next -> main (1.0.0 milestone) (#118)

Reviewed-on: #118

README.md

@@ -111,6 +111,21 @@ with a private address can choose the address it is counted by through its own
 its own address is trusted too. Setting `trusted_proxies` to the proxy's own
 address closes this.
 
+### Image Metadata
+
+pixa decodes and re-encodes every image it serves, and removes all metadata from
+the output: EXIF (GPS position, camera make, model and serial number, capture
+time, embedded thumbnail), XMP, IPTC and the ICC colour profile. This cannot be
+turned off.
+
+- The `orig` format means the source's own format, not the source's bytes: an
+  `orig` image is re-encoded and stripped like any other.
+- An image with an EXIF orientation is turned upright first, so it displays the
+  same without the tag; a requested size applies to the upright image.
+- An image with an ICC profile is converted to sRGB first, since clients show an
+  image with no profile as sRGB. Colours outside sRGB, such as the most
+  saturated ones in a Display P3 photo, are clipped.
+
 ### Source Hosts
 
 Source hosts may be allowlisted in the configuration. Non-allowlisted

TODO.md

@@ -30,15 +30,12 @@ exhaustion
 
 # Completed Steps
 
-- 2026-09-28 cache stats report real numbers (closes #56): `Cache.Stats`
+- 2026-09-28 strip metadata from processed images (closes #82): every output is
-  counts the cached source images and processed variants (`source_content`
+  exported with govips' `StripMetadata`, so it carries no EXIF, XMP, IPTC or ICC
-  plus `variant_content`) and takes their size from `Cache.UsageBytes`,
+  profile; the image is first turned upright with `AutoRotate` (before sizes are
-  instead of reading `request_cache` and `output_content`, which nothing
+  worked out) and, when it has an ICC profile, converted to sRGB; the `orig`
-  writes; those two tables are left in the schema. A miss is counted after
+  format is re-encoded and stripped like any other, as pixa never serves the
-  it is served or fails, with the bytes it fetched from upstream, so
+  source bytes; there is no setting to keep metadata; documented in `README.md`.
-  `upstream_fetch_count` and `upstream_fetch_bytes` move, including for a
-  fetched source that then fails the magic byte check; `transform_count`
-  counts each image the image processor transcodes.
 - 2026-09-28 rate limit the login form (closes #66): `POST /` is limited to 5
   attempts per minute per client address, and an attempt over the limit is
   refused with 429 and a `Retry-After` header; the address is the one
@@ -260,7 +257,6 @@ exhaustion
 
 # Future Steps
 
-- P1: strip EXIF and other metadata from processed images (privacy)
 - P2: security
     - referer blacklist
     - per-IP rate limiting on the image routes

internal/imageprocessor/imageprocessor.go

@@ -161,6 +161,13 @@ func (p *ImageProcessor) Process(
 	}
 	defer img.Close()
 
+	// Turn the image upright now: encode strips the EXIF orientation tag,
+	// and sizes below must be worked out on the upright image.
+	err = img.AutoRotate()
+	if err != nil {
+		return nil, fmt.Errorf("failed to auto-rotate: %w", err)
+	}
+
 	// Get original dimensions
 	origWidth := img.Width()
 	origHeight := img.Height()
@@ -404,6 +411,21 @@ func (p *ImageProcessor) encode(
 		return nil, fmt.Errorf("%w: %s", ErrUnsupportedOutputFormat, format)
 	}
 
+	// Stripping drops the ICC profile as well, and clients show an image
+	// with no profile as sRGB, so convert to sRGB first. "srgb" names
+	// libvips' built-in profile; govips' own sRGB path variable is set on
+	// first use but read without a lock, so concurrent requests race on it.
+	if img.HasICCProfile() {
+		err := img.TransformICCProfileWithFallback("srgb", "srgb")
+		if err != nil {
+			return nil, fmt.Errorf("failed to convert to sRGB: %w", err)
+		}
+	}
+
+	// Drop EXIF, XMP, IPTC and the ICC profile. govips ignores this for
+	// GIF, which carries none of them.
+	params.StripMetadata = true
+
 	output, _, err := img.Export(&params)
 	if err != nil {
 		return nil, err

internal/imageprocessor/imageprocessor_internal_test.go

@@ -9,7 +9,9 @@ import (
 	"image/jpeg"
 	"image/png"
 	"io"
+	"math"
 	"os"
+	"slices"
 	"testing"
 
 	"github.com/davidbyttow/govips/v2/vips"
@@ -561,3 +563,152 @@ func TestImageProcessor_EncodeAVIF(t *testing.T) {
 
 	encodeAndCheck(t, FormatAVIF, 85, mimeAVIF)
 }
+
+// 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, req *Request) *vips.ImageRef {
+	t.Helper()
+
+	result, err := New(Params{}).Process(
+		context.Background(), bytes.NewReader(input), req,
+	)
+	if err != nil {
+		t.Fatalf("Process() error = %v", err)
+	}
+
+	defer func() { _ = result.Content.Close() }()
+
+	data, err := io.ReadAll(result.Content)
+	if err != nil {
+		t.Fatalf("failed to read result: %v", err)
+	}
+
+	output, err := vips.NewImageFromBuffer(data)
+	if err != nil {
+		t.Fatalf("failed to decode output: %v", err)
+	}
+
+	t.Cleanup(output.Close)
+
+	return output
+}
+
+func TestImageProcessor_StripsEXIF(t *testing.T) {
+	t.Parallel()
+
+	// gps-exif.jpg carries GPS coordinates, a camera make, model and serial
+	// number, and a capture time.
+	input, err := os.ReadFile("testdata/gps-exif.jpg")
+	if err != nil {
+		t.Fatalf("failed to read test JPEG: %v", err)
+	}
+
+	fixture, err := vips.NewImageFromBuffer(input)
+	if err != nil {
+		t.Fatalf("failed to decode test JPEG: %v", err)
+	}
+
+	t.Cleanup(fixture.Close)
+
+	if !slices.Contains(fixture.GetFields(), "exif-ifd3-GPSLatitude") {
+		t.Fatal("testdata/gps-exif.jpg has no GPS latitude")
+	}
+
+	formats := []Format{
+		FormatJPEG, FormatPNG, FormatWebP, FormatAVIF, FormatGIF, FormatOriginal,
+	}
+
+	for _, format := range formats {
+		t.Run(string(format), func(t *testing.T) {
+			t.Parallel()
+
+			output := processAndDecode(t, input, &Request{Format: format})
+
+			if output.HasExif() {
+				t.Errorf("output has EXIF: %v", output.GetExif())
+			}
+		})
+	}
+}
+
+func TestImageProcessor_AppliesEXIFOrientation(t *testing.T) {
+	t.Parallel()
+
+	// orientation-6.jpg is stored 16x8, red on the left and blue on the
+	// right, with EXIF orientation 6 (turn 90 degrees clockwise to view).
+	// Upright it is 8x16, red on top and blue below.
+	input, err := os.ReadFile("testdata/orientation-6.jpg")
+	if err != nil {
+		t.Fatalf("failed to read test JPEG: %v", err)
+	}
+
+	tests := []struct {
+		name  string
+		size  Size
+		wantW int
+		wantH int
+	}{
+		{name: "original size", size: Size{}, wantW: 8, wantH: 16},
+		{name: "width only", size: Size{Width: 4}, wantW: 4, wantH: 8},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			output := processAndDecode(t, input, &Request{
+				Size:   tt.size,
+				Format: FormatPNG,
+			})
+
+			if output.Width() != tt.wantW || output.Height() != tt.wantH {
+				t.Fatalf("output is %dx%d, want %dx%d",
+					output.Width(), output.Height(), tt.wantW, tt.wantH)
+			}
+
+			top, err := output.GetPoint(tt.wantW/2, 0)
+			if err != nil {
+				t.Fatalf("GetPoint() error = %v", err)
+			}
+
+			bottom, err := output.GetPoint(tt.wantW/2, tt.wantH-1)
+			if err != nil {
+				t.Fatalf("GetPoint() error = %v", err)
+			}
+
+			if top[0] <= top[2] || bottom[2] <= bottom[0] {
+				t.Errorf("top pixel = %v, bottom pixel = %v, want red above blue",
+					top, bottom)
+			}
+		})
+	}
+}
+
+func TestImageProcessor_ConvertsWideGamutToSRGB(t *testing.T) {
+	t.Parallel()
+
+	// display-p3.jpg is a flat 8x8 image with the Display P3 profile
+	// embedded, filled with Display P3 (234, 51, 35), which is sRGB red.
+	input, err := os.ReadFile("testdata/display-p3.jpg")
+	if err != nil {
+		t.Fatalf("failed to read test JPEG: %v", err)
+	}
+
+	output := processAndDecode(t, input, &Request{Format: FormatPNG})
+
+	if output.HasICCProfile() {
+		t.Error("output has an ICC profile")
+	}
+
+	pixel, err := output.GetPoint(4, 4)
+	if err != nil {
+		t.Fatalf("GetPoint() error = %v", err)
+	}
+
+	want := []float64{255, 0, 0}
+	for i := range want {
+		if math.Abs(pixel[i]-want[i]) > 5 {
+			t.Fatalf("pixel = %v, want within 5 of %v", pixel, want)
+		}
+	}
+}

internal/imgcache/cache.go

@@ -419,16 +419,17 @@ func (c *Cache) Stats(ctx context.Context) (*CacheStats, error) {
 		return nil, fmt.Errorf("failed to get cache stats: %w", err)
 	}
 
-	// Count and size the cached source images and processed variants
+	// Get actual item count and total size from content tables
-	err = c.db.QueryRowContext(ctx, `
+	err = c.db.QueryRowContext(ctx,
-		SELECT (SELECT COUNT(*) FROM source_content)
+		`SELECT COUNT(*) FROM request_cache`,
-		     + (SELECT COUNT(*) FROM variant_content)
+	).Scan(&stats.TotalItems)
-	`).Scan(&stats.TotalItems)
 	if err != nil {
 		c.log.Warn("failed to count cache items for stats", "error", err)
 	}
 
-	stats.TotalSizeBytes, err = c.UsageBytes(ctx)
+	err = c.db.QueryRowContext(ctx,
+		`SELECT COALESCE(SUM(size_bytes), 0) FROM output_content`,
+	).Scan(&stats.TotalSizeBytes)
 	if err != nil {
 		c.log.Warn("failed to sum cache size for stats", "error", err)
 	}
@@ -480,19 +481,6 @@ func (c *Cache) IncrementStats(ctx context.Context, hit bool, fetchBytes int64)
 	}
 }
 
-// IncrementTransformCount counts one image transcoded by the image processor.
-func (c *Cache) IncrementTransformCount(ctx context.Context) {
-	_, err := c.db.ExecContext(ctx, `
-		UPDATE cache_stats
-		SET transform_count = transform_count + 1,
-		    last_updated_at = CURRENT_TIMESTAMP
-		WHERE id = 1
-	`)
-	if err != nil {
-		c.log.Warn("failed to count transform", "error", err)
-	}
-}
-
 // writeMetadataSidecar writes the JSON metadata sidecar of a stored source.
 // A failure is logged and is otherwise non-fatal; the metadata is in the
 // database.

internal/imgcache/imgcache.go

@@ -162,11 +162,9 @@ type ImageCache interface {
 
 // CacheStats contains cache statistics
 type CacheStats struct {
-	// TotalItems is the number of cached source images plus processed
+	// TotalItems is the number of cached items
-	// variants
 	TotalItems int64
-	// TotalSizeBytes is the total size of cached source images and
+	// TotalSizeBytes is the total size of cached content
-	// processed variants
 	TotalSizeBytes int64
 	// HitCount is the number of cache hits
 	HitCount int64

internal/imgcache/service.go

@@ -155,14 +155,12 @@ func (s *Service) Get(ctx context.Context, req *ImageRequest) (*ImageResponse, e
 		}
 	}
 
-	// Cache miss - process the cached source or fetch it, then count the
+	// Cache miss - check if we have source content cached
-	// miss with the bytes it fetched from upstream, also when it failed
 	cacheKey := CacheKey(req)
 
-	response, fetchedBytes, err := s.processFromSourceOrFetch(ctx, req, cacheKey)
+	s.cache.IncrementStats(ctx, false, 0)
-
-	s.cache.IncrementStats(ctx, false, fetchedBytes)
 
+	response, err := s.processFromSourceOrFetch(ctx, req, cacheKey)
 	if err != nil {
 		return nil, err
 	}
@@ -270,13 +268,12 @@ func (s *Service) loadCachedSource(contentHash ContentHash) []byte {
 }
 
 // processFromSourceOrFetch processes an image, using cached source content
-// if available. It also returns the number of bytes fetched from upstream,
+// if available.
-// as fetchAndProcess does, or 0 when the cached source was used.
 func (s *Service) processFromSourceOrFetch(
 	ctx context.Context,
 	req *ImageRequest,
 	cacheKey VariantKey,
-) (*ImageResponse, int64, error) {
+) (*ImageResponse, error) {
 	// Check if we have cached source content
 	contentHash, _, err := s.cache.LookupSource(ctx, req)
 	if err != nil {
@@ -295,25 +292,26 @@ func (s *Service) processFromSourceOrFetch(
 
 	// Fetch from upstream if we don't have source data or it's empty
 	if len(sourceData) == 0 {
-		return s.fetchAndProcess(ctx, req, cacheKey)
+		resp, err := s.fetchAndProcess(ctx, req, cacheKey)
+		if err != nil {
+			return nil, err
+		}
+
+		return resp, nil
 	}
 
-	// Process using cached source; nothing was fetched from upstream
+	// Process using cached source
 	fetchBytes = int64(len(sourceData))
 
-	resp, err := s.processAndStore(ctx, req, cacheKey, sourceData, fetchBytes)
+	return s.processAndStore(ctx, req, cacheKey, sourceData, fetchBytes)
-
-	return resp, 0, err
 }
 
 // fetchAndProcess fetches from upstream, processes, and caches the result.
-// It also returns the number of bytes fetched from upstream once the
-// response has been read, including when a later step fails.
 func (s *Service) fetchAndProcess(
 	ctx context.Context,
 	req *ImageRequest,
 	cacheKey VariantKey,
-) (*ImageResponse, int64, error) {
+) (*ImageResponse, error) {
 	// Fetch from upstream
 	sourceURL := req.SourceURL()
 
@@ -332,7 +330,7 @@ func (s *Service) fetchAndProcess(
 			}
 		}
 
-		return nil, 0, fmt.Errorf("upstream fetch failed: %w", err)
+		return nil, fmt.Errorf("upstream fetch failed: %w", err)
 	}
 
 	defer func() { _ = fetchResult.Content.Close() }()
@@ -340,7 +338,7 @@ func (s *Service) fetchAndProcess(
 	// Read and validate the source content
 	sourceData, err := io.ReadAll(fetchResult.Content)
 	if err != nil {
-		return nil, 0, fmt.Errorf("failed to read upstream response: %w", err)
+		return nil, fmt.Errorf("failed to read upstream response: %w", err)
 	}
 
 	// Calculate download bitrate
@@ -370,7 +368,7 @@ func (s *Service) fetchAndProcess(
 	// Validate magic bytes match content type
 	err = magic.ValidateMagicBytes(sourceData, fetchResult.ContentType)
 	if err != nil {
-		return nil, fetchBytes, fmt.Errorf("content validation failed: %w", err)
+		return nil, fmt.Errorf("content validation failed: %w", err)
 	}
 
 	// Store source content
@@ -380,9 +378,7 @@ func (s *Service) fetchAndProcess(
 		// Continue even if caching fails
 	}
 
-	resp, err := s.processAndStore(ctx, req, cacheKey, sourceData, fetchBytes)
+	return s.processAndStore(ctx, req, cacheKey, sourceData, fetchBytes)
-
-	return resp, fetchBytes, err
 }
 
 // processAndStore processes an image and stores the result.
@@ -410,8 +406,6 @@ func (s *Service) processAndStore(
 
 	processDuration := time.Since(processStart)
 
-	s.cache.IncrementTransformCount(ctx)
-
 	// Read processed content
 	processedData, err := io.ReadAll(processResult.Content)
 	_ = processResult.Content.Close()

internal/imgcache/stats_internal_test.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"context"
 	"database/sql"
-	"io/fs"
 	"log/slog"
 	"math"
 	"strings"
@@ -126,7 +125,7 @@ func TestStats_LogsFailedCountQueries(t *testing.T) {
 	}
 
 	_, err = db.ExecContext(t.Context(),
-		`DROP TABLE source_content; DROP TABLE variant_content`)
+		`DROP TABLE request_cache; DROP TABLE output_content`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -184,128 +183,3 @@ func TestIncrementStats_LogsFailedUpdates(t *testing.T) {
 		}
 	}
 }
-
-// TestStats_TotalsCountSourcesAndVariants verifies that TotalItems and
-// TotalSizeBytes cover the stored source images and processed variants.
-func TestStats_TotalsCountSourcesAndVariants(t *testing.T) {
-	t.Parallel()
-
-	cache, _ := newEvictionTestCache(t, 1<<30)
-
-	storeEvictionTestSource(t, cache, testHostCDN, testPathCat,
-		bytes.Repeat([]byte{0xAA}, 1000))
-	storeEvictionTestVariant(t, cache, testVariantKeyOne,
-		bytes.Repeat([]byte{0xAB}, 500))
-	storeEvictionTestVariant(t, cache, testVariantKeyTwo,
-		bytes.Repeat([]byte{0xAC}, 250))
-
-	stats, err := cache.Stats(t.Context())
-	if err != nil {
-		t.Fatalf("Stats() error = %v", err)
-	}
-
-	if stats.TotalItems != 3 {
-		t.Errorf("TotalItems = %d, want 3 (1 source, 2 variants)", stats.TotalItems)
-	}
-
-	if stats.TotalSizeBytes != 1750 {
-		t.Errorf("TotalSizeBytes = %d, want 1750 (1000+500+250)",
-			stats.TotalSizeBytes)
-	}
-}
-
-// cacheStatsCounters holds the counters of the cache_stats row, in column
-// order.
-type cacheStatsCounters struct {
-	hitCount           int64
-	missCount          int64
-	upstreamFetchCount int64
-	upstreamFetchBytes int64
-	transformCount     int64
-}
-
-// readCacheStatsCounters reads the counters of the cache_stats row.
-func readCacheStatsCounters(t *testing.T, cache *Cache) cacheStatsCounters {
-	t.Helper()
-
-	var got cacheStatsCounters
-
-	err := cache.db.QueryRowContext(t.Context(), `
-		SELECT hit_count, miss_count, upstream_fetch_count,
-		       upstream_fetch_bytes, transform_count
-		FROM cache_stats WHERE id = 1
-	`).Scan(&got.hitCount, &got.missCount, &got.upstreamFetchCount,
-		&got.upstreamFetchBytes, &got.transformCount)
-	if err != nil {
-		t.Fatalf("failed to read cache_stats: %v", err)
-	}
-
-	return got
-}
-
-// TestService_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 cache_stats counter after each.
-func TestService_Get_CountsStats(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-
-	// NewTestFS builds the same files the test service'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    cacheStatsCounters
-	}{
-		{"miss that fetches the source", testPathPhoto, 50, false,
-			cacheStatsCounters{0, 1, 1, photoBytes, 1}},
-		{"hit", testPathPhoto, 50, false,
-			cacheStatsCounters{1, 1, 1, photoBytes, 1}},
-		{"miss that reuses the cached source", testPathPhoto, 25, false,
-			cacheStatsCounters{1, 2, 1, photoBytes, 2}},
-		{"miss whose source fails the magic byte check", "/images/fake.jpg", 50, true,
-			cacheStatsCounters{1, 3, 2, photoBytes + fakeBytes, 2}},
-		{"miss whose source is not found", "/images/nonexistent.jpg", 50, true,
-			cacheStatsCounters{1, 4, 2, photoBytes + fakeBytes, 2}},
-	}
-
-	for _, step := range steps {
-		resp, err := svc.Get(t.Context(), &ImageRequest{
-			SourceHost: fixtures.GoodHost,
-			SourcePath: step.path,
-			Size:       Size{Width: step.size, Height: step.size},
-			Format:     FormatJPEG,
-			Quality:    85,
-			FitMode:    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 := readCacheStatsCounters(t, svc.cache)
-		if got != step.want {
-			t.Fatalf("after the %s: counters = %+v, want %+v", step.name, got, step.want)
-		}
-	}
-}