A prebuilt image for amd64 and arm64, and the container no longer runs as root

Until now `docker compose up` built the image on the user's machine:
a compiler toolchain, every dev dependency, a few minutes of CPU — on a
Raspberry Pi considerably more. The compose files now pull
ghcr.io/tillheidrich/klarbild:1, built by .github/workflows/image.yml
for linux/amd64 and linux/arm64. `:1` follows every 1.x release, so an
update is `docker compose pull && docker compose up -d`. `build: .` is
one commented line away for anyone who prefers to build.

The Dockerfile has two stages now. The runtime stage carries the built
server, production dependencies and the migrations — no compiler, no
dev dependencies, no source tree. argon2 and sharp ship prebuilt
binaries for both architectures, so python/make/g++ are gone entirely.
It runs as the `node` user (uid 1000); a fresh named volume at /data
inherits that ownership.

Verified locally: image builds, boots against Postgres, applies all 17
migrations, prints the first-run password, passes its healthcheck,
accepts an upload as the unprivileged user and returns an A4 sheet that
measures 210.00 x 297.00 mm.

.dockerignore

@@ -5,3 +5,8 @@ dist
 *.log
 .env
 # Do NOT ignore migrations/ — they are read at runtime, on every boot.
+docs
+tests
+.github
+*.md
+!README.md

.github/workflows/image.yml

@@ -0,0 +1,62 @@
+name: Container image
+
+# Builds the image that docker-compose.yaml pulls, for amd64 and arm64
+# (a Raspberry Pi 4/5 or an ARM VPS runs the same image).
+#
+#   push to main   -> ghcr.io/tillheidrich/klarbild:edge
+#   tag v1.2.3     -> :1.2.3, :1.2, :1 and :latest
+#
+# Nothing to configure: the workflow pushes with its own GITHUB_TOKEN.
+
+on:
+  push:
+    branches: [main]
+    tags: ['v*.*.*']
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  packages: write
+
+concurrency:
+  group: image-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  image:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+
+      - uses: docker/setup-qemu-action@v3
+      - uses: docker/setup-buildx-action@v3
+
+      - uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ghcr.io/${{ github.repository_owner }}/klarbild
+          tags: |
+            type=edge,branch=main
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}}
+          labels: |
+            org.opencontainers.image.title=Klarbild
+            org.opencontainers.image.description=Self-hosted print studio: pictures on paper at exactly the size you asked for.
+            org.opencontainers.image.licenses=AGPL-3.0-only
+
+      - uses: docker/build-push-action@v6
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max

Dockerfile

@@ -1,22 +1,34 @@
-FROM node:22-bookworm-slim
+# Klarbild — two stages. The first builds, the second only runs: no compiler,
+# no dev dependencies, no source tree in the image that ends up on your server.
 
+FROM node:22-bookworm-slim AS build
 WORKDIR /app
-ENV NODE_ENV=production PORT=4321 HOST=0.0.0.0
-
-# Build tools for the native modules (argon2). sharp ships a prebuilt libvips.
-RUN apt-get update && apt-get install -y --no-install-recommends \
-      python3 make g++ ca-certificates \
-    && rm -rf /var/lib/apt/lists/*
-
 # The lockfile comes first and `npm ci` honours it, so the image is built from
 # the exact versions CI tested — not from whatever `^` resolved to today.
+# Native modules (argon2, sharp) ship prebuilt binaries for amd64 and arm64,
+# so no compiler is needed in either stage.
 COPY package.json package-lock.json ./
 RUN npm ci --no-audit --no-fund
-
 COPY . .
-RUN npm run build
+RUN npm run build && npm prune --omit=dev --no-audit --no-fund
+
+FROM node:22-bookworm-slim
+WORKDIR /app
+ENV NODE_ENV=production PORT=4321 HOST=0.0.0.0 STORAGE_DIR=/data
+
+COPY --from=build --chown=node:node /app/package.json ./
+COPY --from=build --chown=node:node /app/node_modules ./node_modules
+COPY --from=build --chown=node:node /app/dist ./dist
+# Read at runtime, on every boot.
+COPY --from=build --chown=node:node /app/migrations ./migrations
+
+# Not root. A fresh named volume mounted at /data takes over this ownership;
+# for a bind mount, give the directory to uid 1000 (`chown 1000:1000 ./data`).
+RUN mkdir -p /data && chown node:node /data
+USER node
 
 EXPOSE 4321
+VOLUME ["/data"]
 
 HEALTHCHECK --interval=30s --timeout=5s --start-period=40s --retries=3 \
   CMD node -e "fetch('http://127.0.0.1:'+(process.env.PORT||4321)+'/api/health').then(r=>process.exit(r.ok?0:1)).catch(()=>process.exit(1))"

docker-compose.full.yaml

@@ -9,9 +9,11 @@
 
 services:
   app:
-    build:
+    # The prebuilt image (amd64 and arm64). `:1` follows every 1.x release, so
-      context: .
+    # `docker compose pull && docker compose up -d` is the whole update.
-      dockerfile: Dockerfile
+    image: ghcr.io/tillheidrich/klarbild:${KLARBILD_VERSION:-1}
+    # Rather build it yourself from this checkout? Swap the line above for:
+    # build: .
     environment:
       PORT: "4321"
       DATABASE_URL: "postgres://klarbild:${DB_PASSWORD:?set DB_PASSWORD in .env}@db:5432/klarbild"

docker-compose.yaml

@@ -1,6 +1,6 @@
 # Klarbild — the default stack: the print studio and a database. That is all.
 #
-#   cp .env.example .env     # fill in the three secrets at the top
+#   cp .env.example .env     # fill in the values at the top; the file says which
 #   docker compose up -d
 #   docker compose logs app  # the first-start password is printed once, here
 #
@@ -9,9 +9,11 @@
 
 services:
   app:
-    build:
+    # The prebuilt image (amd64 and arm64). `:1` follows every 1.x release, so
-      context: .
+    # `docker compose pull && docker compose up -d` is the whole update.
-      dockerfile: Dockerfile
+    image: ghcr.io/tillheidrich/klarbild:${KLARBILD_VERSION:-1}
+    # Rather build it yourself from this checkout? Swap the line above for:
+    # build: .
     environment:
       PORT: "4321"
       DATABASE_URL: "postgres://klarbild:${DB_PASSWORD:?set DB_PASSWORD in .env}@db:5432/klarbild"