.Mutex
 
 	// reconciliationPageSize is the most rows one read of a content table
-	// returns in the reconciliation pass. NewCache sets it to
+	// returns in the reconciliation pass and in Stats. newCache sets it to
 	// defaultReconciliationPageSize; tests set it smaller.
 	reconciliationPageSize int
 
@@ -102,11 +119,15 @@ type Cache struct {
 	reconciliationReadTestHook func(rows int)
 }
 
-// NewCache creates a new cache instance and registers its counters on
-// metricsRegistry. pixad passes Prometheus' default registry, the one
-// /metrics serves. It makes no database call.
-func NewCache(
-	db *sql.DB, config Config, metricsRegistry prometheus.Registerer,
+// NewCache creates a new cache instance.
+func NewCache(db *sql.DB, config CacheConfig) (*Cache, error) {
+	return newCache(db, config, defaultFreeSpaceProbe)
+}
+
+// newCache is NewCache with the free-space probe passed in, so tests
+// can fake the free space the default limit is worked out from.
+func newCache(
+	db *sql.DB, config CacheConfig, probe FreeSpaceProbeFunc,
 ) (*Cache, error) {
 	log := config.Logger
 	if log == nil {
@@ -117,33 +138,29 @@ func NewCache(
 		db:               db,
 		config:           config,
 		log:              log,
+		disabled:         config.DisableDiskCache,
 		evictionPressure: make(chan struct{}, 1),
 		evictionDone:     make(chan struct{}),
 
 		pendingVariantAccessTimes: make(chan imagerequest.VariantKey, maxPendingAccessTimes),
 		pendingSourceAccessTimes:  make(chan imagerequest.SourceKey, maxPendingAccessTimes),
-		pendingAccessTimesDone:    make(chan struct{}),
+		pendingCountsDone:         make(chan struct{}),
 
 		reconciliationPageSize: defaultReconciliationPageSize,
 	}
 
-	err := c.registerCounters(metricsRegistry)
-	if err != nil {
-		return nil, err
-	}
-
-	if config.MaxBytes == 0 {
+	if c.disabled {
 		return c, nil
 	}
 
-	srcContent, err := NewFileStore(
+	srcContent, err := NewContentStorage(
 		filepath.Join(config.StateDir, "cache", "sources"),
 	)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create source content storage: %w", err)
 	}
 
-	variants, err := NewFileStore(
+	variants, err := NewVariantStorage(
 		filepath.Join(config.StateDir, "cache", "variants"),
 	)
 	if err != nil {
@@ -153,137 +170,51 @@ func NewCache(
 	c.srcContent = srcContent
 	c.variants = variants
 
+	if config.UseDefaultMaxBytes {
+		limit, err := c.computeDefaultMaxBytes(context.Background(), probe)
+		if err != nil {
+			return nil, err
+		}
+
+		c.config.MaxBytes = limit
+
+		log.Info("computed default cache size limit from free space and cache contents",
+			"cache_max_bytes", limit,
+			"cache_dir", filepath.Join(config.StateDir, "cache"),
+		)
+	}
+
 	return c, nil
 }
 
-// Variant opens a cached variant and returns a reader, its size and its
+// GetVariant opens a cached variant and returns a reader, its size and its
 // content type, read from the variant file's first bytes. It opens that one
-// file and makes no database call. A variant it opens has its access time
-// handed to the background writer without waiting (see touchVariant). A
-// variant not in the cache, or any variant of a disabled cache, is
-// ErrNotFound; a variant file whose first bytes are not those of an output
-// format is another error.
-func (c *Cache) Variant(
+// file and makes no database call. A variant not in the cache, or any
+// variant of a disabled cache, is ErrNotFound; a variant file whose first
+// bytes are not those of an output format is another error.
+func (c *Cache) GetVariant(
 	cacheKey imagerequest.VariantKey,
 ) (io.ReadCloser, int64, string, error) {
-	if c.config.MaxBytes == 0 {
+	if c.disabled {
 		return nil, 0, "", ErrNotFound
 	}
 
-	file, size, err := c.variants.Open(string(cacheKey))
-	if err != nil {
-		return nil, 0, "", err
-	}
-
-	format, err := readFormat(file)
-	if err != nil {
-		_ = file.Close()
-
-		return nil, 0, "", err
-	}
-
-	c.touchVariant(cacheKey)
-
-	return file, size, format.MIMEType(), nil
+	return c.variants.LoadWithContentType(cacheKey)
 }
 
-// PutVariant stores a processed variant by its cache key and records
-// it in the size accounting. On a disabled cache it is a no-op. The
-// accounting insert is best-effort (the startup reconciliation pass
-// adopts any variant file that misses its accounting row).
-func (c *Cache) PutVariant(
-	ctx context.Context, cacheKey imagerequest.VariantKey, content io.Reader,
-) error {
-	if c.config.MaxBytes == 0 {
-		return nil
-	}
-
-	data, err := io.ReadAll(content)
-	if err != nil {
-		return fmt.Errorf("failed to read content: %w", err)
-	}
-
-	err = c.variants.Write(string(cacheKey), data)
-	if err != nil {
-		return err
-	}
-
-	size := int64(len(data))
-
-	_, err = c.db.ExecContext(ctx, `
-		INSERT INTO variant_content (cache_key, size_bytes)
-		VALUES (?, ?)
-		ON CONFLICT(cache_key) DO UPDATE SET
-			size_bytes = excluded.size_bytes,
-			last_accessed_at = CURRENT_TIMESTAMP
-	`, string(cacheKey), size)
-	if err != nil {
-		c.log.Warn("failed to record variant in size accounting",
-			"cache_key", cacheKey, "error", err)
-	}
-
-	c.notifyWritePressure()
-
-	return nil
-}
-
-// Source opens the cached source of src and returns a reader, its size in
-// bytes and its format, read from the file's first bytes. A source whose row
-// or file is missing is ErrNotFound, as is any source of a disabled cache; a
-// file whose first bytes are not those of a source format is another error.
-// A source it opens has its access time handed to the background writer
-// without waiting (see touchSourceContent).
-func (c *Cache) Source(
-	ctx context.Context, src imagerequest.Source,
-) (io.ReadCloser, int64, imagerequest.Format, error) {
-	if c.config.MaxBytes == 0 {
-		return nil, 0, "", ErrNotFound
-	}
-
-	key := src.Key()
-
-	var rowExists bool
-
-	err := c.db.QueryRowContext(ctx, `
-		SELECT EXISTS(SELECT 1 FROM source_content WHERE source_key = ?)
-	`, string(key)).Scan(&rowExists)
-	if err != nil {
-		return nil, 0, "", fmt.Errorf("failed to lookup source: %w", err)
-	}
-
-	if !rowExists {
-		return nil, 0, "", ErrNotFound
-	}
-
-	file, size, err := c.srcContent.Open(string(key))
-	if err != nil {
-		return nil, 0, "", err
-	}
-
-	format, err := readFormat(file)
-	if err != nil {
-		_ = file.Close()
-
-		return nil, 0, "", err
-	}
-
-	c.touchSourceContent(key)
-
-	return file, size, format, nil
-}
-
-// PutSource stores fetched source content: it writes the file named by
+// StoreSource stores fetched source content: it writes the file named by
 // the source's key, then the source's row. When the row cannot be written
 // the file is removed and the store fails, as a file with no row is never
 // served or evicted; if that removal fails too, the next reconciliation
 // pass removes the file. On a disabled cache it is a no-op returning an
 // empty key.
-func (c *Cache) PutSource(
+func (c *Cache) StoreSource(
 	ctx context.Context,
-	src imagerequest.Source,
+	req *imagerequest.Request,
 	content io.Reader,
+	result *httpfetcher.FetchResult,
 ) (imagerequest.SourceKey, error) {
-	if c.config.MaxBytes == 0 {
+	if c.disabled {
 		return "", nil
 	}
 
@@ -292,24 +223,27 @@ func (c *Cache) PutSource(
 		return "", fmt.Errorf("failed to read source content: %w", err)
 	}
 
-	key := src.Key()
+	key := req.Source.Key()
 
-	err = c.srcContent.Write(string(key), data)
+	size, err := c.srcContent.Store(key, data)
 	if err != nil {
 		return "", fmt.Errorf("failed to store source content: %w", err)
 	}
 
-	size := int64(len(data))
-
 	_, err = c.db.ExecContext(ctx, `
-		INSERT INTO source_content (source_key, size_bytes)
-		VALUES (?, ?)
+		INSERT INTO source_content
+			(source_key, source_host, source_path, source_query,
+			 content_type, size_bytes)
+		VALUES (?, ?, ?, ?, ?, ?)
 		ON CONFLICT(source_key) DO UPDATE SET
+			content_type = excluded.content_type,
 			size_bytes = excluded.size_bytes,
+			fetched_at = CURRENT_TIMESTAMP,
 			last_accessed_at = CURRENT_TIMESTAMP
-	`, string(key), size)
+	`, string(key), req.Source.Host, req.Source.Path, req.Source.Query,
+		result.ContentType, size)
 	if err != nil {
-		deleteErr := c.srcContent.Delete(string(key))
+		deleteErr := c.srcContent.Delete(key)
 		if deleteErr != nil {
 			c.log.Warn("failed to remove source file whose row was not written",
 				"source_key", key, "error", deleteErr)
@@ -323,43 +257,96 @@ func (c *Cache) PutSource(
 	return key, nil
 }
 
-// Failure reports whether src is in the negative cache. It only reads: a
-// row past its expiry is not a hit, and the eviction goroutine deletes it
-// with the other expired rows (see CleanExpired).
-func (c *Cache) Failure(
-	ctx context.Context, src imagerequest.Source,
-) (bool, error) {
-	var expiresAt time.Time
+// StoreVariant stores a processed variant by its cache key and records
+// it in the size accounting. On a disabled cache it is a no-op. The
+// accounting insert is best-effort (the startup reconciliation pass
+// adopts any variant file that misses its accounting row).
+func (c *Cache) StoreVariant(
+	ctx context.Context, cacheKey imagerequest.VariantKey,
+	content io.Reader, contentType string,
+) error {
+	if c.disabled {
+		return nil
+	}
+
+	size, err := c.variants.Store(cacheKey, content)
+	if err != nil {
+		return err
+	}
+
+	_, err = c.db.ExecContext(ctx, `
+		INSERT INTO variant_content (cache_key, size_bytes, content_type)
+		VALUES (?, ?, ?)
+		ON CONFLICT(cache_key) DO UPDATE SET
+			size_bytes = excluded.size_bytes,
+			content_type = excluded.content_type,
+			last_accessed_at = CURRENT_TIMESTAMP
+	`, string(cacheKey), size, contentType)
+	if err != nil {
+		c.log.Warn("failed to record variant in size accounting",
+			"cache_key", cacheKey, "error", err)
+	}
+
+	c.notifyWritePressure()
+
+	return nil
+}
+
+// LookupSource checks if we have cached source content for a request.
+// Returns the source key and content type if found, or empty values
+// if not; a row whose file is missing is not found. A source found has
+// its access time handed to the background writer without waiting (see
+// touchSourceContent); a disabled cache always reports no cached source.
+func (c *Cache) LookupSource(
+	ctx context.Context, req *imagerequest.Request,
+) (imagerequest.SourceKey, string, error) {
+	if c.disabled {
+		return "", "", nil
+	}
+
+	key := req.Source.Key()
+
+	var contentType string
 
 	err := c.db.QueryRowContext(ctx, `
-		SELECT expires_at FROM negative_cache
-		WHERE source_host = ? AND source_path = ? AND source_query = ?
-	`, src.Host, src.Path, src.Query).Scan(&expiresAt)
+		SELECT content_type FROM source_content WHERE source_key = ?
+	`, string(key)).Scan(&contentType)
 
 	if errors.Is(err, sql.ErrNoRows) {
-		return false, nil
+		return "", "", nil
 	}
 
 	if err != nil {
-		return false, fmt.Errorf("failed to check negative cache: %w", err)
+		return "", "", fmt.Errorf("failed to lookup source: %w", err)
 	}
 
-	expired := time.Now().After(expiresAt)
+	// Verify the content file exists
+	if !c.srcContent.Exists(key) {
+		return "", "", nil
+	}
 
-	return !expired, nil
+	c.touchSourceContent(key)
+
+	return key, contentType, nil
 }
 
-// PutFailure stores a negative cache entry for src, whose fetch failed.
-func (c *Cache) PutFailure(ctx context.Context, src imagerequest.Source) error {
+// StoreNegative stores a negative cache entry for a failed fetch.
+func (c *Cache) StoreNegative(
+	ctx context.Context, req *imagerequest.Request, statusCode int, errMsg string,
+) error {
 	expiresAt := time.Now().UTC().Add(c.config.NegativeTTL)
 
 	_, err := c.db.ExecContext(ctx, `
 		INSERT INTO negative_cache
-			(source_host, source_path, source_query, expires_at)
-		VALUES (?, ?, ?, ?)
+			(source_host, source_path, source_query, status_code,
+			 error_message, expires_at)
+		VALUES (?, ?, ?, ?, ?, ?)
 		ON CONFLICT(source_host, source_path, source_query) DO UPDATE SET
+			status_code = excluded.status_code,
+			error_message = excluded.error_message,
+			fetched_at = CURRENT_TIMESTAMP,
 			expires_at = excluded.expires_at
-	`, src.Host, src.Path, src.Query, expiresAt)
+	`, req.Source.Host, req.Source.Path, req.Source.Query, statusCode, errMsg, expiresAt)
 	if err != nil {
 		return fmt.Errorf("failed to insert negative cache: %w", err)
 	}
@@ -367,6 +354,18 @@ func (c *Cache) PutFailure(ctx context.Context, src imagerequest.Source) error {
 	return nil
 }
 
+// GetSourceContent returns a reader for cached source content by its key,
+// and the content's size in bytes.
+func (c *Cache) GetSourceContent(
+	key imagerequest.SourceKey,
+) (io.ReadCloser, int64, error) {
+	if c.disabled {
+		return nil, 0, ErrNotFound
+	}
+
+	return c.srcContent.LoadWithSize(key)
+}
+
 // CleanExpired removes the negative cache rows past their expiry, one
 // batch per statement, until none is left. Once ctx ends it starts no
 // further batch and returns ctx's error. The eviction goroutine calls it
@@ -390,20 +389,94 @@ func (c *Cache) CleanExpired(ctx context.Context) error {
 	}
 }
 
-// IncrementStats counts a cache hit or miss. It only adds to the cache's
-// Prometheus counters in memory (see counters.go), so it never waits for the
-// database or fails.
-func (c *Cache) IncrementStats(hit bool) {
-	if hit {
-		c.cacheHits.Inc()
-	} else {
-		c.cacheMisses.Inc()
+// Stats returns cache statistics.
+func (c *Cache) Stats(ctx context.Context) (*CacheStats, error) {
+	var stats CacheStats
+
+	err := c.readHitAndMissCounts(ctx, &stats)
+	if err != nil && !errors.Is(err, sql.ErrNoRows) {
+		return nil, fmt.Errorf("failed to get cache stats: %w", err)
 	}
+
+	// Count and size the cached source images and processed variants from
+	// their tables. A disabled cache holds none, whatever rows an earlier
+	// run left.
+	if !c.disabled {
+		err = c.db.QueryRowContext(ctx, `
+			SELECT (SELECT COUNT(*) FROM source_content)
+			     + (SELECT COUNT(*) FROM variant_content)
+		`).Scan(&stats.TotalItems)
+		if err != nil {
+			c.log.Warn("failed to count cache items for stats", "error", err)
+		}
+
+		stats.TotalSizeBytes, err = c.sumContentSizeBytes(ctx)
+		if err != nil {
+			c.log.Warn("failed to sum cache size for stats", "error", err)
+		}
+	}
+
+	// Compute hit rate as a ratio
+	if stats.HitCount+stats.MissCount > 0 {
+		stats.HitRate = float64(stats.HitCount) / float64(stats.HitCount+stats.MissCount)
+	}
+
+	return &stats, nil
+}
+
+// IncrementStats counts a cache hit or miss, and an upstream fetch that read
+// fetchBytes bytes, as IncrementUpstreamFetch does. Like the other Increment
+// methods, it only adds to the pending counts, which the goroutine
+// StartPendingCountWrites starts writes to the database, so it never waits
+// for the database or fails.
+func (c *Cache) IncrementStats(hit bool, fetchBytes int64) {
+	if hit {
+		c.pendingHits.Add(1)
+	} else {
+		c.pendingMisses.Add(1)
+	}
+
+	c.IncrementUpstreamFetch(fetchBytes)
+}
+
+// IncrementUpstreamFetch counts one upstream fetch that read fetchBytes bytes.
+// A fetch that read no bytes is not counted.
+func (c *Cache) IncrementUpstreamFetch(fetchBytes int64) {
+	if fetchBytes <= 0 {
+		return
+	}
+
+	c.pendingUpstreamFetches.Add(1)
+	c.pendingUpstreamFetchBytes.Add(fetchBytes)
+}
+
+// IncrementTransformCount counts one image transcoded by the image processor.
+func (c *Cache) IncrementTransformCount() {
+	c.pendingTransforms.Add(1)
+}
+
+// readHitAndMissCounts sets the hit and miss counts of stats to those of the
+// cache_stats row plus the pending hits and misses (see
+// StartPendingCountWrites). It holds pendingCountsWriteMutex, so that no
+// write of the pending counts falls between the two reads.
+func (c *Cache) readHitAndMissCounts(ctx context.Context, stats *CacheStats) error {
+	c.pendingCountsWriteMutex.Lock()
+	defer c.pendingCountsWriteMutex.Unlock()
+
+	err := c.db.QueryRowContext(ctx, `
+		SELECT hit_count, miss_count
+		FROM cache_stats WHERE id = 1
+	`).Scan(&stats.HitCount, &stats.MissCount)
+
+	stats.HitCount += c.pendingHits.Load()
+	stats.MissCount += c.pendingMisses.Load()
+
+	return err
 }
 
 // touchVariant hands the access time of a variant served from the cache to
-// the goroutine StartPendingAccessTimeWrites starts, which writes it in its
-// next batch. It never waits: while maxPendingAccessTimes access times of
+// the goroutine StartPendingCountWrites starts, which writes it in its next
+// batch. It never waits: while maxPendingAccessTimes access times of
 // variants wait to be written, this one is dropped, and the variant only
 // looks colder to eviction.
 func (c *Cache) touchVariant(cacheKey imagerequest.VariantKey) {
@@ -414,10 +487,10 @@ func (c *Cache) touchVariant(cacheKey imagerequest.VariantKey) {
 }
 
 // touchSourceContent hands the access time of a cached source a miss used to
-// the goroutine StartPendingAccessTimeWrites starts, which writes it in its
-// next batch. It never waits: while maxPendingAccessTimes access times of
-// sources wait to be written, this one is dropped, and the source only looks
-// colder to eviction.
+// the goroutine StartPendingCountWrites starts, which writes it in its next
+// batch. It never waits: while maxPendingAccessTimes access times of sources
+// wait to be written, this one is dropped, and the source only looks colder
+// to eviction.
 func (c *Cache) touchSourceContent(key imagerequest.SourceKey) {
 	select {
 	case c.pendingSourceAccessTimes <- key:
@@ -425,6 +498,32 @@ func (c *Cache) touchSourceContent(key imagerequest.SourceKey) {
 	}
 }
 
+// checkNegativeCache checks if a request is in the negative cache. It only
+// reads: a row past its expiry is not a hit, and the eviction goroutine
+// deletes it with the other expired rows (see CleanExpired).
+func (c *Cache) checkNegativeCache(
+	ctx context.Context, req *imagerequest.Request,
+) (bool, error) {
+	var expiresAt time.Time
+
+	err := c.db.QueryRowContext(ctx, `
+		SELECT expires_at FROM negative_cache
+		WHERE source_host = ? AND source_path = ? AND source_query = ?
+	`, req.Source.Host, req.Source.Path, req.Source.Query).Scan(&expiresAt)
+
+	if errors.Is(err, sql.ErrNoRows) {
+		return false, nil
+	}
+
+	if err != nil {
+		return false, fmt.Errorf("failed to check negative cache: %w", err)
+	}
+
+	expired := time.Now().After(expiresAt)
+
+	return !expired, nil
+}
+
 // cleanExpiredBatch deletes up to cleanExpiredBatchSize negative cache
 // rows past their expiry in one statement, and returns how many it
 // deleted. DELETE ... LIMIT needs a SQLite build option, so the subquery
@@ -448,17 +547,3 @@ func (c *Cache) cleanExpiredBatch(ctx context.Context) (int64, error) {
 
 	return deleted, nil
 }
-
-// readFormat reads the first bytes of a source or variant file, without
-// moving its offset, and returns the format they show. Sources and variants
-// are in the same six formats.
-func readFormat(content io.ReaderAt) (imagerequest.Format, error) {
-	firstBytes := make([]byte, magic.MinMagicBytes)
-
-	_, err := content.ReadAt(firstBytes, 0)
-	if err != nil {
-		return "", fmt.Errorf("failed to read the first bytes: %w", err)
-	}
-
-	return magic.DetectFormat(firstBytes)
-}

internal/imgcache/cache_hit_internal_test.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"image/color"
 	"io"
+	"os"
 	"testing"
 	"time"
 
@@ -14,17 +15,15 @@ import (
 	"sneak.berlin/go/pixa/internal/magic"
 )
 
-// TestVariant_ContentTypeFromFirstBytes stores an image in each output
-// format as a variant and checks that Variant serves it whole with the
-// content type of its format, read from the file.
-func TestVariant_ContentTypeFromFirstBytes(t *testing.T) {
+// TestGetVariant_ContentTypeFromFirstBytes stores an image in each output
+// format as a variant, recorded with the content type text/plain, and checks
+// that GetVariant serves it whole with the content type of its format, read
+// from the file.
+func TestGetVariant_ContentTypeFromFirstBytes(t *testing.T) {
 	t.Parallel()
 
 	cache, _ := newEvictionTestCache(t, 1<<30)
-	processor := imageprocessor.New(imageprocessor.Params{
-		MaxInputBytes:           50 << 20,
-		MaxConcurrentProcessing: 1,
-	})
+	processor := imageprocessor.New(imageprocessor.Params{})
 	source := generateTestJPEG(t, 40, 30, color.RGBA{200, 40, 40, 255})
 
 	for _, format := range []imagerequest.Format{
@@ -32,7 +31,7 @@ func TestVariant_ContentTypeFromFirstBytes(t *testing.T) {
 		imagerequest.FormatWebP, imagerequest.FormatAVIF, imagerequest.FormatJXL,
 	} {
 		result, err := processor.Process(t.Context(), bytes.NewReader(source),
-			imagerequest.FormatJPEG, &imagerequest.Transform{
+			&imagerequest.Transform{
 				Size:    imagerequest.Size{Width: 20, Height: 15},
 				Format:  format,
 				Quality: 85,
@@ -49,14 +48,14 @@ func TestVariant_ContentTypeFromFirstBytes(t *testing.T) {
 
 		key := imagerequest.VariantKey("aabbccdd10" + string(format))
 
-		err = cache.PutVariant(t.Context(), key, bytes.NewReader(image))
+		err = cache.StoreVariant(t.Context(), key, bytes.NewReader(image), "text/plain")
 		if err != nil {
-			t.Fatalf("PutVariant(%s) error = %v", format, err)
+			t.Fatalf("StoreVariant(%s) error = %v", format, err)
 		}
 
-		reader, size, contentType, err := cache.Variant(key)
+		reader, size, contentType, err := cache.GetVariant(key)
 		if err != nil {
-			t.Fatalf("Variant(%s) error = %v", format, err)
+			t.Fatalf("GetVariant(%s) error = %v", format, err)
 		}
 
 		served, err := io.ReadAll(reader)
@@ -68,7 +67,7 @@ func TestVariant_ContentTypeFromFirstBytes(t *testing.T) {
 
 		t.Logf("%s: %d bytes served as %s", format, size, contentType)
 
-		if want := format.MIMEType(); contentType != want {
+		if want := imageprocessor.FormatToMIME(format); contentType != want {
 			t.Errorf("%s variant content type = %q, want %q", format, contentType, want)
 		}
 
@@ -79,11 +78,11 @@ func TestVariant_ContentTypeFromFirstBytes(t *testing.T) {
 	}
 }
 
-// TestVariant_RefusesFileOfNoOutputFormat checks that Variant refuses
+// TestGetVariant_RefusesFileOfNoOutputFormat checks that GetVariant refuses
 // a variant file whose first bytes are not those of an output format, with
 // an error other than ErrNotFound, and that a variant with no file, or any
 // variant of a disabled cache, is ErrNotFound.
-func TestVariant_RefusesFileOfNoOutputFormat(t *testing.T) {
+func TestGetVariant_RefusesFileOfNoOutputFormat(t *testing.T) {
 	t.Parallel()
 
 	cache, _ := newEvictionTestCache(t, 1<<30)
@@ -96,7 +95,7 @@ func TestVariant_RefusesFileOfNoOutputFormat(t *testing.T) {
 	}{
 		{"text", []byte("this is text, not an image"), magic.ErrUnknownFormat},
 		{"SVG", []byte(`<svg xmlns="http://www.w3.org/2000/svg"></svg>`),
-			magic.ErrUnknownFormat},
+			errNotAnOutputFormat},
 		{"JPEG cut to 10 bytes", jpegImage[:10], io.EOF},
 		{"empty", nil, io.EOF},
 	}
@@ -104,35 +103,121 @@ func TestVariant_RefusesFileOfNoOutputFormat(t *testing.T) {
 	for i, tt := range tests {
 		key := imagerequest.VariantKey(fmt.Sprintf("aabbccdd20%02d", i))
 
-		err := cache.variants.Write(string(key), tt.content)
+		_, err := cache.variants.Store(key, bytes.NewReader(tt.content))
 		if err != nil {
 			t.Fatalf("%s: storing the variant file: %v", tt.name, err)
 		}
 
-		reader, _, contentType, err := cache.Variant(key)
-		t.Logf("%s: Variant() error = %v", tt.name, err)
+		reader, _, contentType, err := cache.GetVariant(key)
+		t.Logf("%s: GetVariant() error = %v", tt.name, err)
 
 		if reader != nil || contentType != "" || !errors.Is(err, tt.wantErr) {
-			t.Errorf("%s: Variant() = reader %v, content type %q, error %v; "+
+			t.Errorf("%s: GetVariant() = reader %v, content type %q, error %v; "+
 				"want no reader and %v", tt.name, reader, contentType, err, tt.wantErr)
 		}
 	}
 
-	reader, _, _, err := cache.Variant(testVariantKeyFour)
+	reader, _, _, err := cache.GetVariant(testVariantKeyFour)
 	if reader != nil || !errors.Is(err, ErrNotFound) {
-		t.Errorf("Variant() of a variant with no file = reader %v, error %v; "+
+		t.Errorf("GetVariant() of a variant with no file = reader %v, error %v; "+
 			"want no reader and %v", reader, err, ErrNotFound)
 	}
 
 	disabled, _ := newEvictionTestCache(t, 0)
 
-	reader, _, _, err = disabled.Variant(testVariantKeyOne)
+	reader, _, _, err = disabled.GetVariant(testVariantKeyOne)
 	if reader != nil || !errors.Is(err, ErrNotFound) {
-		t.Errorf("Variant() on a disabled cache = reader %v, error %v; "+
+		t.Errorf("GetVariant() on a disabled cache = reader %v, error %v; "+
 			"want no reader and %v", reader, err, ErrNotFound)
 	}
 }
 
+// TestService_Get_MakesAgainVariantOfNoOutputFormat replaces a cached
+// variant's file with text, and checks that the next request is a miss
+// answered with the variant made again, and the one after a hit.
+func TestService_Get_MakesAgainVariantOfNoOutputFormat(t *testing.T) {
+	t.Parallel()
+
+	svc, fixtures := SetupTestService(t)
+	req := photoVariant(fixtures, 85, imagerequest.FitCover)
+
+	want, _ := getImage(t, svc, req)
+
+	path := svc.cache.variants.keyToPath(imagerequest.CacheKey(req))
+
+	err := os.WriteFile(path, []byte("this is text, not an image"), StorageFilePerm)
+	if err != nil {
+		t.Fatalf("replacing the variant file: %v", err)
+	}
+
+	got, status := getImage(t, svc, req)
+	t.Logf("after the replacement: %d bytes, %s", len(got), status)
+
+	if status != CacheMiss || !bytes.Equal(got, want) {
+		t.Errorf("after the replacement: Get() = %d bytes, %s; want the %d bytes "+
+			"made again, %s", len(got), status, len(want), CacheMiss)
+	}
+
+	got, status = getImage(t, svc, req)
+
+	if status != CacheHit || !bytes.Equal(got, want) {
+		t.Errorf("next request: Get() = %d bytes, %s; want the %d bytes, %s",
+			len(got), status, len(want), CacheHit)
+	}
+}
+
+// TestService_Get_HitWaitsForNoDatabaseWrite holds the database's one
+// connection while a cached variant is requested. The hit must be answered
+// while the connection is still held, and its access time and hit count
+// must reach the database once it is free.
+func TestService_Get_HitWaitsForNoDatabaseWrite(t *testing.T) {
+	t.Parallel()
+
+	svc, fixtures := SetupTestService(t)
+	req := photoVariant(fixtures, 85, imagerequest.FitCover)
+	key := imagerequest.CacheKey(req)
+
+	getImage(t, svc, req)
+	waitForPendingCountsWritten(t, svc.cache)
+
+	anHourAgo := time.Now().Add(-time.Hour)
+	setVariantLastAccessed(t, svc.cache, key, anHourAgo)
+
+	want := readCacheStatsCounters(t, svc.cache)
+	want.hitCount++
+
+	releaseDatabase := holdDatabase(t, svc.cache)
+	defer releaseDatabase()
+
+	results := startGet(t.Context(), svc, req)
+
+	select {
+	case got := <-results:
+		if got.err != nil {
+			t.Fatalf("Get() of the cached variant error = %v", got.err)
+		}
+	case <-time.After(pendingCountsWait):
+		t.Fatal("the cache hit waited for the database")
+	}
+
+	releaseDatabase()
+
+	waitForCounters(t, svc.cache, want)
+
+	deadline := time.Now().Add(pendingCountsWait)
+
+	for countRows(t, svc.cache, `
+		SELECT COUNT(*) FROM variant_content
+		WHERE cache_key = ? AND last_accessed_at > ?
+	`, string(key), anHourAgo.UTC().Format(sqliteTimestampFormat)) == 0 {
+		if time.Now().After(deadline) {
+			t.Fatal("the hit's access time was not written")
+		}
+
+		time.Sleep(10 * time.Millisecond)
+	}
+}
+
 // TestTouchVariantAndTouchSourceContent_DropAccessTimesPastTheLimit hands one
 // more access time of a variant, and one more of a source, than may wait to
 // be written. touchVariant and touchSourceContent must return each time
@@ -155,7 +240,7 @@ func TestTouchVariantAndTouchSourceContent_DropAccessTimesPastTheLimit(t *testin
 
 	select {
 	case <-done:
-	case <-time.After(pendingAccessTimesWait):
+	case <-time.After(pendingCountsWait):
 		t.Fatal("touchVariant or touchSourceContent waited once the access " +
 			"times reached the limit")
 	}
@@ -171,11 +256,11 @@ func TestTouchVariantAndTouchSourceContent_DropAccessTimesPastTheLimit(t *testin
 	}
 }
 
-// TestStopPendingAccessTimeWrites_WritesPendingAccessTimes hands the access
-// time of one of two variants, three times, then stops the goroutine that
-// writes them, which never started. The stop must write that access time and
+// TestStopPendingCountWrites_WritesPendingAccessTimes hands the access time
+// of one of two variants, three times, then stops the goroutine that writes
+// them, which never started. The stop must write that access time and
 // leave the other variant's.
-func TestStopPendingAccessTimeWrites_WritesPendingAccessTimes(t *testing.T) {
+func TestStopPendingCountWrites_WritesPendingAccessTimes(t *testing.T) {
 	t.Parallel()
 
 	cache, _ := newEvictionTestCache(t, 1<<30)
@@ -190,9 +275,9 @@ func TestStopPendingAccessTimeWrites_WritesPendingAccessTimes(t *testing.T) {
 		cache.touchVariant(testVariantKeyOne)
 	}
 
-	err := cache.StopPendingAccessTimeWrites(t.Context())
+	err := cache.StopPendingCountWrites(t.Context())
 	if err != nil {
-		t.Fatalf("StopPendingAccessTimeWrites() error = %v", err)
+		t.Fatalf("StopPendingCountWrites() error = %v", err)
 	}
 
 	for key, wantTouched := range map[imagerequest.VariantKey]int{

internal/imgcache/cache_internal_test.go

@@ -7,7 +7,6 @@ import (
 	"testing"
 	"time"
 
-	"github.com/prometheus/client_golang/prometheus"
 	_ "modernc.org/sqlite"
 )
 
@@ -23,17 +22,54 @@ func setupTestDB(t *testing.T) *sql.DB {
 	schema := `
 		CREATE TABLE source_content (
 			source_key TEXT PRIMARY KEY,
+			source_host TEXT NOT NULL,
+			source_path TEXT NOT NULL,
+			source_query TEXT NOT NULL DEFAULT '',
+			content_type TEXT NOT NULL,
 			size_bytes INTEGER NOT NULL,
+			fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP,
 			last_accessed_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
 		);
+		CREATE TABLE output_content (
+			content_hash TEXT PRIMARY KEY,
+			content_type TEXT NOT NULL,
+			size_bytes INTEGER NOT NULL,
+			fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP
+		);
+		CREATE TABLE request_cache (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			cache_key TEXT NOT NULL UNIQUE,
+			source_metadata_id INTEGER NOT NULL,
+			output_hash TEXT NOT NULL,
+			width INTEGER NOT NULL,
+			height INTEGER NOT NULL,
+			format TEXT NOT NULL,
+			quality INTEGER NOT NULL DEFAULT 85,
+			fit_mode TEXT NOT NULL DEFAULT 'cover',
+			fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+			access_count INTEGER NOT NULL DEFAULT 1
+		);
 		CREATE TABLE negative_cache (
 			id INTEGER PRIMARY KEY AUTOINCREMENT,
 			source_host TEXT NOT NULL,
 			source_path TEXT NOT NULL,
 			source_query TEXT NOT NULL DEFAULT '',
+			status_code INTEGER NOT NULL,
+			error_message TEXT,
+			fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP,
 			expires_at DATETIME NOT NULL,
 			UNIQUE(source_host, source_path, source_query)
 		);
+		CREATE TABLE cache_stats (
+			id INTEGER PRIMARY KEY CHECK (id = 1),
+			hit_count INTEGER NOT NULL DEFAULT 0,
+			miss_count INTEGER NOT NULL DEFAULT 0,
+			upstream_fetch_count INTEGER NOT NULL DEFAULT 0,
+			upstream_fetch_bytes INTEGER NOT NULL DEFAULT 0,
+			transform_count INTEGER NOT NULL DEFAULT 0,
+			last_updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
+		);
+		INSERT INTO cache_stats (id) VALUES (1);
 	`
 
 	_, err = db.ExecContext(t.Context(), schema)
@@ -44,25 +80,66 @@ func setupTestDB(t *testing.T) *sql.DB {
 	return db
 }
 
+func setupTestCache(t *testing.T) *Cache {
+	t.Helper()
+
+	tmpDir := t.TempDir()
+	db := setupTestDB(t)
+
+	cache, err := NewCache(db, CacheConfig{
+		StateDir:    tmpDir,
+		NegativeTTL: 5 * time.Minute,
+	})
+	if err != nil {
+		t.Fatalf("failed to create cache: %v", err)
+	}
+
+	return cache
+}
+
+func TestCache_Stats(t *testing.T) {
+	t.Parallel()
+
+	cache := setupTestCache(t)
+	ctx := context.Background()
+
+	// Increment some stats
+	cache.IncrementStats(true, 0)
+	cache.IncrementStats(true, 0)
+	cache.IncrementStats(false, 1024)
+
+	stats, err := cache.Stats(ctx)
+	if err != nil {
+		t.Fatalf("Stats() error = %v", err)
+	}
+
+	if stats.HitCount != 2 {
+		t.Errorf("Stats() HitCount = %d, want 2", stats.HitCount)
+	}
+
+	if stats.MissCount != 1 {
+		t.Errorf("Stats() MissCount = %d, want 1", stats.MissCount)
+	}
+}
+
 func TestCache_CleanExpired(t *testing.T) {
 	t.Parallel()
 
 	tmpDir := t.TempDir()
 	db := setupTestDB(t)
 
-	cache, _ := NewCache(db, Config{
+	cache, _ := NewCache(db, CacheConfig{
 		StateDir:    tmpDir,
 		NegativeTTL: 1 * time.Millisecond,
-		MaxBytes:    1 << 30,
-	}, prometheus.NewRegistry())
+	})
 
 	ctx := context.Background()
 
 	// Insert expired negative cache entry directly
 	_, err := db.ExecContext(ctx, `
 		INSERT INTO negative_cache
-			(source_host, source_path, source_query, expires_at)
-		VALUES ('example.com', '/old.jpg', '', datetime('now', '-1 hour'))
+			(source_host, source_path, source_query, status_code, expires_at)
+		VALUES ('example.com', '/old.jpg', '', 404, datetime('now', '-1 hour'))
 	`)
 	if err != nil {
 		t.Fatalf("failed to insert test data: %v", err)
@@ -103,10 +180,9 @@ func TestCache_StorageDirectoriesCreated(t *testing.T) {
 	tmpDir := t.TempDir()
 	db := setupTestDB(t)
 
-	_, err := NewCache(db, Config{
+	_, err := NewCache(db, CacheConfig{
 		StateDir: tmpDir,
-		MaxBytes: 1 << 30,
-	}, prometheus.NewRegistry())
+	})
 	if err != nil {
 		t.Fatalf("NewCache() error = %v", err)
 	}

internal/imgcache/cachesize.go

@@ -0,0 +1,85 @@
+package imgcache
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"math"
+	"path/filepath"
+	"syscall"
+)
+
+// DefaultCacheMaxBytesFloor is the minimum computed default for the
+// cache_max_bytes setting: 500 MiB. The floor applies only to the
+// computed default (when the key is omitted from the configuration),
+// never to explicitly configured values.
+const DefaultCacheMaxBytesFloor int64 = 524288000
+
+// freeSpaceFractionNumerator and freeSpaceFractionDenominator express
+// the 75% share used for the computed default limit as integer
+// arithmetic (dividing before multiplying avoids overflow).
+const (
+	freeSpaceFractionNumerator   uint64 = 3
+	freeSpaceFractionDenominator uint64 = 4
+)
+
+var errNegativeBlockSize = errors.New("statfs reported negative block size")
+
+// FreeSpaceProbeFunc reports the number of free bytes available on the
+// filesystem containing path. It is a function type so tests can
+// inject a fake probe instead of depending on the host disk.
+type FreeSpaceProbeFunc func(path string) (uint64, error)
+
+// defaultFreeSpaceProbe reports free filesystem bytes via statfs on
+// the given path, as available to unprivileged processes.
+func defaultFreeSpaceProbe(path string) (uint64, error) {
+	var stat syscall.Statfs_t
+
+	err := syscall.Statfs(path, &stat)
+	if err != nil {
+		return 0, err
+	}
+
+	if stat.Bsize < 0 {
+		return 0, fmt.Errorf("%w %d for %q", errNegativeBlockSize, stat.Bsize, path)
+	}
+
+	blockSize := uint64(stat.Bsize)
+
+	return stat.Bavail * blockSize, nil
+}
+
+// computeDefaultMaxBytes returns the default cache size limit: 75% of
+// the sum of the free bytes probe reports for <state_dir>/cache/ and
+// the bytes the cache already holds, with a floor of
+// DefaultCacheMaxBytesFloor. Counting what the cache holds keeps the
+// limit from shrinking as the cache fills.
+func (c *Cache) computeDefaultMaxBytes(
+	ctx context.Context, probe FreeSpaceProbeFunc,
+) (int64, error) {
+	cacheDir := filepath.Join(c.config.StateDir, "cache")
+
+	freeBytes, err := probe(cacheDir)
+	if err != nil {
+		return 0, fmt.Errorf(
+			"default cache_max_bytes: cannot determine free space for %q: %w",
+			cacheDir, err)
+	}
+
+	usedBytes, err := c.UsageBytes(ctx)
+	if err != nil {
+		return 0, err
+	}
+
+	// Both terms are at most math.MaxInt64, so the sum cannot overflow.
+	//nolint:gosec // G115: UsageBytes returns the total cache usage, never negative
+	spaceBytes := min(freeBytes, math.MaxInt64) + uint64(usedBytes)
+
+	computed := spaceBytes / freeSpaceFractionDenominator * freeSpaceFractionNumerator
+	computed = min(computed, math.MaxInt64)
+
+	limit := int64(computed)
+	limit = max(limit, DefaultCacheMaxBytesFloor)
+
+	return limit, nil
+}

internal/imgcache/cachesize_internal_test.go

@@ -0,0 +1,188 @@
+package imgcache
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// Static errors returned by the stub free-space probes below.
+var (
+	errTestStatfsFailed     = errors.New("statfs failed")
+	errTestProbeNotExpected = errors.New("probe must not be called")
+)
+
+// TestComputeDefaultMaxBytesCountsWhatTheCacheHolds verifies that the
+// default limit is 75% of the free space plus what the cache already
+// holds, so a cache filled to its limit keeps that limit across a
+// restart instead of shrinking to 75% of the space left free.
+func TestComputeDefaultMaxBytesCountsWhatTheCacheHolds(t *testing.T) {
+	t.Parallel()
+
+	cache, _ := newEvictionTestCache(t, 1<<30)
+
+	// Empty cache, 4 GiB free -> 3 GiB default.
+	got, err := cache.computeDefaultMaxBytes(t.Context(),
+		func(string) (uint64, error) { return 4294967296, nil })
+	if err != nil {
+		t.Fatalf("computeDefaultMaxBytes returned error: %v", err)
+	}
+
+	t.Logf("default for an empty cache with 4 GiB free: %d", got)
+
+	if got != 3221225472 {
+		t.Errorf("default for an empty cache = %d, want 3221225472 (75%% of 4 GiB)",
+			got)
+	}
+
+	// The cache now holds those 3 GiB, which leaves 1 GiB free.
+	_, err = cache.db.ExecContext(t.Context(),
+		`INSERT INTO variant_content (cache_key, size_bytes, content_type)
+		 VALUES (?, ?, ?)`,
+		string(testVariantKeyOne), 3221225472, testContentTypeWebP,
+	)
+	if err != nil {
+		t.Fatalf("failed to insert variant accounting row: %v", err)
+	}
+
+	got, err = cache.computeDefaultMaxBytes(t.Context(),
+		func(string) (uint64, error) { return 1073741824, nil })
+	if err != nil {
+		t.Fatalf("computeDefaultMaxBytes returned error: %v", err)
+	}
+
+	t.Logf("default for a cache holding 3 GiB with 1 GiB free: %d", got)
+
+	if got != 3221225472 {
+		t.Errorf("default for a cache holding 3 GiB with 1 GiB free = %d, "+
+			"want 3221225472 (75%% of 1 GiB + 3 GiB)", got)
+	}
+}
+
+// TestComputeDefaultMaxBytesAppliesFloor verifies that when 75% of the
+// free space plus what the cache holds is below 500 MiB, the default
+// is floored at DefaultCacheMaxBytesFloor.
+func TestComputeDefaultMaxBytesAppliesFloor(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name      string
+		freeBytes uint64
+	}{
+		{name: "100 MiB free", freeBytes: 104857600},
+		{name: "zero free", freeBytes: 0},
+		{name: "just below floor threshold", freeBytes: 699050665},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			cache, _ := newEvictionTestCache(t, 1<<30)
+
+			got, err := cache.computeDefaultMaxBytes(t.Context(),
+				func(string) (uint64, error) { return tc.freeBytes, nil })
+			if err != nil {
+				t.Fatalf("computeDefaultMaxBytes returned error: %v", err)
+			}
+
+			if got != DefaultCacheMaxBytesFloor {
+				t.Errorf("computeDefaultMaxBytes = %d, want floor %d",
+					got, DefaultCacheMaxBytesFloor)
+			}
+		})
+	}
+}
+
+// TestComputeDefaultMaxBytesPropagatesProbeError verifies that a
+// failing free-space probe produces an error naming cache_max_bytes,
+// instead of a silently wrong default.
+func TestComputeDefaultMaxBytesPropagatesProbeError(t *testing.T) {
+	t.Parallel()
+
+	cache, _ := newEvictionTestCache(t, 1<<30)
+
+	_, err := cache.computeDefaultMaxBytes(t.Context(),
+		func(string) (uint64, error) { return 0, errTestStatfsFailed })
+	if err == nil {
+		t.Fatal("probe failure must produce an error, got nil")
+	}
+
+	t.Logf("got expected error: %v", err)
+
+	if !strings.Contains(err.Error(), "cache_max_bytes") {
+		t.Errorf("error %q does not name cache_max_bytes", err.Error())
+	}
+}
+
+// TestNewCacheComputesDefaultMaxBytesWhenAsked verifies that with
+// UseDefaultMaxBytes set, the cache's limit becomes the computed
+// default, and that the probe is pointed at <state_dir>/cache/, which
+// must be created first so statfs measures the right filesystem.
+func TestNewCacheComputesDefaultMaxBytesWhenAsked(t *testing.T) {
+	t.Parallel()
+
+	stateDir := t.TempDir()
+	wantCacheDir := filepath.Join(stateDir, "cache")
+
+	var probedPath string
+
+	// 4 GiB free -> 3 GiB default.
+	probe := func(path string) (uint64, error) {
+		probedPath = path
+
+		info, err := os.Stat(path)
+		if err != nil || !info.IsDir() {
+			t.Errorf("cache directory %q was not created before probing: info=%v err=%v",
+				path, info, err)
+		}
+
+		return 4294967296, nil
+	}
+
+	cache, err := newCache(evictionTestDB(t), CacheConfig{
+		StateDir:           stateDir,
+		UseDefaultMaxBytes: true,
+	}, probe)
+	if err != nil {
+		t.Fatalf("newCache returned error: %v", err)
+	}
+
+	if cache.config.MaxBytes != 3221225472 {
+		t.Errorf("MaxBytes = %d, want computed default 3221225472",
+			cache.config.MaxBytes)
+	}
+
+	if probedPath != wantCacheDir {
+		t.Errorf("free space probed at %q, want cache directory %q",
+			probedPath, wantCacheDir)
+	}
+}
+
+// TestNewCacheKeepsExplicitMaxBytes verifies that without
+// UseDefaultMaxBytes the cache keeps MaxBytes exactly as given and
+// never consults the free-space probe.
+func TestNewCacheKeepsExplicitMaxBytes(t *testing.T) {
+	t.Parallel()
+
+	probe := func(string) (uint64, error) {
+		t.Error("free-space probe must not be consulted for explicit values")
+
+		return 0, errTestProbeNotExpected
+	}
+
+	cache, err := newCache(evictionTestDB(t), CacheConfig{
+		StateDir: t.TempDir(),
+		MaxBytes: 1024,
+	}, probe)
+	if err != nil {
+		t.Fatalf("newCache returned error: %v", err)
+	}
+
+	if cache.config.MaxBytes != 1024 {
+		t.Errorf("MaxBytes = %d, want explicit 1024 (no floor, no recompute)",
+			cache.config.MaxBytes)
+	}
+}

internal/imgcache/concurrent_misses_internal_test.go

@@ -1,4 +1,4 @@
-package imageproxy
+package imgcache
 
 import (
 	"bytes"
@@ -36,7 +36,7 @@ type heldFetcher struct {
 }
 
 func (f *heldFetcher) Fetch(
-	ctx context.Context, source imagerequest.Source,
+	ctx context.Context, url string,
 ) (*httpfetcher.FetchResult, error) {
 	f.fetches.Add(1)
 
@@ -48,7 +48,7 @@ func (f *heldFetcher) Fetch(
 		return nil, ctx.Err()
 	}
 
-	return f.upstream.Fetch(ctx, source)
+	return f.upstream.Fetch(ctx, url)
 }
 
 // releaseFetches lets every held fetch, and every later one, go on.
@@ -56,15 +56,15 @@ func (f *heldFetcher) releaseFetches() {
 	f.releaseOnce.Do(func() { close(f.release) })
 }
 
-// setupHeldFetchProxy returns a test proxy whose fetches go through a
+// setupHeldFetchService returns a test service whose fetches go through a
 // heldFetcher. Its database is limited to one connection: each connection to
 // an in-memory SQLite database opens a new, empty one, so requests running at
 // once must share the connection that holds the schema.
-func setupHeldFetchProxy(t *testing.T) (*testProxy, *TestFixtures, *heldFetcher) {
+func setupHeldFetchService(t *testing.T) (*Service, *TestFixtures, *heldFetcher) {
 	t.Helper()
 
-	svc, fixtures := setupTestProxy(t)
-	svc.db.SetMaxOpenConns(1)
+	svc, fixtures := SetupTestService(t)
+	svc.cache.db.SetMaxOpenConns(1)
 
 	fetcher := &heldFetcher{
 		upstream: svc.fetcher,
@@ -79,8 +79,8 @@ func setupHeldFetchProxy(t *testing.T) (*testProxy, *TestFixtures, *heldFetcher)
 }
 
 // photoVariant asks for the test photo, 100x100, at 50x25 as a JPEG of the
-// given quality and fit mode. Each call returns a new request, which a test
-// may change.
+// given quality and fit mode. Each call returns a new request, as Get writes
+// to the request it is given.
 func photoVariant(
 	fixtures *TestFixtures, quality int, fit imagerequest.Fit,
 ) *imagerequest.Request {
@@ -107,7 +107,7 @@ type getResult struct {
 // startGet calls Get in a goroutine of its own and delivers what it returned
 // on the channel.
 func startGet(
-	ctx context.Context, svc *testProxy, req *imagerequest.Request,
+	ctx context.Context, svc *Service, req *imagerequest.Request,
 ) <-chan getResult {
 	results := make(chan getResult, 1)
 
@@ -139,14 +139,14 @@ func jpegSize(data []byte) (int, int) {
 	return config.Width, config.Height
 }
 
-// TestProxy_Get_ConcurrentMissesShareOneFetch starts several requests for
+// TestService_Get_ConcurrentMissesShareOneFetch starts several requests for
 // one uncached variant while the first one's fetch is held. Between them they
 // must fetch the source once and transcode it once, every one must be answered
 // with the same 50x25 JPEG, and each must count one miss.
-func TestProxy_Get_ConcurrentMissesShareOneFetch(t *testing.T) {
+func TestService_Get_ConcurrentMissesShareOneFetch(t *testing.T) {
 	t.Parallel()
 
-	svc, fixtures, fetcher := setupHeldFetchProxy(t)
+	svc, fixtures, fetcher := setupHeldFetchService(t)
 
 	const requests = 8
 
@@ -183,7 +183,7 @@ func TestProxy_Get_ConcurrentMissesShareOneFetch(t *testing.T) {
 		t.Errorf("%d requests made %d upstream fetches, want 1", requests, fetches)
 	}
 
-	// NewTestFS builds the same files the test proxy's fetcher serves.
+	// NewTestFS builds the same files the test service's fetcher serves.
 	testFS, _ := NewTestFS(t)
 
 	photo, err := fs.ReadFile(testFS, fixtures.GoodHostJPEG)
@@ -191,20 +191,22 @@ func TestProxy_Get_ConcurrentMissesShareOneFetch(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	want := counterValues{0, requests, 1, int64(len(photo)), 1}
+	want := cacheStatsCounters{0, requests, 1, int64(len(photo)), 1}
 
-	if got := readCounters(t, svc); got != want {
+	waitForPendingCountsWritten(t, svc.cache)
+
+	if got := readCacheStatsCounters(t, svc.cache); got != want {
 		t.Errorf("counters = %+v, want %+v", got, want)
 	}
 }
 
-// TestProxy_Get_ConcurrentVariantsStayApart requests three variants of the
+// TestService_Get_ConcurrentVariantsStayApart requests three variants of the
 // test photo at once that differ only in quality or fit. Each must be made by
 // a fetch and a transcode of its own, and each answer must be its own variant.
-func TestProxy_Get_ConcurrentVariantsStayApart(t *testing.T) {
+func TestService_Get_ConcurrentVariantsStayApart(t *testing.T) {
 	t.Parallel()
 
-	svc, fixtures, fetcher := setupHeldFetchProxy(t)
+	svc, fixtures, fetcher := setupHeldFetchService(t)
 
 	cover := startGet(t.Context(), svc, photoVariant(fixtures, 85, imagerequest.FitCover))
 	lowQuality := startGet(t.Context(), svc,
@@ -253,14 +255,14 @@ func TestProxy_Get_ConcurrentVariantsStayApart(t *testing.T) {
 	}
 }
 
-// TestProxy_Get_WaiterStopsWhenItsContextEnds has a second request for a
+// TestService_Get_WaiterStopsWhenItsContextEnds has a second request for a
 // variant join the first one's held fetch, then ends the second request's
 // context. The second request must return at once with the context's error,
 // while the fetch is still held, and the first must still be answered.
-func TestProxy_Get_WaiterStopsWhenItsContextEnds(t *testing.T) {
+func TestService_Get_WaiterStopsWhenItsContextEnds(t *testing.T) {
 	t.Parallel()
 
-	svc, fixtures, fetcher := setupHeldFetchProxy(t)
+	svc, fixtures, fetcher := setupHeldFetchService(t)
 
 	first := startGet(t.Context(), svc, photoVariant(fixtures, 85, imagerequest.FitCover))
 
@@ -298,15 +300,15 @@ func TestProxy_Get_WaiterStopsWhenItsContextEnds(t *testing.T) {
 	}
 }
 
-// TestProxy_Get_FirstRequestLeavingKeepsTheWork ends the context of the
+// TestService_Get_FirstRequestLeavingKeepsTheWork ends the context of the
 // request whose fetch is held, after a second request has joined it. The fetch
 // and transcode must go on and answer the second request. The first request
 // waits for its own work, as every request did before misses were shared, and
 // is answered too.
-func TestProxy_Get_FirstRequestLeavingKeepsTheWork(t *testing.T) {
+func TestService_Get_FirstRequestLeavingKeepsTheWork(t *testing.T) {
 	t.Parallel()
 
-	svc, fixtures, fetcher := setupHeldFetchProxy(t)
+	svc, fixtures, fetcher := setupHeldFetchService(t)
 
 	firstCtx, cancelFirst := context.WithCancel(t.Context())
 	first := startGet(firstCtx, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
@@ -337,11 +339,11 @@ func TestProxy_Get_FirstRequestLeavingKeepsTheWork(t *testing.T) {
 	}
 }
 
-// TestProxy_Get_ConcurrentMissesShareAFailure has several requests for an
+// TestService_Get_ConcurrentMissesShareAFailure has several requests for an
 // image that cannot be served arrive while its fetch is held: the one fetch
 // answers all of them with its error. The request after them is answered from
 // the negative cache, where the failure is kept.
-func TestProxy_Get_ConcurrentMissesShareAFailure(t *testing.T) {
+func TestService_Get_ConcurrentMissesShareAFailure(t *testing.T) {
 	t.Parallel()
 
 	tests := []struct {
@@ -362,7 +364,7 @@ func TestProxy_Get_ConcurrentMissesShareAFailure(t *testing.T) {
 		t.Run(tc.name, func(t *testing.T) {
 			t.Parallel()
 
-			svc, fixtures, fetcher := setupHeldFetchProxy(t)
+			svc, fixtures, fetcher := setupHeldFetchService(t)
 
 			request := func() *imagerequest.Request {
 				req := photoVariant(fixtures, 85, imagerequest.FitCover)
@@ -398,12 +400,12 @@ func TestProxy_Get_ConcurrentMissesShareAFailure(t *testing.T) {
 	}
 }
 
-// TestProxy_Get_EndedRequestFetchesNothing checks that a request whose
+// TestService_Get_EndedRequestFetchesNothing checks that a request whose
 // context has already ended when it misses the cache starts no fetch.
-func TestProxy_Get_EndedRequestFetchesNothing(t *testing.T) {
+func TestService_Get_EndedRequestFetchesNothing(t *testing.T) {
 	t.Parallel()
 
-	svc, fixtures, fetcher := setupHeldFetchProxy(t)
+	svc, fixtures, fetcher := setupHeldFetchService(t)
 
 	ctx, cancel := context.WithCancel(t.Context())
 	cancel()
@@ -418,14 +420,14 @@ func TestProxy_Get_EndedRequestFetchesNothing(t *testing.T) {
 	}
 }
 
-// TestProxy_Get_ReturnsByItsDeadline gives a request a deadline and holds
+// TestService_Get_ReturnsByItsDeadline gives a request a deadline and holds
 // its fetch until the fetch's context ends, as the fetcher does while it waits
 // for a free connection to the host. The request must return by its deadline
 // with the deadline's error.
-func TestProxy_Get_ReturnsByItsDeadline(t *testing.T) {
+func TestService_Get_ReturnsByItsDeadline(t *testing.T) {
 	t.Parallel()
 
-	svc, fixtures, _ := setupHeldFetchProxy(t)
+	svc, fixtures, _ := setupHeldFetchService(t)
 
 	const timeout = 200 * time.Millisecond
 
@@ -444,18 +446,18 @@ func TestProxy_Get_ReturnsByItsDeadline(t *testing.T) {
 	}
 }
 
-// TestProxy_Get_WaiterGetsProcessingTimedOut has a request with no deadline
+// TestService_Get_WaiterGetsProcessingTimedOut has a request with no deadline
 // join the held fetch of a first request with a short one. With the only
 // processing slot held, the first request's transcode waits for it until the
 // first request's deadline ends, and stops then. The waiting request, whose
 // own context has not ended, must get ErrProcessingTimedOut, which the image
 // routes answer 503 as when pixa is busy.
-func TestProxy_Get_WaiterGetsProcessingTimedOut(t *testing.T) {
+func TestService_Get_WaiterGetsProcessingTimedOut(t *testing.T) {
 	t.Parallel()
 
-	svc, fixtures, fetcher := setupHeldFetchProxy(t)
+	svc, fixtures, fetcher := setupHeldFetchService(t)
 	svc.processor = imageprocessor.New(
-		imageprocessor.Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1},
+		imageprocessor.Params{MaxConcurrentProcessing: 1},
 	)
 
 	holdProcessingSlot(t, svc.processor)
@@ -489,18 +491,18 @@ func TestProxy_Get_WaiterGetsProcessingTimedOut(t *testing.T) {
 type panickingFetcher struct{}
 
 func (panickingFetcher) Fetch(
-	context.Context, imagerequest.Source,
+	context.Context, string,
 ) (*httpfetcher.FetchResult, error) {
 	panic("upstream fetcher panicked")
 }
 
-// TestProxy_Get_PanicBecomesAnError checks that a panic while a variant is
+// TestService_Get_PanicBecomesAnError checks that a panic while a variant is
 // being made reaches its request as an error naming the panic, instead of
 // being raised again.
-func TestProxy_Get_PanicBecomesAnError(t *testing.T) {
+func TestService_Get_PanicBecomesAnError(t *testing.T) {
 	t.Parallel()
 
-	svc, fixtures := setupTestProxy(t)
+	svc, fixtures := SetupTestService(t)
 	svc.fetcher = panickingFetcher{}
 
 	var err error
@@ -520,13 +522,13 @@ func TestProxy_Get_PanicBecomesAnError(t *testing.T) {
 	}
 }
 
-// TestProxy_Get_PanicIsReportedToSentry checks that a panic while a variant
+// TestService_Get_PanicIsReportedToSentry checks that a panic while a variant
 // is being made is reported through the Sentry hub on the request's context,
 // where the Sentry middleware puts one when sentry_dsn is set.
-func TestProxy_Get_PanicIsReportedToSentry(t *testing.T) {
+func TestService_Get_PanicIsReportedToSentry(t *testing.T) {
 	t.Parallel()
 
-	svc, fixtures := setupTestProxy(t)
+	svc, fixtures := SetupTestService(t)
 	svc.fetcher = panickingFetcher{}
 
 	transport := &sentry.MockTransport{}

internal/imgcache/counters.go

@@ -1,31 +0,0 @@
-package imgcache
-
-import (
-	"fmt"
-
-	"github.com/prometheus/client_golang/prometheus"
-)
-
-// registerCounters makes the cache's counters and registers them on
-// metricsRegistry. The counters are kept in memory, so adding to one waits
-// for nothing and makes no database call. It fails when metricsRegistry
-// already holds counters of the same names.
-func (c *Cache) registerCounters(metricsRegistry prometheus.Registerer) error {
-	c.cacheHits = prometheus.NewCounter(prometheus.CounterOpts{
-		Name: "pixa_cache_hits_total",
-		Help: "Image requests served from the cache.",
-	})
-	c.cacheMisses = prometheus.NewCounter(prometheus.CounterOpts{
-		Name: "pixa_cache_misses_total",
-		Help: "Image requests not served from the cache.",
-	})
-
-	for _, counter := range []prometheus.Counter{c.cacheHits, c.cacheMisses} {
-		err := metricsRegistry.Register(counter)
-		if err != nil {
-			return fmt.Errorf("failed to register the cache's counters: %w", err)
-		}
-	}
-
-	return nil
-}

internal/imgcache/counters_internal_test.go

@@ -1,64 +0,0 @@
-package imgcache
-
-import (
-	"errors"
-	"testing"
-
-	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/testutil"
-)
-
-// TestNewCache_RegistersItsCountersOnItsRegistry checks that NewCache
-// registers the cache's counters on the registry it is given, under the
-// names README.md gives them.
-func TestNewCache_RegistersItsCountersOnItsRegistry(t *testing.T) {
-	t.Parallel()
-
-	registry := prometheus.NewRegistry()
-
-	_, err := NewCache(evictionTestDB(t),
-		Config{StateDir: t.TempDir(), MaxBytes: 1 << 30}, registry)
-	if err != nil {
-		t.Fatalf("NewCache() error = %v", err)
-	}
-
-	names := []string{
-		"pixa_cache_hits_total",
-		"pixa_cache_misses_total",
-	}
-
-	count, err := testutil.GatherAndCount(registry, names...)
-	if err != nil {
-		t.Fatalf("testutil.GatherAndCount() error = %v", err)
-	}
-
-	if count != len(names) {
-		t.Errorf("%d of the counters %v are on the registry, want %d",
-			count, names, len(names))
-	}
-}
-
-// TestNewCache_FailsWhenItsCountersCannotBeRegistered makes a second cache
-// on the registry of a first. Its counters have the same names, so the
-// registry refuses them, and NewCache must return that error.
-func TestNewCache_FailsWhenItsCountersCannotBeRegistered(t *testing.T) {
-	t.Parallel()
-
-	registry := prometheus.NewRegistry()
-
-	_, err := NewCache(evictionTestDB(t),
-		Config{StateDir: t.TempDir(), MaxBytes: 1 << 30}, registry)
-	if err != nil {
-		t.Fatalf("NewCache() of the first cache error = %v", err)
-	}
-
-	_, err = NewCache(evictionTestDB(t),
-		Config{StateDir: t.TempDir(), MaxBytes: 1 << 30}, registry)
-	t.Logf("NewCache() of the second cache error = %v", err)
-
-	var alreadyRegistered prometheus.AlreadyRegisteredError
-	if !errors.As(err, &alreadyRegistered) {
-		t.Errorf("NewCache() of the second cache error = %v, want %T",
-			err, alreadyRegistered)
-	}
-}

internal/imgcache/divzero_internal_test.go

@@ -1,4 +1,4 @@
-package imageproxy
+package imgcache
 
 import (
 	"fmt"

internal/imgcache/eviction.go

@@ -48,29 +48,27 @@ const staleTempFileAge = time.Hour
 const sqliteTimestampLayout = "2006-01-02 15:04:05"
 
 // tempFilePrefix is the prefix os.CreateTemp uses for in-flight cache
-// writes (the ".tmp-*" pattern in writeFileSynced).
+// writes (".tmp-*" patterns in the storage layer).
 const tempFilePrefix = ".tmp-"
 
+// fallbackContentType is the content type reconciliation records for a
+// variant file it adopts whose first bytes are not those of an output
+// format. Such a file is never served.
+const fallbackContentType = "application/octet-stream"
+
 // UsageBytes returns the total number of bytes of cache content
-// tracked in the database, as the package function UsageBytes does, or 0
-// when the disk cache is off.
+// tracked in the database (source content blobs plus processed
+// variants). It reads the total the database keeps up to date as rows
+// are added and removed, so it neither scans the cache directories nor
+// sums the tables.
 func (c *Cache) UsageBytes(ctx context.Context) (int64, error) {
-	if c.config.MaxBytes == 0 {
+	if c.disabled {
 		return 0, nil
 	}
 
-	return UsageBytes(ctx, c.db)
-}
-
-// UsageBytes returns the total number of bytes of cache content tracked
-// in db (source content blobs plus processed variants). It reads the
-// total the database keeps up to date as rows are added and removed, so
-// it neither scans the cache directories nor sums the tables. pixad reads
-// it before it builds the cache, to work out the default cache_max_bytes.
-func UsageBytes(ctx context.Context, db *sql.DB) (int64, error) {
 	var total int64
 
-	err := db.QueryRowContext(ctx,
+	err := c.db.QueryRowContext(ctx,
 		`SELECT total_size_bytes FROM cache_usage WHERE id = 1`,
 	).Scan(&total)
 	if err != nil {
@@ -93,9 +91,9 @@ type evictionCandidate struct {
 
 // EvictToLimit evicts least-recently-used cache entries until total
 // tracked usage is at or below the configured MaxBytes limit. It is a
-// no-op when the cache is disabled.
+// no-op when the cache is disabled or no limit is configured.
 func (c *Cache) EvictToLimit(ctx context.Context) error {
-	if c.config.MaxBytes == 0 {
+	if c.disabled || c.config.MaxBytes <= 0 {
 		return nil
 	}
 
@@ -306,7 +304,7 @@ func (c *Cache) evictVariant(
 		return fmt.Errorf("failed to delete variant accounting row: %w", err)
 	}
 
-	err = c.variants.Delete(string(cacheKey))
+	err = c.variants.Delete(cacheKey)
 	if err != nil {
 		return err
 	}
@@ -317,7 +315,7 @@ func (c *Cache) evictVariant(
 // evictSourceBlob removes one source: its row first, then its file, as
 // evictVariant does for a variant. It holds no lock: a store of the same
 // source in between can leave the source's row with no file, which
-// Source treats as a miss.
+// LookupSource treats as a miss.
 func (c *Cache) evictSourceBlob(ctx context.Context, key imagerequest.SourceKey) error {
 	_, err := c.db.ExecContext(ctx,
 		`DELETE FROM source_content WHERE source_key = ?`, string(key))
@@ -325,7 +323,7 @@ func (c *Cache) evictSourceBlob(ctx context.Context, key imagerequest.SourceKey)
 		return fmt.Errorf("failed to delete source content row: %w", err)
 	}
 
-	return c.srcContent.Delete(string(key))
+	return c.srcContent.Delete(key)
 }
 
 // notifyWritePressure wakes the background evictor after a store, so
@@ -333,7 +331,7 @@ func (c *Cache) evictSourceBlob(ctx context.Context, key imagerequest.SourceKey)
 // storing request. The notification channel has capacity one and drops
 // when a wakeup is already pending.
 func (c *Cache) notifyWritePressure() {
-	if c.config.MaxBytes == 0 {
+	if c.disabled || c.config.MaxBytes <= 0 {
 		return
 	}
 
@@ -479,7 +477,7 @@ func (c *Cache) runCleanExpired(ctx context.Context) {
 // then on the first periodic eviction tick that comes at least ten times
 // as long after the last pass ended as that pass took, off the request
 // hot path: it adopts variant files that predate the accounting table
-// (or whose accounting insert failed, e.g. PutVariant's best-effort
+// (or whose accounting insert failed, e.g. StoreVariant's best-effort
 // insert under transient DB contention), drops variant accounting rows
 // whose files are missing, removes source blob files the database does
 // not know, removes source and variant files that are empty or not the
@@ -492,7 +490,7 @@ func (c *Cache) runCleanExpired(ctx context.Context) {
 // Once ctx is cancelled, it stops at the next file or row and returns
 // ctx's error.
 func (c *Cache) reconcileAccounting(ctx context.Context) error {
-	if c.config.MaxBytes == 0 {
+	if c.disabled {
 		return nil
 	}
 
@@ -514,81 +512,50 @@ func (c *Cache) reconcileAccounting(ctx context.Context) error {
 	return c.reconcileUsageTotal(ctx)
 }
 
-// reconcileFiles walks baseDir, one of the cache's storage directories,
-// sweeping stale temp files and passing each other file, with its info and
-// name, to reconcileFile. It skips a directory it cannot list and a file
-// whose info it cannot read, so one such entry does not stop the pass. It
-// logs a warning naming the path and the error. A file renamed or removed
-// after its directory was listed is skipped with no warning. Once ctx is
-// cancelled it stops at the next file and returns ctx's error.
-func (c *Cache) reconcileFiles(
-	ctx context.Context, baseDir string,
-	reconcileFile func(path string, info fs.FileInfo, name string) error,
-) error {
+// reconcileVariantFiles walks the variant storage directory, checking
+// each variant file against its accounting row (reconcileVariantFile)
+// and sweeping stale temp files.
+func (c *Cache) reconcileVariantFiles(ctx context.Context) error {
 	return filepath.WalkDir(
-		baseDir,
+		c.variants.baseDir,
 		func(path string, entry fs.DirEntry, err error) error {
 			if ctx.Err() != nil {
 				return ctx.Err()
 			}
 
-			if err != nil {
-				c.log.Warn("skipped unreadable entry in cache directory",
-					"path", path, "error", err)
-
-				return nil
-			}
-
-			if entry.IsDir() {
-				return nil
-			}
-
-			info, err := entry.Info()
-			if errors.Is(err, fs.ErrNotExist) {
-				return nil
-			}
-
-			if err != nil {
-				c.log.Warn("skipped unreadable entry in cache directory",
-					"path", path, "error", err)
-
-				return nil
+			if err != nil || entry.IsDir() {
+				return err
 			}
 
 			name := entry.Name()
 
 			if strings.HasPrefix(name, tempFilePrefix) {
-				c.sweepStaleTempFile(path, info)
+				c.sweepStaleTempFile(path, entry)
 
 				return nil
 			}
 
-			return reconcileFile(path, info, name)
+			return c.reconcileVariantFile(ctx, path, entry, imagerequest.VariantKey(name))
 		},
 	)
 }
 
-// reconcileVariantFiles walks the variant storage directory, checking
-// each variant file against its accounting row (reconcileVariantFile)
-// and sweeping stale temp files.
-func (c *Cache) reconcileVariantFiles(ctx context.Context) error {
-	return c.reconcileFiles(ctx, c.variants.baseDir,
-		func(path string, info fs.FileInfo, name string) error {
-			return c.reconcileVariantFile(ctx, path, info, imagerequest.VariantKey(name))
-		})
-}
-
 // reconcileVariantFile checks one variant file against its accounting
 // row. A file without a row is adopted into the accounting, unless it is
 // empty. A file that is empty, or not the size its row records, as a
 // crash or a restored snapshot can leave it, is removed with its row and
 // a warning naming it, so the variant is converted again.
 func (c *Cache) reconcileVariantFile(
-	ctx context.Context, path string, info fs.FileInfo, cacheKey imagerequest.VariantKey,
+	ctx context.Context, path string, entry fs.DirEntry, cacheKey imagerequest.VariantKey,
 ) error {
+	info, err := entry.Info()
+	if err != nil {
+		return fmt.Errorf("failed to stat variant file: %w", err)
+	}
+
 	var recordedSize int64
 
-	err := c.db.QueryRowContext(ctx,
+	err = c.db.QueryRowContext(ctx,
 		`SELECT size_bytes FROM variant_content WHERE cache_key = ?`, string(cacheKey),
 	).Scan(&recordedSize)
 
@@ -609,16 +576,25 @@ func (c *Cache) reconcileVariantFile(
 }
 
 // adoptVariantFile inserts an accounting row for a variant file that
-// has none, using the file's size and modification time.
+// has none, using the file's size and modification time, and the content
+// type its first bytes show, as a hit reads it.
 func (c *Cache) adoptVariantFile(
 	ctx context.Context, info fs.FileInfo, cacheKey imagerequest.VariantKey,
 ) error {
 	modTime := info.ModTime().UTC().Format(sqliteTimestampLayout)
+	contentType := fallbackContentType
 
-	_, err := c.db.ExecContext(ctx, `
-		INSERT INTO variant_content (cache_key, size_bytes, last_accessed_at)
-		VALUES (?, ?, ?)
-	`, string(cacheKey), info.Size(), modTime)
+	content, _, detectedType, err := c.variants.LoadWithContentType(cacheKey)
+	if err == nil {
+		_ = content.Close()
+		contentType = detectedType
+	}
+
+	_, err = c.db.ExecContext(ctx, `
+		INSERT INTO variant_content
+			(cache_key, size_bytes, content_type, created_at, last_accessed_at)
+		VALUES (?, ?, ?, ?, ?)
+	`, string(cacheKey), info.Size(), contentType, modTime, modTime)
 	if err != nil {
 		return fmt.Errorf("failed to adopt variant file into accounting: %w", err)
 	}
@@ -630,9 +606,7 @@ func (c *Cache) adoptVariantFile(
 }
 
 // reconcileVariantRows drops accounting rows whose variant files are
-// missing, so the database never references deleted content. A file whose
-// size cannot be read for another reason may still be on disk, so its row
-// stays, with a warning naming its key and the error.
+// missing, so the database never references deleted content.
 func (c *Cache) reconcileVariantRows(ctx context.Context) error {
 	var after imagerequest.VariantKey
 
@@ -655,19 +629,11 @@ func (c *Cache) reconcileVariantRows(ctx context.Context) error {
 				return ctx.Err()
 			}
 
-			_, err := c.variants.Size(string(key))
-			if err == nil {
+			if c.variants.Exists(key) {
 				continue
 			}
 
-			if !errors.Is(err, ErrNotFound) {
-				c.log.Warn("kept accounting row for unreadable variant file",
-					"cache_key", key, "error", err)
-
-				continue
-			}
-
-			_, err = c.db.ExecContext(ctx,
+			_, err := c.db.ExecContext(ctx,
 				`DELETE FROM variant_content WHERE cache_key = ?`, string(key))
 			if err != nil {
 				return fmt.Errorf("failed to drop stale variant accounting row: %w", err)
@@ -730,10 +696,28 @@ func queryStringColumn[T ~string](
 // each blob file against its source_content row (reconcileSourceFile)
 // and sweeping stale temp files.
 func (c *Cache) reconcileSourceFiles(ctx context.Context) error {
-	return c.reconcileFiles(ctx, c.srcContent.baseDir,
-		func(path string, info fs.FileInfo, name string) error {
-			return c.reconcileSourceFile(ctx, path, info, imagerequest.SourceKey(name))
-		})
+	return filepath.WalkDir(
+		c.srcContent.baseDir,
+		func(path string, entry fs.DirEntry, err error) error {
+			if ctx.Err() != nil {
+				return ctx.Err()
+			}
+
+			if err != nil || entry.IsDir() {
+				return err
+			}
+
+			name := entry.Name()
+
+			if strings.HasPrefix(name, tempFilePrefix) {
+				c.sweepStaleTempFile(path, entry)
+
+				return nil
+			}
+
+			return c.reconcileSourceFile(ctx, path, entry, imagerequest.SourceKey(name))
+		},
+	)
 }
 
 // reconcileSourceFile checks one source blob file against its
@@ -743,11 +727,16 @@ func (c *Cache) reconcileSourceFiles(ctx context.Context) error {
 // is removed with its row and a warning naming it, so the source is
 // fetched again.
 func (c *Cache) reconcileSourceFile(
-	ctx context.Context, path string, info fs.FileInfo, key imagerequest.SourceKey,
+	ctx context.Context, path string, entry fs.DirEntry, key imagerequest.SourceKey,
 ) error {
+	info, err := entry.Info()
+	if err != nil {
+		return fmt.Errorf("failed to stat source content file: %w", err)
+	}
+
 	var recordedSize int64
 
-	err := c.db.QueryRowContext(ctx,
+	err = c.db.QueryRowContext(ctx,
 		`SELECT size_bytes FROM source_content WHERE source_key = ?`,
 		string(key),
 	).Scan(&recordedSize)
@@ -912,12 +901,17 @@ func (c *Cache) correctUsageTotal(
 
 // sweepStaleTempFile removes a temp file left behind by a crashed
 // write once it is old enough that no in-flight store can own it.
-func (c *Cache) sweepStaleTempFile(path string, info fs.FileInfo) {
+func (c *Cache) sweepStaleTempFile(path string, entry fs.DirEntry) {
+	info, err := entry.Info()
+	if err != nil {
+		return
+	}
+
 	if time.Since(info.ModTime()) < staleTempFileAge {
 		return
 	}
 
-	err := os.Remove(path)
+	err = os.Remove(path)
 	if err != nil && !os.IsNotExist(err) {
 		c.log.Warn("failed to remove stale temp file", "path", path, "error", err)
 

internal/imgcache/eviction_internal_test.go

@@ -9,16 +9,14 @@ import (
 	"log/slog"
 	"os"
 	"path/filepath"
-	"slices"
 	"strings"
 	"sync"
-	"syscall"
 	"testing"
 	"time"
 
-	"github.com/prometheus/client_golang/prometheus"
 	"modernc.org/sqlite"
 	"sneak.berlin/go/pixa/internal/database"
+	"sneak.berlin/go/pixa/internal/httpfetcher"
 	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
@@ -68,12 +66,16 @@ func newEvictionTestCache(t *testing.T, maxBytes int64) (*Cache, string) {
 	tmpDir := t.TempDir()
 	db := evictionTestDB(t)
 
-	// maxBytes zero turns the disk cache off, as cache_max_bytes: 0 does.
-	cache, err := NewCache(db, Config{
-		StateDir:    tmpDir,
-		NegativeTTL: 5 * time.Minute,
-		MaxBytes:    maxBytes,
-	}, prometheus.NewRegistry())
+	// maxBytes zero mirrors the production mapping of
+	// cache_max_bytes: 0 (handlers sets DisableDiskCache); at the
+	// CacheConfig layer itself a zero MaxBytes means "no limit" for
+	// backwards compatibility with existing fixtures.
+	cache, err := NewCache(db, CacheConfig{
+		StateDir:         tmpDir,
+		NegativeTTL:      5 * time.Minute,
+		MaxBytes:         maxBytes,
+		DisableDiskCache: maxBytes == 0,
+	})
 	if err != nil {
 		t.Fatalf("failed to create cache: %v", err)
 	}
@@ -100,11 +102,20 @@ func storeEvictionTestSource(
 		},
 	}
 
-	key, err := cache.PutSource(
-		context.Background(), req.Source, bytes.NewReader(content),
+	result := &httpfetcher.FetchResult{
+		StatusCode:    200,
+		ContentType:   testContentTypeJPEG,
+		ContentLength: int64(len(content)),
+		Headers: map[string][]string{
+			testHeaderContentType: {testContentTypeJPEG},
+		},
+	}
+
+	key, err := cache.StoreSource(
+		context.Background(), req, bytes.NewReader(content), result,
 	)
 	if err != nil {
-		t.Fatalf("PutSource(%s%s) failed: %v", host, path, err)
+		t.Fatalf("StoreSource(%s%s) failed: %v", host, path, err)
 	}
 
 	return key
@@ -117,9 +128,9 @@ func storeEvictionTestVariant(
 ) {
 	t.Helper()
 
-	err := cache.PutVariant(t.Context(), key, bytes.NewReader(content))
+	err := cache.StoreVariant(t.Context(), key, bytes.NewReader(content), "image/webp")
 	if err != nil {
-		t.Fatalf("PutVariant(%s) failed: %v", key, err)
+		t.Fatalf("StoreVariant(%s) failed: %v", key, err)
 	}
 }
 
@@ -211,8 +222,7 @@ func assertNoDanglingReferences(t *testing.T, cache *Cache) {
 			t.Fatalf("failed to scan source_key: %v", err)
 		}
 
-		_, err = os.Stat(cache.srcContent.keyToPath(key))
-		if err != nil {
+		if !cache.srcContent.Exists(imagerequest.SourceKey(key)) {
 			t.Errorf("source_content references content %s but the file is missing",
 				key)
 		}
@@ -239,8 +249,7 @@ func assertNoDanglingReferences(t *testing.T, cache *Cache) {
 			t.Fatalf("failed to scan cache_key: %v", err)
 		}
 
-		_, err = os.Stat(cache.variants.keyToPath(key))
-		if err != nil {
+		if !cache.variants.Exists(imagerequest.VariantKey(key)) {
 			t.Errorf("variant_content references key %s but the file is missing", key)
 		}
 	}
@@ -338,8 +347,7 @@ func TestEvictToLimitEvictsLeastRecentlyUsedFirst(t *testing.T) {
 		t.Errorf("usage after eviction = %d, want <= %d", usage, limit)
 	}
 
-	_, err = os.Stat(cache.variants.keyToPath(string(keys[0])))
-	if err == nil {
+	if cache.variants.Exists(keys[0]) {
 		t.Errorf("least recently used variant %s must be evicted", keys[0])
 	}
 
@@ -350,8 +358,7 @@ func TestEvictToLimitEvictsLeastRecentlyUsedFirst(t *testing.T) {
 	}
 
 	for _, key := range keys[1:] {
-		_, err = os.Stat(cache.variants.keyToPath(string(key)))
-		if err != nil {
+		if !cache.variants.Exists(key) {
 			t.Errorf("more recently used variant %s must survive eviction", key)
 		}
 	}
@@ -379,8 +386,7 @@ func TestEvictionKeepsEverythingWhenUnderLimit(t *testing.T) {
 	}
 
 	for _, key := range keys {
-		_, err = os.Stat(cache.srcContent.keyToPath(string(key)))
-		if err != nil {
+		if !cache.srcContent.Exists(key) {
 			t.Errorf("source %s must not be evicted while usage is under the limit", key)
 		}
 
@@ -391,8 +397,7 @@ func TestEvictionKeepsEverythingWhenUnderLimit(t *testing.T) {
 		}
 	}
 
-	_, err = os.Stat(cache.variants.keyToPath(string(testVariantKeyOne)))
-	if err != nil {
+	if !cache.variants.Exists(testVariantKeyOne) {
 		t.Error("variant must not be evicted while usage is under the limit")
 	}
 
@@ -431,20 +436,27 @@ func assertDisabledCacheWritesAreNoOps(
 
 	ctx := t.Context()
 
-	err := cache.PutVariant(
-		ctx, imagerequest.CacheKey(req), bytes.NewReader([]byte("data")),
+	err := cache.StoreVariant(
+		ctx, imagerequest.CacheKey(req), bytes.NewReader([]byte("data")), "image/webp",
 	)
 	if err != nil {
-		t.Fatalf("PutVariant on disabled cache must be a no-op, got error: %v", err)
+		t.Fatalf("StoreVariant on disabled cache must be a no-op, got error: %v", err)
 	}
 
-	key, err := cache.PutSource(ctx, req.Source, bytes.NewReader([]byte("data")))
+	result := &httpfetcher.FetchResult{
+		StatusCode:    200,
+		ContentType:   testContentTypeJPEG,
+		ContentLength: 4,
+		Headers:       map[string][]string{},
+	}
+
+	key, err := cache.StoreSource(ctx, req, bytes.NewReader([]byte("data")), result)
 	if err != nil {
-		t.Fatalf("PutSource on disabled cache must be a no-op, got error: %v", err)
+		t.Fatalf("StoreSource on disabled cache must be a no-op, got error: %v", err)
 	}
 
 	if key != "" {
-		t.Errorf("PutSource on disabled cache returned key %q, want empty", key)
+		t.Errorf("StoreSource on disabled cache returned key %q, want empty", key)
 	}
 }
 
@@ -457,13 +469,14 @@ func assertDisabledCacheReadsAlwaysMiss(
 
 	ctx := t.Context()
 
-	reader, _, _, err := cache.Source(ctx, req.Source)
-	if !errors.Is(err, ErrNotFound) {
-		t.Fatalf("Source on disabled cache error = %v, want %v", err, ErrNotFound)
+	key, srcType, err := cache.LookupSource(ctx, req)
+	if err != nil {
+		t.Fatalf("LookupSource on disabled cache failed: %v", err)
 	}
 
-	if reader != nil {
-		t.Errorf("Source on disabled cache = reader %v, want none", reader)
+	if key != "" || srcType != "" {
+		t.Errorf("LookupSource on disabled cache = (%q, %q), want empty",
+			key, srcType)
 	}
 }
 
@@ -552,7 +565,7 @@ func TestEvictionRunsUnderWritePressure(t *testing.T) {
 }
 
 // TestEvictionRunsOnPeriodicSchedule writes three variant files straight
-// to disk, bypassing PutVariant, so they have no accounting rows and no
+// to disk, bypassing StoreVariant, so they have no accounting rows and no
 // write-pressure notification fires. Only a periodic reconciliation pass
 // can then adopt them, and only the eviction pass that follows it can
 // evict them.
@@ -594,7 +607,7 @@ func TestEvictionRunsOnPeriodicSchedule(t *testing.T) {
 	for i, key := range keys {
 		content := bytes.Repeat([]byte{fills[i]}, 1000)
 
-		err = cache.variants.Write(string(key), content)
+		_, err = cache.variants.Store(key, bytes.NewReader(content))
 		if err != nil {
 			t.Fatalf("failed to store variant file: %v", err)
 		}
@@ -613,8 +626,7 @@ func TestEvictionRunsOnPeriodicSchedule(t *testing.T) {
 		stored = 0
 
 		for _, key := range keys {
-			_, err = os.Stat(cache.variants.keyToPath(string(key)))
-			if err == nil {
+			if cache.variants.Exists(key) {
 				stored++
 			}
 		}
@@ -646,15 +658,18 @@ func TestStartEvictionReconcilesAccountingWithDisk(t *testing.T) {
 	// feature existed) must be adopted into the accounting.
 	untracked := bytes.Repeat([]byte{0x31}, 1000)
 
-	err := cache.variants.Write(string(testVariantKeyOne), untracked)
+	_, err := cache.variants.Store(
+		testVariantKeyOne, bytes.NewReader(untracked),
+	)
 	if err != nil {
 		t.Fatalf("failed to store untracked variant file: %v", err)
 	}
 
 	// An accounting row whose file is missing must be dropped.
 	_, err = cache.db.ExecContext(t.Context(),
-		`INSERT INTO variant_content (cache_key, size_bytes) VALUES (?, ?)`,
-		"deadbeef0001", 700,
+		`INSERT INTO variant_content (cache_key, size_bytes, content_type)
+		 VALUES (?, ?, ?)`,
+		"deadbeef0001", 700, "image/webp",
 	)
 	if err != nil {
 		t.Fatalf("failed to insert stale variant accounting row: %v", err)
@@ -701,295 +716,10 @@ func TestStartEvictionReconcilesAccountingWithDisk(t *testing.T) {
 	}
 }
 
-// logLineNaming returns the first line of logs, written by slog's JSON
-// handler, that is at level and names the variant key, or "" if none is.
-func logLineNaming(logs, level string, key imagerequest.VariantKey) string {
-	for line := range strings.Lines(logs) {
-		if strings.Contains(line, `"level":"`+level+`"`) &&
-			strings.Contains(line, `"cache_key":"`+string(key)+`"`) {
-			return line
-		}
-	}
-
-	return ""
-}
-
-// TestReconcileVariantRowsDropsOnlyRowsOfMissingFiles gives
-// reconcileVariantRows two tracked variants. The first one's file is a
-// symbolic link to itself, so its size cannot be read. Its row must stay,
-// with a warning naming its key and the error. The second one has no file.
-// Its row must go, with the info line for a missing file.
-func TestReconcileVariantRowsDropsOnlyRowsOfMissingFiles(t *testing.T) {
-	t.Parallel()
-
-	cache, _ := newEvictionTestCache(t, 1<<30)
-	storeEvictionTestVariant(t, cache, testVariantKeyOne, []byte("variant one"))
-	storeEvictionTestVariant(t, cache, testVariantKeyTwo, []byte("variant two"))
-
-	unreadablePath := cache.variants.keyToPath(string(testVariantKeyOne))
-
-	err := os.Remove(unreadablePath)
-	if err != nil {
-		t.Fatalf("failed to remove the first variant's file: %v", err)
-	}
-
-	err = os.Symlink(unreadablePath, unreadablePath)
-	if err != nil {
-		t.Fatalf("failed to link the first variant's path to itself: %v", err)
-	}
-
-	_, statErr := os.Stat(unreadablePath)
-	if statErr == nil || errors.Is(statErr, fs.ErrNotExist) {
-		t.Fatalf("os.Stat() of the first variant: error = %v, "+
-			"want an error other than a missing file", statErr)
-	}
-
-	err = os.Remove(cache.variants.keyToPath(string(testVariantKeyTwo)))
-	if err != nil {
-		t.Fatalf("failed to remove the second variant's file: %v", err)
-	}
-
-	var logBuf bytes.Buffer
-
-	cache.log = slog.New(slog.NewJSONHandler(&logBuf, nil))
-
-	err = cache.reconcileVariantRows(t.Context())
-	t.Logf("reconcileVariantRows() error = %v, log: %s", err, logBuf.String())
-
-	if err != nil {
-		t.Fatalf("reconcileVariantRows() error = %v", err)
-	}
-
-	rowQuery := `SELECT COUNT(*) FROM variant_content WHERE cache_key = ?`
-
-	if n := countRows(t, cache, rowQuery, string(testVariantKeyOne)); n != 1 {
-		t.Errorf("the variant whose size cannot be read has %d rows, want 1", n)
-	}
-
-	if n := countRows(t, cache, rowQuery, string(testVariantKeyTwo)); n != 0 {
-		t.Errorf("the variant with no file has %d rows, want 0", n)
-	}
-
-	logs := logBuf.String()
-
-	warning := logLineNaming(logs, "WARN", testVariantKeyOne)
-	if !strings.Contains(warning, statErr.Error()) {
-		t.Errorf("no warning names %s and the error %q", testVariantKeyOne, statErr)
-	}
-
-	if line := logLineNaming(logs, "INFO", testVariantKeyOne); line != "" {
-		t.Errorf("the variant whose size cannot be read was logged at info: %s", line)
-	}
-
-	dropped := logLineNaming(logs, "INFO", testVariantKeyTwo)
-	if !strings.Contains(dropped, "dropped accounting row for missing variant file") {
-		t.Errorf("no info line says the file of %s is missing", testVariantKeyTwo)
-	}
-}
-
-// openDirectoryNearPathLimit makes a chain of directories inside dir, each
-// named with 255 zeros, the longest name Linux allows. Linux refuses a path
-// of 4096 bytes or more, and the chain goes as deep as it can below that.
-// It returns the chain's deepest directory as an os.Root, closed when the
-// test ends. An entry made through it with a 255-byte name has a path even
-// the root user cannot read. The os.Root can make that entry because it
-// names the entry only by its name, not by the whole path.
-func openDirectoryNearPathLimit(t *testing.T, dir string) *os.Root {
-	t.Helper()
-
-	name := strings.Repeat("0", 255)
-	deepest := dir
-
-	for len(filepath.Join(deepest, name)) < 4096 {
-		deepest = filepath.Join(deepest, name)
-	}
-
-	err := os.MkdirAll(deepest, StorageDirPerm)
-	if err != nil {
-		t.Fatalf("failed to make a chain of directories: %v", err)
-	}
-
-	root, err := os.OpenRoot(deepest)
-	if err != nil {
-		t.Fatalf("os.OpenRoot(%s) error = %v", deepest, err)
-	}
-
-	t.Cleanup(func() { _ = root.Close() })
-
-	return root
-}
-
-// makeEntriesTooLongToRead makes a new directory and a new file in the
-// deepest directory of the chain that openDirectoryNearPathLimit makes
-// inside dir. Even the root user can then neither list the new directory
-// nor read the new file's info. It returns the paths of the new directory
-// and the new file.
-func makeEntriesTooLongToRead(t *testing.T, dir string) []string {
-	t.Helper()
-
-	deepest := openDirectoryNearPathLimit(t, dir)
-	dirName := strings.Repeat("0", 255)
-
-	err := deepest.Mkdir(dirName, StorageDirPerm)
-	if err != nil {
-		t.Fatalf("failed to make a directory too deep to list: %v", err)
-	}
-
-	fileName := strings.Repeat("1", 255)
-
-	err = deepest.WriteFile(fileName, []byte("unreadable"), StorageFilePerm)
-	if err != nil {
-		t.Fatalf("failed to make a file too deep to read: %v", err)
-	}
-
-	return []string{
-		filepath.Join(deepest.Name(), dirName),
-		filepath.Join(deepest.Name(), fileName),
-	}
-}
-
-// makeTempFileTooLongToRead makes a temp file in the deepest directory of
-// the chain that openDirectoryNearPathLimit makes inside dir. Even the
-// root user then cannot read the temp file's info. It returns the temp
-// file's path.
-func makeTempFileTooLongToRead(t *testing.T, dir string) string {
-	t.Helper()
-
-	deepest := openDirectoryNearPathLimit(t, dir)
-	name := tempFilePrefix + strings.Repeat("1", 255-len(tempFilePrefix))
-
-	err := deepest.WriteFile(name, []byte("partial"), StorageFilePerm)
-	if err != nil {
-		t.Fatalf("failed to make a temp file too deep to read: %v", err)
-	}
-
-	return filepath.Join(deepest.Name(), name)
-}
-
-// assertSkippedEntryWarning checks that logs hold the warning "skipped
-// unreadable entry in cache directory" naming path, with the error
-// ENAMETOOLONG for that path.
-func assertSkippedEntryWarning(t *testing.T, logs, path string) {
-	t.Helper()
-
-	for line := range strings.Lines(logs) {
-		if strings.Contains(line, `"level":"WARN"`) &&
-			strings.Contains(line, `"msg":"skipped unreadable entry in cache directory"`) &&
-			strings.Contains(line, `"path":"`+path+`"`) &&
-			strings.Contains(line, path+": "+syscall.ENAMETOOLONG.Error()) {
-			return
-		}
-	}
-
-	t.Errorf("no warning %q names %s with the error %q",
-		"skipped unreadable entry in cache directory", path, syscall.ENAMETOOLONG)
-}
-
-// TestReconciliationGoesOnPastEntriesItCannotRead puts, in each storage
-// directory, a directory the pass cannot list and a file whose info it
-// cannot read. The pass walks each directory in name order, so it reaches
-// them before the cache's files, whose keys start with a letter. It must
-// log a warning naming each one's path and the error, and still do the
-// rest of its work:
-//   - adopt a variant file that has no row
-//   - drop the row of a variant whose file is missing
-//   - remove a source file that has no row
-//   - correct a wrong total cache usage
-func TestReconciliationGoesOnPastEntriesItCannotRead(t *testing.T) {
-	t.Parallel()
-
-	cache, _ := newEvictionTestCache(t, 1<<30)
-	ctx := t.Context()
-
-	untrackedVariant := []byte("variant with no row")
-
-	err := cache.variants.Write(string(testVariantKeyOne), untrackedVariant)
-	if err != nil {
-		t.Fatalf("failed to write a variant file with no row: %v", err)
-	}
-
-	storeEvictionTestVariant(t, cache, testVariantKeyTwo, []byte("variant two"))
-
-	err = os.Remove(cache.variants.keyToPath(string(testVariantKeyTwo)))
-	if err != nil {
-		t.Fatalf("failed to remove the second variant's file: %v", err)
-	}
-
-	untrackedSourceKey := "ffeeddcc0001"
-
-	err = cache.srcContent.Write(untrackedSourceKey, []byte("source with no row"))
-	if err != nil {
-		t.Fatalf("failed to write a source file with no row: %v", err)
-	}
-
-	_, err = cache.db.ExecContext(ctx,
-		`UPDATE cache_usage SET total_size_bytes = 1 WHERE id = 1`)
-	if err != nil {
-		t.Fatalf("failed to set a wrong total: %v", err)
-	}
-
-	unreadable := slices.Concat(
-		makeEntriesTooLongToRead(t, cache.variants.baseDir),
-		makeEntriesTooLongToRead(t, cache.srcContent.baseDir),
-	)
-
-	logs := reconcileAsAtStartup(t, cache)
-
-	for _, path := range unreadable {
-		assertSkippedEntryWarning(t, logs, path)
-	}
-
-	rowQuery := `SELECT COUNT(*) FROM variant_content WHERE cache_key = ?`
-
-	if n := countRows(t, cache, rowQuery, string(testVariantKeyOne)); n != 1 {
-		t.Errorf("the variant file with no row got %d rows, want 1", n)
-	}
-
-	if n := countRows(t, cache, rowQuery, string(testVariantKeyTwo)); n != 0 {
-		t.Errorf("the variant with no file kept %d rows, want 0", n)
-	}
-
-	_, err = os.Stat(cache.srcContent.keyToPath(untrackedSourceKey))
-	if err == nil {
-		t.Error("the source file with no row is still on disk")
-	}
-
-	usage, err := cache.UsageBytes(ctx)
-	if err != nil {
-		t.Fatalf("UsageBytes() error = %v", err)
-	}
-
-	if usage != int64(len(untrackedVariant)) {
-		t.Errorf("UsageBytes() = %d, want %d, the size of the adopted variant",
-			usage, len(untrackedVariant))
-	}
-}
-
-// TestReconciliationWarnsOfTempFilesWhoseInfoItCannotRead puts, in each
-// storage directory, a temp file whose info the pass cannot read. The
-// pass must log a warning naming each one's path and the error, as it
-// does for any other file whose info it cannot read.
-func TestReconciliationWarnsOfTempFilesWhoseInfoItCannotRead(t *testing.T) {
-	t.Parallel()
-
-	cache, _ := newEvictionTestCache(t, 1<<30)
-
-	unreadable := []string{
-		makeTempFileTooLongToRead(t, cache.variants.baseDir),
-		makeTempFileTooLongToRead(t, cache.srcContent.baseDir),
-	}
-
-	logs := reconcileAsAtStartup(t, cache)
-
-	for _, path := range unreadable {
-		assertSkippedEntryWarning(t, logs, path)
-	}
-}
-
 // TestPeriodicReconciliationAdoptsFileThatAppearsAfterStartup proves
 // reconciliation is not a one-shot startup-only pass: it must also run
 // on the periodic ticker, so a variant file that lands on disk with no
-// accounting row well after startup (e.g. because PutVariant's
+// accounting row well after startup (e.g. because StoreVariant's
 // best-effort accounting insert failed under transient contention, or
 // any other cause of an untracked file appearing during steady-state
 // operation) is still adopted into accounting eventually, rather than
@@ -1025,12 +755,14 @@ func TestPeriodicReconciliationAdoptsFileThatAppearsAfterStartup(t *testing.T) {
 
 	// Simulate a variant whose accounting insert failed after the
 	// process was already running and serving requests: the content
-	// file is written directly, bypassing PutVariant's (and thus its
+	// file is written directly, bypassing StoreVariant's (and thus its
 	// accounting insert) entirely, exactly as would happen if that
 	// insert had failed and only the file write had succeeded.
 	untracked := bytes.Repeat([]byte{0x41}, 900)
 
-	err = cache.variants.Write("aabbccdd0099", untracked)
+	_, err = cache.variants.Store(
+		"aabbccdd0099", bytes.NewReader(untracked),
+	)
 	if err != nil {
 		t.Fatalf("failed to store untracked variant file: %v", err)
 	}
@@ -1336,15 +1068,13 @@ func assertOnlyOldestSourceEvicted(
 ) {
 	t.Helper()
 
-	_, err := os.Stat(cache.srcContent.keyToPath(string(keys[0])))
-	if err == nil {
+	if cache.srcContent.Exists(keys[0]) {
 		t.Errorf("source %s, evicted when the context was cancelled, "+
 			"is still on disk", keys[0])
 	}
 
 	for _, key := range keys[1:] {
-		_, err = os.Stat(cache.srcContent.keyToPath(string(key)))
-		if err != nil {
+		if !cache.srcContent.Exists(key) {
 			t.Errorf("source %s was evicted after the context was cancelled", key)
 		}
 

internal/imgcache/filestore.go

@@ -1,185 +0,0 @@
-package imgcache
-
-import (
-	"errors"
-	"fmt"
-	"os"
-	"path/filepath"
-)
-
-// Storage constants.
-const (
-	// StorageDirPerm is the permission mode for storage directories.
-	StorageDirPerm = 0750
-	// StorageFilePerm is the permission mode for storage files.
-	StorageFilePerm = 0600
-	// MinHashLength is the minimum hash length for path splitting.
-	MinHashLength = 4
-)
-
-// Storage errors.
-var (
-	ErrNotFound = errors.New("content not found")
-)
-
-// FileStore is a directory of files, each named by a hex key. The file for
-// a key is at <basedir>/<ab>/<cd>/<key>, where <ab> and <cd> are the key's
-// first and second pairs of characters. The cache keeps its source images in
-// one FileStore and its variants in another.
-type FileStore struct {
-	baseDir string
-}
-
-// NewFileStore creates the directory baseDir if it is missing and returns
-// the FileStore of the files in it.
-func NewFileStore(baseDir string) (*FileStore, error) {
-	err := os.MkdirAll(baseDir, StorageDirPerm)
-	if err != nil {
-		return nil, fmt.Errorf("failed to create storage directory: %w", err)
-	}
-
-	return &FileStore{baseDir: baseDir}, nil
-}
-
-// Write writes data with writeFileSynced to the file for key, replacing any
-// file already there.
-func (s *FileStore) Write(key string, data []byte) error {
-	path := s.keyToPath(key)
-
-	err := os.MkdirAll(filepath.Dir(path), StorageDirPerm)
-	if err != nil {
-		return fmt.Errorf("failed to create directory: %w", err)
-	}
-
-	return writeFileSynced(path, data)
-}
-
-// Open opens the file for key and returns it with its size in bytes. A
-// missing file is ErrNotFound.
-func (s *FileStore) Open(key string) (*os.File, int64, error) {
-	f, err := os.Open(s.keyToPath(key))
-	if err != nil {
-		if os.IsNotExist(err) {
-			return nil, 0, ErrNotFound
-		}
-
-		return nil, 0, fmt.Errorf("failed to open content: %w", err)
-	}
-
-	stat, err := f.Stat()
-	if err != nil {
-		_ = f.Close()
-
-		return nil, 0, fmt.Errorf("failed to stat content: %w", err)
-	}
-
-	return f, stat.Size(), nil
-}
-
-// Size returns the size in bytes of the file for key. A missing file is
-// ErrNotFound.
-func (s *FileStore) Size(key string) (int64, error) {
-	stat, err := os.Stat(s.keyToPath(key))
-	if err != nil {
-		if os.IsNotExist(err) {
-			return 0, ErrNotFound
-		}
-
-		return 0, fmt.Errorf("failed to stat content: %w", err)
-	}
-
-	return stat.Size(), nil
-}
-
-// Delete removes the file for key. A missing file is not an error.
-func (s *FileStore) Delete(key string) error {
-	err := os.Remove(s.keyToPath(key))
-	if err != nil && !os.IsNotExist(err) {
-		return fmt.Errorf("failed to delete content: %w", err)
-	}
-
-	return nil
-}
-
-// writeFileSynced writes data to path through a temp file in the same
-// directory: the temp file is synced to disk, renamed to path, and the
-// directory synced after, so that neither a concurrent reader nor a
-// crash finds a partial file under path. When the directory sync fails,
-// the file is removed from path, so that a failed write leaves no file
-// there.
-func writeFileSynced(path string, data []byte) error {
-	dir := filepath.Dir(path)
-
-	tmpFile, err := os.CreateTemp(dir, ".tmp-*")
-	if err != nil {
-		return fmt.Errorf("failed to create temp file: %w", err)
-	}
-
-	tmpPath := tmpFile.Name()
-
-	_, err = tmpFile.Write(data)
-	if err != nil {
-		_ = tmpFile.Close()
-		_ = os.Remove(tmpPath)
-
-		return fmt.Errorf("failed to write temp file: %w", err)
-	}
-
-	err = tmpFile.Sync()
-	if err != nil {
-		_ = tmpFile.Close()
-		_ = os.Remove(tmpPath)
-
-		return fmt.Errorf("failed to sync temp file: %w", err)
-	}
-
-	err = tmpFile.Close()
-	if err != nil {
-		_ = os.Remove(tmpPath)
-
-		return fmt.Errorf("failed to close temp file: %w", err)
-	}
-
-	err = os.Rename(filepath.Clean(tmpPath), filepath.Clean(path))
-	if err != nil {
-		_ = os.Remove(tmpPath)
-
-		return fmt.Errorf("failed to rename temp file: %w", err)
-	}
-
-	err = syncDirectory(dir)
-	if err != nil {
-		_ = os.Remove(path)
-
-		return err
-	}
-
-	return nil
-}
-
-// syncDirectory syncs the directory dir to disk, so that a file just
-// renamed into it is still there after a crash.
-func syncDirectory(dir string) error {
-	d, err := os.Open(filepath.Clean(dir))
-	if err != nil {
-		return fmt.Errorf("failed to open directory: %w", err)
-	}
-
-	err = d.Sync()
-	_ = d.Close()
-
-	if err != nil {
-		return fmt.Errorf("failed to sync directory: %w", err)
-	}
-
-	return nil
-}
-
-// keyToPath converts a key to a file path: <basedir>/<ab>/<cd>/<key>
-func (s *FileStore) keyToPath(key string) string {
-	if len(key) < MinHashLength {
-		return filepath.Join(s.baseDir, key)
-	}
-
-	return filepath.Join(s.baseDir, key[0:2], key[2:4], key)
-}

internal/imgcache/filestore_internal_test.go

@@ -1,184 +0,0 @@
-package imgcache
-
-import (
-	"bytes"
-	"errors"
-	"io"
-	"os"
-	"path/filepath"
-	"testing"
-
-	"sneak.berlin/go/pixa/internal/imagerequest"
-)
-
-func TestFileStore_WriteAndOpen(t *testing.T) {
-	t.Parallel()
-
-	tmpDir := t.TempDir()
-
-	storage, err := NewFileStore(tmpDir)
-	if err != nil {
-		t.Fatalf("NewFileStore() error = %v", err)
-	}
-
-	content := []byte("hello world")
-	key := string(imagerequest.Source{Host: testHostCDN, Path: testPathCat}.Key())
-
-	err = storage.Write(key, content)
-	if err != nil {
-		t.Fatalf("Write() error = %v", err)
-	}
-
-	// Verify file exists at expected path
-	expectedPath := filepath.Join(tmpDir, key[0:2], key[2:4], key)
-
-	_, err = os.Stat(expectedPath)
-	if err != nil {
-		t.Errorf("File not at expected path %s: %v", expectedPath, err)
-	}
-
-	// Open and verify size and content
-	r, size, err := storage.Open(key)
-	if err != nil {
-		t.Fatalf("Open() error = %v", err)
-	}
-
-	defer func() { _ = r.Close() }()
-
-	if size != int64(len(content)) {
-		t.Errorf("Open() size = %d, want %d", size, len(content))
-	}
-
-	loaded, err := io.ReadAll(r)
-	if err != nil {
-		t.Fatalf("ReadAll() error = %v", err)
-	}
-
-	if !bytes.Equal(loaded, content) {
-		t.Errorf("Open() content = %q, want %q", loaded, content)
-	}
-}
-
-func TestFileStore_OpenNotFound(t *testing.T) {
-	t.Parallel()
-
-	tmpDir := t.TempDir()
-
-	storage, err := NewFileStore(tmpDir)
-	if err != nil {
-		t.Fatalf("NewFileStore() error = %v", err)
-	}
-
-	_, _, err = storage.Open("nonexistent")
-	if !errors.Is(err, ErrNotFound) {
-		t.Errorf("Open() error = %v, want ErrNotFound", err)
-	}
-}
-
-// TestFileStore_Size checks that Size returns the size of a written file,
-// and ErrNotFound for a key with no file.
-func TestFileStore_Size(t *testing.T) {
-	t.Parallel()
-
-	storage, err := NewFileStore(t.TempDir())
-	if err != nil {
-		t.Fatalf("NewFileStore() error = %v", err)
-	}
-
-	content := []byte("the file's content")
-	key := string(imagerequest.Source{Host: testHostCDN, Path: testPathCat}.Key())
-
-	err = storage.Write(key, content)
-	if err != nil {
-		t.Fatalf("Write() error = %v", err)
-	}
-
-	size, err := storage.Size(key)
-	if err != nil || size != int64(len(content)) {
-		t.Errorf("Size() = %d, error %v; want %d", size, err, len(content))
-	}
-
-	_, err = storage.Size("nonexistent")
-	if !errors.Is(err, ErrNotFound) {
-		t.Errorf("Size() of a missing file error = %v, want ErrNotFound", err)
-	}
-}
-
-func TestFileStore_Delete(t *testing.T) {
-	t.Parallel()
-
-	tmpDir := t.TempDir()
-
-	storage, err := NewFileStore(tmpDir)
-	if err != nil {
-		t.Fatalf("NewFileStore() error = %v", err)
-	}
-
-	content := []byte("to be deleted")
-	key := string(imagerequest.Source{Host: testHostCDN, Path: testPathCat}.Key())
-	path := storage.keyToPath(key)
-
-	err = storage.Write(key, content)
-	if err != nil {
-		t.Fatalf("Write() error = %v", err)
-	}
-
-	_, err = os.Stat(path)
-	if err != nil {
-		t.Errorf("file missing before Delete(): %v", err)
-	}
-
-	err = storage.Delete(key)
-	if err != nil {
-		t.Fatalf("Delete() error = %v", err)
-	}
-
-	_, err = os.Stat(path)
-	if err == nil {
-		t.Error("file still on disk after Delete()")
-	}
-}
-
-func TestFileStore_DeleteNonexistent(t *testing.T) {
-	t.Parallel()
-
-	tmpDir := t.TempDir()
-
-	storage, err := NewFileStore(tmpDir)
-	if err != nil {
-		t.Fatalf("NewFileStore() error = %v", err)
-	}
-
-	// Should not error
-	err = storage.Delete("nonexistent")
-	if err != nil {
-		t.Errorf("Delete() error = %v, want nil", err)
-	}
-}
-
-func TestFileStore_KeyToPath(t *testing.T) {
-	t.Parallel()
-
-	tmpDir := t.TempDir()
-
-	storage, err := NewFileStore(tmpDir)
-	if err != nil {
-		t.Fatalf("NewFileStore() error = %v", err)
-	}
-
-	// Test by writing and verifying the resulting path structure
-	content := []byte("test content for path verification")
-	key := string(imagerequest.Source{Host: testHostCDN, Path: testPathCat}.Key())
-
-	err = storage.Write(key, content)
-	if err != nil {
-		t.Fatalf("Write() error = %v", err)
-	}
-
-	expectedPath := filepath.Join(tmpDir, key[0:2], key[2:4], key)
-
-	_, err = os.Stat(expectedPath)
-	if err != nil {
-		t.Errorf("File not at expected path %s: %v", expectedPath, err)
-	}
-}

internal/imgcache/imgcache.go

@@ -0,0 +1,66 @@
+// Package imgcache provides interfaces and types for the image caching proxy.
+package imgcache
+
+import (
+	"context"
+	"io"
+	"time"
+
+	"sneak.berlin/go/pixa/internal/imagerequest"
+)
+
+// ImageResponse represents a processed image ready to serve
+type ImageResponse struct {
+	// Content is the image data reader
+	Content io.ReadCloser
+	// ContentLength is the size in bytes (-1 if unknown)
+	ContentLength int64
+	// ContentType is the MIME type of the response
+	ContentType string
+	// ETag is the entity tag for caching
+	ETag string
+	// LastModified is when the content was last modified
+	LastModified time.Time
+	// CacheStatus indicates HIT, MISS, or STALE
+	CacheStatus CacheStatus
+	// FetchedBytes is the number of bytes fetched from upstream (0 if cache hit)
+	FetchedBytes int64
+}
+
+// CacheStatus indicates whether the response was served from cache.
+type CacheStatus string
+
+// Cache status values for response headers.
+const (
+	CacheHit   CacheStatus = "HIT"
+	CacheMiss  CacheStatus = "MISS"
+	CacheStale CacheStatus = "STALE"
+)
+
+// ImageCache is the main interface for the image caching proxy
+type ImageCache interface {
+	// Get retrieves a processed image, fetching and processing if necessary
+	Get(ctx context.Context, req *imagerequest.Request) (*ImageResponse, error)
+
+	// Warm pre-fetches and caches an image without returning it
+	Warm(ctx context.Context, req *imagerequest.Request) error
+
+	// Stats returns cache statistics
+	Stats(ctx context.Context) (*CacheStats, error)
+}
+
+// CacheStats contains cache statistics
+type CacheStats struct {
+	// TotalItems is the number of cached source images plus processed
+	// variants
+	TotalItems int64
+	// TotalSizeBytes is the total size of cached source images and
+	// processed variants
+	TotalSizeBytes int64
+	// HitCount is the number of cache hits
+	HitCount int64
+	// MissCount is the number of cache misses
+	MissCount int64
+	// HitRate is HitCount / (HitCount + MissCount)
+	HitRate float64
+}

internal/imgcache/max_concurrent_processing_internal_test.go

@@ -1,4 +1,4 @@
-package imageproxy
+package imgcache
 
 import (
 	"image/color"
@@ -41,8 +41,7 @@ func holdProcessingSlot(
 	input, feed := io.Pipe()
 
 	go func() {
-		_, _ = proc.Process(t.Context(), input, imagerequest.FormatJPEG,
-			&imagerequest.Transform{})
+		_, _ = proc.Process(t.Context(), input, &imagerequest.Transform{})
 	}()
 
 	_, err := feed.Write([]byte{0})
@@ -56,19 +55,18 @@ func holdProcessingSlot(
 	return release
 }
 
-// TestProxy_Get_WaitsForSlotBeforeReadingCachedSource checks that a
+// TestService_Get_WaitsForSlotBeforeReadingCachedSource checks that a
 // request whose source is cached holds none of it while it waits for a
-// processing slot: past the first bytes, which give the source's format, it
-// reads the cached file only once it has a slot. With the only slot held, a
-// request for a new width of the cached 100x100 photo waits; the cached file
-// is then rewritten as a 100x50 image before the slot is freed, so the
-// request must answer with that image scaled to 40x20.
-func TestProxy_Get_WaitsForSlotBeforeReadingCachedSource(t *testing.T) {
+// processing slot: it reads the cached file only once it has a slot. With
+// the only slot held, a request for a new width of the cached 100x100 photo
+// waits; the cached file is then rewritten as a 100x50 image before the slot
+// is freed, so the request must answer with that image scaled to 40x20.
+func TestService_Get_WaitsForSlotBeforeReadingCachedSource(t *testing.T) {
 	t.Parallel()
 
-	svc, fixtures := setupTestProxy(t)
+	svc, fixtures := SetupTestService(t)
 	svc.processor = imageprocessor.New(
-		imageprocessor.Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1},
+		imageprocessor.Params{MaxConcurrentProcessing: 1},
 	)
 
 	// A first request caches the photo as a source.
@@ -79,15 +77,13 @@ func TestProxy_Get_WaitsForSlotBeforeReadingCachedSource(t *testing.T) {
 
 	_ = resp.Content.Close()
 
-	cachedSource := widthOnlyRequest(fixtures, 50).Source
-
-	reader, _, _, err := svc.cache.Source(t.Context(), cachedSource)
-	if err != nil {
-		t.Fatalf("Source() error = %v; want the cached source", err)
+	sourceKey, _, err := svc.cache.LookupSource(t.Context(),
+		widthOnlyRequest(fixtures, 50))
+	if err != nil || sourceKey == "" {
+		t.Fatalf("LookupSource() = %q, %v; want the cached source",
+			sourceKey, err)
 	}
 
-	_ = reader.Close()
-
 	release := holdProcessingSlot(t, svc.processor)
 
 	var (
@@ -107,7 +103,7 @@ func TestProxy_Get_WaitsForSlotBeforeReadingCachedSource(t *testing.T) {
 	// before waiting, it would have read it by now.
 	time.Sleep(100 * time.Millisecond)
 
-	err = os.WriteFile(sourceFilePath(svc, cachedSource.Key()),
+	err = os.WriteFile(svc.cache.srcContent.keyToPath(sourceKey),
 		generateTestJPEG(t, 100, 50, color.RGBA{0, 0, 255, 255}), 0o600)
 	if err != nil {
 		t.Fatalf("failed to rewrite the cached source: %v", err)

internal/imgcache/module.go

@@ -0,0 +1,8 @@
+package imgcache
+
+import "time"
+
+// CacheConfig defaults.
+const (
+	DefaultNegativeTTL = 5 * time.Minute
+)

internal/imgcache/negative_cache_internal_test.go

@@ -7,7 +7,6 @@ import (
 	"testing"
 	"time"
 
-	"github.com/prometheus/client_golang/prometheus"
 	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
@@ -17,11 +16,10 @@ func TestNegativeCache_StoreAndCheck(t *testing.T) {
 	db := setupTestDB(t)
 	dir := t.TempDir()
 
-	cache, err := NewCache(db, Config{
+	cache, err := NewCache(db, CacheConfig{
 		StateDir:    dir,
 		NegativeTTL: 5 * time.Minute,
-		MaxBytes:    1 << 30,
-	}, prometheus.NewRegistry())
+	})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -35,7 +33,7 @@ func TestNegativeCache_StoreAndCheck(t *testing.T) {
 	}
 
 	// Initially should not be in negative cache
-	hit, err := cache.Failure(ctx, req.Source)
+	hit, err := cache.checkNegativeCache(ctx, req)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -45,13 +43,13 @@ func TestNegativeCache_StoreAndCheck(t *testing.T) {
 	}
 
 	// Store a negative entry
-	err = cache.PutFailure(ctx, req.Source)
+	err = cache.StoreNegative(ctx, req, 404, "not found")
 	if err != nil {
 		t.Fatal(err)
 	}
 
 	// Now should be in negative cache
-	hit, err = cache.Failure(ctx, req.Source)
+	hit, err = cache.checkNegativeCache(ctx, req)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -67,11 +65,10 @@ func TestNegativeCache_Expired(t *testing.T) {
 	db := setupTestDB(t)
 	dir := t.TempDir()
 
-	cache, err := NewCache(db, Config{
+	cache, err := NewCache(db, CacheConfig{
 		StateDir:    dir,
 		NegativeTTL: 1 * time.Millisecond, // very short TTL
-		MaxBytes:    1 << 30,
-	}, prometheus.NewRegistry())
+	})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -85,7 +82,7 @@ func TestNegativeCache_Expired(t *testing.T) {
 	}
 
 	// Store a negative entry with very short TTL
-	err = cache.PutFailure(ctx, req.Source)
+	err = cache.StoreNegative(ctx, req, 500, "server error")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -94,7 +91,7 @@ func TestNegativeCache_Expired(t *testing.T) {
 	time.Sleep(10 * time.Millisecond)
 
 	// Should no longer be in negative cache
-	hit, err := cache.Failure(ctx, req.Source)
+	hit, err := cache.checkNegativeCache(ctx, req)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -104,6 +101,72 @@ func TestNegativeCache_Expired(t *testing.T) {
 	}
 }
 
+// TestService_Get_ServesCachedVariantOfNegativeCachedURL caches a variant of
+// the test photo, then keeps a failed fetch of the photo's URL in the negative
+// cache, as a failed fetch for another variant does once the source has been
+// evicted. The cached variant is still served, and a variant not in the cache
+// is made from the cached source. Once the source is evicted, a variant not in
+// the cache needs a fetch and is refused.
+func TestService_Get_ServesCachedVariantOfNegativeCachedURL(t *testing.T) {
+	t.Parallel()
+
+	svc, fixtures := SetupTestService(t)
+
+	resp, err := svc.Get(t.Context(), photoVariant(fixtures, 85, imagerequest.FitCover))
+	if err != nil {
+		t.Fatalf("Get() first request error = %v", err)
+	}
+
+	_ = resp.Content.Close()
+
+	err = svc.cache.StoreNegative(t.Context(),
+		photoVariant(fixtures, 85, imagerequest.FitCover),
+		httpStatusBadGateway, "upstream answered 503")
+	if err != nil {
+		t.Fatalf("StoreNegative() error = %v", err)
+	}
+
+	resp, err = svc.Get(t.Context(), photoVariant(fixtures, 85, imagerequest.FitCover))
+	if err != nil {
+		t.Fatalf("Get() of the cached variant error = %v", err)
+	}
+
+	_ = resp.Content.Close()
+
+	if resp.CacheStatus != CacheHit {
+		t.Errorf("cached variant CacheStatus = %q, want %q",
+			resp.CacheStatus, CacheHit)
+	}
+
+	resp, err = svc.Get(t.Context(), photoVariant(fixtures, 40, imagerequest.FitCover))
+	t.Logf("Get() of a variant made from the cached source: error = %v", err)
+
+	if err != nil {
+		t.Fatalf("Get() of a variant made from the cached source error = %v", err)
+	}
+
+	_ = resp.Content.Close()
+
+	sourceKey, _, err := svc.cache.LookupSource(t.Context(),
+		photoVariant(fixtures, 85, imagerequest.FitCover))
+	if err != nil || sourceKey == "" {
+		t.Fatalf("LookupSource() = %q, %v, want the cached source", sourceKey, err)
+	}
+
+	err = svc.cache.evictSourceBlob(t.Context(), sourceKey)
+	if err != nil {
+		t.Fatalf("evictSourceBlob() error = %v", err)
+	}
+
+	_, err = svc.Get(t.Context(), photoVariant(fixtures, 60, imagerequest.FitCover))
+	t.Logf("Get() of a variant whose source was evicted: error = %v", err)
+
+	if !errors.Is(err, ErrNegativeCached) {
+		t.Errorf("Get() of a variant whose source was evicted error = %v, want %v",
+			err, ErrNegativeCached)
+	}
+}
+
 // TestEvictionLoopRemovesExpiredNegativeCacheRows stores a failed fetch
 // that expires a second later and starts the eviction loop with a short
 // interval: a later tick must remove its row although its URL is never
@@ -114,22 +177,22 @@ func TestEvictionLoopRemovesExpiredNegativeCacheRows(t *testing.T) {
 	t.Parallel()
 
 	tests := []struct {
-		name     string
-		maxBytes int64
+		name             string
+		disableDiskCache bool
 	}{
-		{name: "disk cache enabled", maxBytes: 1 << 30},
-		{name: "disk cache disabled", maxBytes: 0},
+		{name: "disk cache enabled", disableDiskCache: false},
+		{name: "disk cache disabled", disableDiskCache: true},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			cache, err := NewCache(evictionTestDB(t), Config{
-				StateDir:    t.TempDir(),
-				NegativeTTL: time.Second,
-				MaxBytes:    tt.maxBytes,
-			}, prometheus.NewRegistry())
+			cache, err := NewCache(evictionTestDB(t), CacheConfig{
+				StateDir:         t.TempDir(),
+				NegativeTTL:      time.Second,
+				DisableDiskCache: tt.disableDiskCache,
+			})
 			if err != nil {
 				t.Fatalf("failed to create cache: %v", err)
 			}
@@ -138,17 +201,17 @@ func TestEvictionLoopRemovesExpiredNegativeCacheRows(t *testing.T) {
 				Source: imagerequest.Source{Host: testHostExample, Path: "/gone.jpg"},
 			}
 
-			err = cache.PutFailure(t.Context(), expired.Source)
+			err = cache.StoreNegative(t.Context(), expired, 404, "not found")
 			if err != nil {
-				t.Fatalf("PutFailure failed: %v", err)
+				t.Fatalf("StoreNegative failed: %v", err)
 			}
 
 			const notExpiredPath = "/later.jpg"
 
 			_, err = cache.db.ExecContext(t.Context(), `
 				INSERT INTO negative_cache
-					(source_host, source_path, expires_at)
-				VALUES (?, ?, datetime('now', '+1 hour'))
+					(source_host, source_path, status_code, expires_at)
+				VALUES (?, ?, 404, datetime('now', '+1 hour'))
 			`, testHostExample, notExpiredPath)
 			if err != nil {
 				t.Fatalf("failed to insert a row that has not expired: %v", err)
@@ -203,9 +266,7 @@ func negativeCacheRowCount(tb testing.TB, cache *Cache, sourcePath string) int {
 func TestCleanExpiredDeletesInBatches(t *testing.T) {
 	t.Parallel()
 
-	cache, err := NewCache(evictionTestDB(t),
-		Config{StateDir: t.TempDir(), MaxBytes: 1 << 30},
-		prometheus.NewRegistry())
+	cache, err := NewCache(evictionTestDB(t), CacheConfig{StateDir: t.TempDir()})
 	if err != nil {
 		t.Fatalf("failed to create cache: %v", err)
 	}
@@ -218,8 +279,8 @@ func TestCleanExpiredDeletesInBatches(t *testing.T) {
 
 	_, err = cache.db.ExecContext(ctx, `
 		INSERT INTO negative_cache
-			(source_host, source_path, expires_at)
-		VALUES (?, ?, datetime('now', '+1 hour'))
+			(source_host, source_path, status_code, expires_at)
+		VALUES (?, ?, 404, datetime('now', '+1 hour'))
 	`, testHostExample, notExpiredPath)
 	if err != nil {
 		t.Fatalf("failed to insert a row that has not expired: %v", err)
@@ -259,9 +320,7 @@ func TestCleanExpiredDeletesInBatches(t *testing.T) {
 func TestCleanExpiredRemovesMoreThanOneBatch(t *testing.T) {
 	t.Parallel()
 
-	cache, err := NewCache(evictionTestDB(t),
-		Config{StateDir: t.TempDir(), MaxBytes: 1 << 30},
-		prometheus.NewRegistry())
+	cache, err := NewCache(evictionTestDB(t), CacheConfig{StateDir: t.TempDir()})
 	if err != nil {
 		t.Fatalf("failed to create cache: %v", err)
 	}
@@ -291,9 +350,7 @@ func TestCleanExpiredRemovesMoreThanOneBatch(t *testing.T) {
 func TestCleanExpiredStopsOnceContextEnds(t *testing.T) {
 	t.Parallel()
 
-	cache, err := NewCache(evictionTestDB(t),
-		Config{StateDir: t.TempDir(), MaxBytes: 1 << 30},
-		prometheus.NewRegistry())
+	cache, err := NewCache(evictionTestDB(t), CacheConfig{StateDir: t.TempDir()})
 	if err != nil {
 		t.Fatalf("failed to create cache: %v", err)
 	}
@@ -321,8 +378,8 @@ func insertExpiredNegativeCacheRows(t *testing.T, cache *Cache, count int) {
 	for i := range count {
 		_, err := cache.db.ExecContext(t.Context(), `
 			INSERT INTO negative_cache
-				(source_host, source_path, expires_at)
-			VALUES (?, ?, datetime('now', '-1 hour'))
+				(source_host, source_path, status_code, expires_at)
+			VALUES (?, ?, 404, datetime('now', '-1 hour'))
 		`, testHostExample, "/expired/"+strconv.Itoa(i)+".jpg")
 		if err != nil {
 			t.Fatalf("failed to insert an expired row: %v", err)
@@ -345,3 +402,15 @@ func negativeCacheTableRowCount(tb testing.TB, cache *Cache) int {
 
 	return count
 }
+
+func TestService_Get_ReturnsErrorForNegativeCachedURL(t *testing.T) {
+	t.Parallel()
+
+	// This test verifies that Service.Get() checks the negative cache
+	// We can't easily test the full pipeline without vips, but we can
+	// verify the error type
+	err := ErrNegativeCached
+	if !errors.Is(err, ErrNegativeCached) {
+		t.Error("ErrNegativeCached should be identifiable with errors.Is")
+	}
+}

internal/imgcache/partial_cache_files_internal_test.go

@@ -12,6 +12,67 @@ import (
 	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
+// getImage calls Get for req and returns the image it answered with and
+// its cache status.
+func getImage(
+	t *testing.T, svc *Service, req *imagerequest.Request,
+) ([]byte, CacheStatus) {
+	t.Helper()
+
+	resp, err := svc.Get(t.Context(), req)
+	if err != nil {
+		t.Fatalf("Get() of quality %d error = %v", req.Transform.Quality, err)
+	}
+
+	defer func() { _ = resp.Content.Close() }()
+
+	body, err := io.ReadAll(resp.Content)
+	if err != nil {
+		t.Fatalf("reading the image of quality %d: %v", req.Transform.Quality, err)
+	}
+
+	return body, resp.CacheStatus
+}
+
+// fileSize returns the size of the file at path.
+func fileSize(t *testing.T, path string) int64 {
+	t.Helper()
+
+	info, err := os.Stat(path)
+	if err != nil {
+		t.Fatalf("stat %s: %v", path, err)
+	}
+
+	return info.Size()
+}
+
+// truncateFile cuts the file at path down to size bytes.
+func truncateFile(t *testing.T, path string, size int64) {
+	t.Helper()
+
+	t.Logf("cutting %s from %d to %d bytes",
+		filepath.Base(path), fileSize(t, path), size)
+
+	err := os.Truncate(path, size)
+	if err != nil {
+		t.Fatalf("truncating %s: %v", path, err)
+	}
+}
+
+// cachedSourcePath returns the path of the cached source file req uses.
+func cachedSourcePath(
+	t *testing.T, svc *Service, req *imagerequest.Request,
+) string {
+	t.Helper()
+
+	sourceKey, _, err := svc.cache.LookupSource(t.Context(), req)
+	if err != nil || sourceKey == "" {
+		t.Fatalf("LookupSource() = %q, %v; want the cached source", sourceKey, err)
+	}
+
+	return svc.cache.srcContent.keyToPath(sourceKey)
+}
+
 // reconcileAsAtStartup runs the cache's reconciliation pass, as pixa does
 // when it starts, and returns what the pass logged.
 func reconcileAsAtStartup(t *testing.T, cache *Cache) string {
@@ -46,67 +107,131 @@ func assertWarningNames(t *testing.T, logs, path string) {
 	t.Errorf("reconciliation logged no warning naming %s", path)
 }
 
-// TestReconciliationRemovesDamagedFiles empties a cached source file and a
-// cached variant file, or cuts them to half their size, as a crash or a
-// restored snapshot could. It checks that the reconciliation pass removes
-// each file and its row, with a warning naming the file.
-func TestReconciliationRemovesDamagedFiles(t *testing.T) {
+// TestService_Get_FetchesAgainForEmptyCachedSource empties the cached source
+// file, as a crash or a restored snapshot could, and runs the reconciliation
+// pass, which must remove it with a warning naming it. It then asks for two
+// new sizes of the source: the first must fetch it again and cache it whole,
+// so that the second is made from the cache without a third fetch.
+func TestService_Get_FetchesAgainForEmptyCachedSource(t *testing.T) {
 	t.Parallel()
 
-	content := []byte("the whole cached image")
+	svc, fixtures := SetupTestService(t)
 
-	for name, size := range map[string]int64{
-		"empty":   0,
-		"partial": int64(len(content) / 2),
-	} {
-		t.Run(name, func(t *testing.T) {
-			t.Parallel()
+	getImage(t, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
 
-			cache, _ := newEvictionTestCache(t, 1<<30)
+	path := cachedSourcePath(t, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
+	wholeSize := fileSize(t, path)
 
-			sourceKey := storeEvictionTestSource(t, cache, testHostCDN, testPathCat, content)
-			storeEvictionTestVariant(t, cache, testVariantKeyOne, content)
+	truncateFile(t, path, 0)
+	assertWarningNames(t, reconcileAsAtStartup(t, svc.cache), path)
 
-			sourcePath := cache.srcContent.keyToPath(string(sourceKey))
-			variantPath := cache.variants.keyToPath(string(testVariantKeyOne))
+	getImage(t, svc, photoVariant(fixtures, 40, imagerequest.FitCover))
+	getImage(t, svc, photoVariant(fixtures, 30, imagerequest.FitCover))
 
-			for _, path := range []string{sourcePath, variantPath} {
-				err := os.Truncate(path, size)
-				if err != nil {
-					t.Fatalf("cutting %s to %d bytes: %v", path, size, err)
-				}
-			}
+	waitForPendingCountsWritten(t, svc.cache)
 
-			logs := reconcileAsAtStartup(t, cache)
+	fetches := readCacheStatsCounters(t, svc.cache).upstreamFetchCount
+	t.Logf("upstream fetches = %d", fetches)
 
-			assertWarningNames(t, logs, sourcePath)
-			assertWarningNames(t, logs, variantPath)
-
-			_, err := os.Stat(sourcePath)
-			if err == nil {
-				t.Error("the damaged source file is still on disk")
-			}
-
-			_, err = os.Stat(variantPath)
-			if err == nil {
-				t.Error("the damaged variant file is still on disk")
-			}
-
-			rows := countRows(t, cache,
-				`SELECT COUNT(*) FROM source_content WHERE source_key = ?`,
-				string(sourceKey))
-			if rows != 0 {
-				t.Errorf("the damaged source file kept %d rows, want 0", rows)
-			}
-
-			rows = countRows(t, cache,
-				`SELECT COUNT(*) FROM variant_content WHERE cache_key = ?`,
-				string(testVariantKeyOne))
-			if rows != 0 {
-				t.Errorf("the damaged variant file kept %d rows, want 0", rows)
-			}
-		})
+	if fetches != 2 {
+		t.Errorf("upstream fetches = %d, want 2: the empty cached source "+
+			"was kept and fetched again on every new size", fetches)
 	}
+
+	size := fileSize(t, path)
+	if size != wholeSize {
+		t.Errorf("cached source is %d bytes, want %d", size, wholeSize)
+	}
+}
+
+// TestService_Get_FetchesAgainForPartialCachedSource cuts the cached source
+// file to half its size, as a crash or a restored snapshot could, and runs
+// the reconciliation pass, which must remove it with a warning naming it.
+// It then asks for two new sizes of the source: the first must fetch it
+// again rather than fail to decode the partial file, and the second is
+// made from the cache.
+func TestService_Get_FetchesAgainForPartialCachedSource(t *testing.T) {
+	t.Parallel()
+
+	svc, fixtures := SetupTestService(t)
+
+	getImage(t, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
+
+	path := cachedSourcePath(t, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
+	wholeSize := fileSize(t, path)
+
+	truncateFile(t, path, wholeSize/2)
+	assertWarningNames(t, reconcileAsAtStartup(t, svc.cache), path)
+
+	getImage(t, svc, photoVariant(fixtures, 40, imagerequest.FitCover))
+	getImage(t, svc, photoVariant(fixtures, 30, imagerequest.FitCover))
+
+	waitForPendingCountsWritten(t, svc.cache)
+
+	fetches := readCacheStatsCounters(t, svc.cache).upstreamFetchCount
+	t.Logf("upstream fetches = %d", fetches)
+
+	if fetches != 2 {
+		t.Errorf("upstream fetches = %d, want 2", fetches)
+	}
+
+	size := fileSize(t, path)
+	if size != wholeSize {
+		t.Errorf("cached source is %d bytes, want %d", size, wholeSize)
+	}
+}
+
+// assertConvertedAgain caches a variant of the photo, cuts its file to size
+// bytes and runs the reconciliation pass, which must remove it with a
+// warning naming it. It then checks that Get converts the image again
+// instead of serving the file, and that the next Get serves the whole
+// variant from the cache.
+func assertConvertedAgain(t *testing.T, size int64) {
+	t.Helper()
+
+	svc, fixtures := SetupTestService(t)
+	req := photoVariant(fixtures, 85, imagerequest.FitCover)
+
+	want, _ := getImage(t, svc, req)
+
+	path := svc.cache.variants.keyToPath(imagerequest.CacheKey(req))
+
+	truncateFile(t, path, size)
+	assertWarningNames(t, reconcileAsAtStartup(t, svc.cache), path)
+
+	got, status := getImage(t, svc, req)
+	t.Logf("after the cut: %d bytes, %s", len(got), status)
+
+	if status != CacheMiss || !bytes.Equal(got, want) {
+		t.Errorf("after the cut: Get() = %d bytes, %s; want the %d bytes "+
+			"converted again, %s", len(got), status, len(want), CacheMiss)
+	}
+
+	got, status = getImage(t, svc, req)
+	t.Logf("next request: %d bytes, %s", len(got), status)
+
+	if status != CacheHit || !bytes.Equal(got, want) {
+		t.Errorf("next request: Get() = %d bytes, %s; want the %d bytes, %s",
+			len(got), status, len(want), CacheHit)
+	}
+}
+
+// TestService_Get_ConvertsAgainForEmptyCachedVariant empties a cached
+// variant file, as a crash or a restored snapshot could, and checks that it
+// is converted again rather than served empty.
+func TestService_Get_ConvertsAgainForEmptyCachedVariant(t *testing.T) {
+	t.Parallel()
+
+	assertConvertedAgain(t, 0)
+}
+
+// TestService_Get_ConvertsAgainForPartialCachedVariant cuts a cached
+// variant file to ten bytes, as a crash or a restored snapshot could, and
+// checks that it is converted again rather than served cut short.
+func TestService_Get_ConvertsAgainForPartialCachedVariant(t *testing.T) {
+	t.Parallel()
+
+	assertConvertedAgain(t, 10)
 }
 
 // TestReconciliationRemovesEmptyVariantFileWithoutRow checks that the
@@ -118,19 +243,16 @@ func TestReconciliationRemovesEmptyVariantFileWithoutRow(t *testing.T) {
 
 	cache, _ := newEvictionTestCache(t, 1<<30)
 
-	err := cache.variants.Write(string(testVariantKeyOne), nil)
+	_, err := cache.variants.Store(testVariantKeyOne, bytes.NewReader(nil))
 	if err != nil {
 		t.Fatalf("failed to store an empty variant file: %v", err)
 	}
 
-	variantPath := cache.variants.keyToPath(string(testVariantKeyOne))
-
 	logs := reconcileAsAtStartup(t, cache)
 
-	assertWarningNames(t, logs, variantPath)
+	assertWarningNames(t, logs, cache.variants.keyToPath(testVariantKeyOne))
 
-	_, err = os.Stat(variantPath)
-	if err == nil {
+	if cache.variants.Exists(testVariantKeyOne) {
 		t.Error("the empty variant file is still on disk")
 	}
 
@@ -142,19 +264,19 @@ func TestReconciliationRemovesEmptyVariantFileWithoutRow(t *testing.T) {
 	}
 }
 
-// TestFileStore_WriteReplacesFileOfAnotherSize checks that a write over a
-// file of another size at the source's path, such as a partial file a crash
-// left, replaces it with the content.
-func TestFileStore_WriteReplacesFileOfAnotherSize(t *testing.T) {
+// TestContentStorage_StoreReplacesFileOfAnotherSize checks that a
+// store over a file of another size at the source's path, such as a
+// partial file a crash left, replaces it with the content.
+func TestContentStorage_StoreReplacesFileOfAnotherSize(t *testing.T) {
 	t.Parallel()
 
-	storage, err := NewFileStore(t.TempDir())
+	storage, err := NewContentStorage(t.TempDir())
 	if err != nil {
-		t.Fatalf("NewFileStore() error = %v", err)
+		t.Fatalf("NewContentStorage() error = %v", err)
 	}
 
 	content := []byte("the whole source image")
-	key := string(imagerequest.Source{Host: testHostCDN, Path: testPathCat}.Key())
+	key := imagerequest.Source{Host: testHostCDN, Path: testPathCat}.Key()
 	path := storage.keyToPath(key)
 
 	err = os.MkdirAll(filepath.Dir(path), StorageDirPerm)
@@ -167,14 +289,14 @@ func TestFileStore_WriteReplacesFileOfAnotherSize(t *testing.T) {
 		t.Fatalf("writing a partial file: %v", err)
 	}
 
-	err = storage.Write(key, content)
+	_, err = storage.Store(key, content)
 	if err != nil {
-		t.Fatalf("Write() error = %v", err)
+		t.Fatalf("Store() error = %v", err)
 	}
 
-	stored, _, err := storage.Open(key)
+	stored, err := storage.Load(key)
 	if err != nil {
-		t.Fatalf("Open() error = %v", err)
+		t.Fatalf("Load() error = %v", err)
 	}
 
 	defer func() { _ = stored.Close() }()

internal/imgcache/pendingaccesstimes.go

@@ -1,160 +0,0 @@
-package imgcache
-
-import (
-	"context"
-	"fmt"
-	"time"
-
-	"sneak.berlin/go/pixa/internal/imagerequest"
-)
-
-// pendingWriteInterval is how often the goroutine
-// StartPendingAccessTimeWrites starts writes the pending access times.
-// SQLite's CURRENT_TIMESTAMP, which an access time is written as, counts
-// whole seconds.
-const pendingWriteInterval = time.Second
-
-// StartPendingAccessTimeWrites starts the goroutine that writes, every
-// pendingWriteInterval, the pending access times in one transaction.
-// Requests only hand these to it, so none waits for the database to record
-// them, and only this goroutine's write ever waits for it. It is a no-op
-// when already started. The goroutine outlives the caller, so it runs with
-// its own context, which StopPendingAccessTimeWrites cancels to tell it to
-// finish.
-func (c *Cache) StartPendingAccessTimeWrites() {
-	if c.pendingAccessTimesCancel != nil {
-		return
-	}
-
-	ctx, cancel := context.WithCancel(context.Background())
-	c.pendingAccessTimesCancel = cancel
-
-	go func() {
-		c.pendingAccessTimeWriteLoop(ctx)
-	}()
-}
-
-// StopPendingAccessTimeWrites tells the goroutine
-// StartPendingAccessTimeWrites started, if it did, to finish, and waits for
-// its write under way to end and for it to return. It then writes the
-// pending access times left, once, so that they are written before the
-// database closes. It waits for all of this at most until ctx ends. When
-// access times are not written, it logs that and returns an error.
-func (c *Cache) StopPendingAccessTimeWrites(ctx context.Context) error {
-	var err error
-
-	if c.pendingAccessTimesCancel != nil {
-		c.pendingAccessTimesCancel()
-
-		select {
-		case <-c.pendingAccessTimesDone:
-		case <-ctx.Done():
-			// The write given up on here may not reach the database:
-			// database/sql closes without waiting for a query, and a write
-			// still waiting for the connection fails when the database
-			// closes. Nothing is written here.
-			err = fmt.Errorf("access times still being written: %w", ctx.Err())
-		}
-	}
-
-	if err == nil {
-		err = c.writePendingAccessTimes(ctx)
-	}
-
-	if err != nil {
-		c.log.Error("access times not written at shutdown", "error", err)
-	}
-
-	return err
-}
-
-// pendingAccessTimeWriteLoop is the body of the goroutine
-// StartPendingAccessTimeWrites starts. Once ctx is cancelled it starts no
-// write and returns, but does not cut off a write under way then. Access
-// times whose write fails are dropped.
-func (c *Cache) pendingAccessTimeWriteLoop(ctx context.Context) {
-	defer close(c.pendingAccessTimesDone)
-
-	ticker := time.NewTicker(pendingWriteInterval)
-	defer ticker.Stop()
-
-	for {
-		select {
-		case <-ctx.Done():
-			return
-		case <-ticker.C:
-		}
-
-		// select picks at random when ctx is cancelled and a tick waits
-		// too.
-		if ctx.Err() != nil {
-			return
-		}
-
-		err := c.writePendingAccessTimes(context.WithoutCancel(ctx))
-		if err != nil {
-			c.log.Warn("failed to write access times", "error", err)
-		}
-	}
-}
-
-// writePendingAccessTimes takes out the variants waiting in
-// pendingVariantAccessTimes and the sources waiting in
-// pendingSourceAccessTimes, and sets their last_accessed_at to now in one
-// transaction, once for each however often it was used. Nothing else takes
-// from those channels while it runs: only the goroutine
-// StartPendingAccessTimeWrites starts calls it, or
-// StopPendingAccessTimeWrites once that goroutine has returned.
-func (c *Cache) writePendingAccessTimes(ctx context.Context) error {
-	variants := make(map[imagerequest.VariantKey]struct{})
-
-	for range len(c.pendingVariantAccessTimes) {
-		variants[<-c.pendingVariantAccessTimes] = struct{}{}
-	}
-
-	sources := make(map[imagerequest.SourceKey]struct{})
-
-	for range len(c.pendingSourceAccessTimes) {
-		sources[<-c.pendingSourceAccessTimes] = struct{}{}
-	}
-
-	accessTimes := len(variants) + len(sources)
-	if accessTimes == 0 {
-		return nil
-	}
-
-	tx, err := c.db.BeginTx(ctx, nil)
-	if err != nil {
-		return fmt.Errorf("failed to write %d access times: %w", accessTimes, err)
-	}
-
-	// Does nothing once the transaction is committed
-	defer func() { _ = tx.Rollback() }()
-
-	for cacheKey := range variants {
-		_, err = tx.ExecContext(ctx, `
-			UPDATE variant_content SET last_accessed_at = CURRENT_TIMESTAMP
-			WHERE cache_key = ?
-		`, string(cacheKey))
-		if err != nil {
-			return fmt.Errorf("failed to write %d access times: %w", accessTimes, err)
-		}
-	}
-
-	for sourceKey := range sources {
-		_, err = tx.ExecContext(ctx, `
-			UPDATE source_content SET last_accessed_at = CURRENT_TIMESTAMP
-			WHERE source_key = ?
-		`, string(sourceKey))
-		if err != nil {
-			return fmt.Errorf("failed to write %d access times: %w", accessTimes, err)
-		}
-	}
-
-	err = tx.Commit()
-	if err != nil {
-		return fmt.Errorf("failed to write %d access times: %w", accessTimes, err)
-	}
-
-	return nil
-}