Dockerfile

@@ -22,8 +22,9 @@ FROM golang:1.25.4-alpine@sha256:d3f0cf7723f3429e3f9ed846243970b20a2de7bae6a5b66
 
 WORKDIR /src
 
-# script/bootstrap --cgo installs the build dependencies (a C compiler
-# and the libvips and libheif headers) and downloads the Go modules.
+# script/bootstrap --cgo installs the build dependencies (a C compiler,
+# the libvips and libheif headers, and libvips' JPEG XL support, which
+# the tests need) and downloads the Go modules.
 COPY script/ ./script/
 COPY go.mod go.sum ./
 RUN script/bootstrap --cgo
@@ -80,9 +81,11 @@ RUN version="${VERSION:-$(git describe --tags --always)}"; \
 # alpine:3.21, 2026-02-25
 FROM alpine:3.21@sha256:c3f8e73fdb79deaebaa2037150150191b9dcbfba68b4a46d70103204c53f4709
 
-# Install runtime dependencies only
+# Install runtime dependencies only. vips-jxl is libvips' JPEG XL
+# support, without which pixad does not start.
 RUN apk add --no-cache \
     vips \
+    vips-jxl \
     libheif \
     ca-certificates \
     tzdata \

README.md

@@ -89,7 +89,10 @@ another part of pixa failed to stop. A request not finished by then is cut off.
 `docker stop` waits 10 seconds before it kills the container.
 
 Outside Docker, pixa needs libvips (the image has 8.15) and libheif to run, as
-it uses libvips through CGO; building it also needs their development files,
+it uses libvips through CGO. pixad does not start unless libvips has its JPEG XL
+support, which on Alpine is the `vips-jxl` package and which the nix and brew
+packages of libvips include, as do the apt ones from Debian 12 and Ubuntu 24.04
+on. Building pixa also needs the development files of libvips and libheif,
 `pkg-config` and a C compiler. `script/bootstrap --cgo` installs all of these,
 as the `Dockerfile` does where it compiles pixa. Plain `script/bootstrap`, which
 `script/setup` and `script/cibuild` run, installs git, make and Go, and Node,
@@ -585,8 +588,8 @@ provide:
 
 - `script/bootstrap` — install git, make, Go, Node, Yarn and prettier and
   download the Go modules (idempotent); with `--cgo`, the C compiler and the
-  libvips and libheif libraries that compiling pixa needs instead of Node, Yarn
-  and prettier
+  libvips (with its JPEG XL support) and libheif libraries that compiling and
+  testing pixa need instead of Node, Yarn and prettier
 - `script/setup` — make a fresh clone ready for development (bootstrap, then
   install-precommit)
 - `script/projectname` — output the project name ("pixa")

TODO.md

@@ -30,6 +30,14 @@ P2: security: per-IP rate limiting on the image routes
 
 # Completed Steps
 
+- 2026-10-08 libvips' JPEG XL support is installed and required (part of #222):
+  `script/bootstrap --cgo` installs `vips-jxl` when its package manager is apk,
+  as Alpine's `vips` package lacks the support, and the runtime stage of the
+  `Dockerfile` installs it too. `imgcache.NewService` fails, naming the fix,
+  when `imageprocessor.CheckJPEGXLSupport` finds that libvips cannot load and
+  save JPEG XL, so pixad does not start without it. A test saves an image as
+  JPEG XL with govips and loads it back. JPEG XL is not yet a format pixa
+  serves.
 - 2026-10-08 SQLite writes no longer fail with "database is locked" under load
   (closes #223): `internal/database` opens the database with one connection, so
   pixa's own reads and writes run on it one at a time instead of competing for

internal/imageprocessor/imageprocessor.go

@@ -37,6 +37,24 @@ func initVips() {
 	})
 }
 
+// errNoJPEGXL is returned by CheckJPEGXLSupport.
+var errNoJPEGXL = errors.New("libvips lacks JPEG XL support: install " +
+	"vips-jxl on Alpine, or use a libvips built with libjxl")
+
+// CheckJPEGXLSupport returns an error, naming the fix, when libvips
+// cannot load and save JPEG XL.
+func CheckJPEGXLSupport() error {
+	initVips()
+
+	// govips counts a format as supported when libvips has its loader;
+	// libvips builds the JPEG XL loader and saver together.
+	if !vips.IsTypeSupported(vips.ImageTypeJXL) {
+		return errNoJPEGXL
+	}
+
+	return nil
+}
+
 // Format represents supported output image formats.
 type Format string
 

internal/imageprocessor/jpegxl_internal_test.go

@@ -0,0 +1,52 @@
+package imageprocessor
+
+import (
+	"testing"
+
+	"github.com/davidbyttow/govips/v2/vips"
+)
+
+// TestCheckJPEGXLSupport fails when libvips lacks JPEG XL support, as on
+// Alpine without the vips-jxl package.
+func TestCheckJPEGXLSupport(t *testing.T) {
+	t.Parallel()
+
+	err := CheckJPEGXLSupport()
+	if err != nil {
+		t.Fatalf("CheckJPEGXLSupport() error = %v", err)
+	}
+}
+
+// TestLibvipsSavesAndLoadsJPEGXL saves an image as JPEG XL with govips and
+// loads it back. It fails when libvips lacks JPEG XL support, as on Alpine
+// without the vips-jxl package.
+func TestLibvipsSavesAndLoadsJPEGXL(t *testing.T) {
+	t.Parallel()
+
+	img, err := vips.NewImageFromBuffer(createTestJPEG(t, 64, 48))
+	if err != nil {
+		t.Fatalf("failed to load test JPEG: %v", err)
+	}
+
+	defer img.Close()
+
+	jxl, _, err := img.ExportJxl(vips.NewJxlExportParams())
+	if err != nil {
+		t.Fatalf("ExportJxl() error = %v", err)
+	}
+
+	loaded, err := vips.NewImageFromBuffer(jxl)
+	if err != nil {
+		t.Fatalf("failed to load the JPEG XL image: %v", err)
+	}
+
+	defer loaded.Close()
+
+	if loaded.Format() != vips.ImageTypeJXL {
+		t.Errorf("loaded format = %s, want jxl", vips.ImageTypes[loaded.Format()])
+	}
+
+	if loaded.Width() != 64 || loaded.Height() != 48 {
+		t.Errorf("loaded size = %dx%d, want 64x48", loaded.Width(), loaded.Height())
+	}
+}

internal/imgcache/service.go

@@ -100,6 +100,13 @@ func NewService(cfg *ServiceConfig) (*Service, error) {
 		allowHTTP = cfg.FetcherConfig.AllowHTTP
 	}
 
+	// JPEG XL is to become the default output format, so pixad does not
+	// start without it.
+	err := imageprocessor.CheckJPEGXLSupport()
+	if err != nil {
+		return nil, err
+	}
+
 	maxResponseSize := fetcherCfg.MaxResponseSize
 	processor := imageprocessor.New(imageprocessor.Params{
 		MaxInputBytes:           maxResponseSize,

script/bootstrap

@@ -14,11 +14,12 @@
 #                            script/fmt-check: all the host needs, as
 #                            the checks compile pixa in Docker
 #   script/bootstrap --cgo   git, make, Go, and a C compiler and the
-#                            CGO image libraries (pkg-config, vips,
-#                            libheif) for the govips bindings instead
-#                            of Node: to compile pixa, in the
-#                            Dockerfile's test phase and build stage,
-#                            which format nothing
+#                            CGO image libraries (pkg-config, vips
+#                            with its JPEG XL support, libheif) for
+#                            the govips bindings instead of Node: to
+#                            compile pixa, in the Dockerfile's test
+#                            phase and build stage, which format
+#                            nothing
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
@@ -150,6 +151,16 @@ ensure_cgo_deps() {
     if ! pkg-config --exists vips; then
         pkg_install vips libvips-dev vips vips-dev
     fi
+    # libvips' JPEG XL loader and saver are in the nix and brew vips
+    # packages, and in apt's from Debian 12 and Ubuntu 24.04 on, but in
+    # the package vips-jxl on Alpine. detect_pkgmgr is called only where
+    # apk exists, as on apt it updates the package lists.
+    if ! missing apk; then
+        detect_pkgmgr
+    fi
+    if [ "$PKGMGR" = "apk" ] && ! apk info -e vips-jxl >/dev/null; then
+        apk add --no-cache vips-jxl
+    fi
     if ! pkg-config --exists libheif; then
         pkg_install libheif libheif-dev libheif libheif-dev
     fi