ci: add docker image workflow

.github/workflows/docker-publish.yml

@@ -0,0 +1,76 @@
+name: Build and publish Docker image
+
+on:
+  push:
+    branches: [dev]
+    tags:
+      - '+([0-9]).+([0-9]).+([0-9])'
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+      attestations: write
+      artifact-metadata: write
+      id-token: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: Log in to GitHub Container Registry
+        uses: docker/login-action@c94ce9fb468520275223c153574b00df6fe4bcc9 # v3.7.0
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata
+        id: meta
+        uses: docker/metadata-action@c299e40c65443455700f0fdfc63efafe5b349051 # v5.10.0
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          flavor: |
+            latest=false
+          tags: |
+            # dev branch: short commit SHA + latest
+            type=sha,prefix=,format=short,enable=${{ github.ref == 'refs/heads/dev' }}
+            type=raw,value=latest,enable=${{ github.ref == 'refs/heads/dev' }}
+
+            # git tags: semver breakdown
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}},enable=${{ !startsWith(github.ref, 'refs/tags/0.') }}
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@c7c53464625b32c7a7e944ae62b3e17d2b600130 # v3.7.0
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f # v3.12.0
+
+      - name: Build and push Docker image
+        id: push
+        uses: docker/build-push-action@10e90e3645eae34f1e60eeb005ba3a3d33f178e8 # v6.19.2
+        with:
+          context: .
+          push: true
+          platforms: linux/amd64,linux/arm64,linux/arm/v7
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+
+      - name: Generate artifact attestation
+        uses: actions/attest-build-provenance@a2bbfa25375fe432b6a289bc6b6cd05ecd0c4c32 # v4.1.0
+        with:
+          subject-name: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          subject-digest: ${{ steps.push.outputs.digest }}
+          push-to-registry: true

README.md

@@ -12,7 +12,41 @@ The web app is available at [app.sable.moe](https://app.sable.moe/) and gets upd
 You can also download our desktop app for windows and linux from [releases](https://github.com/7w1/sable/releases/latest).
 
 ## Self-hosting
-To host Sable on your own, download this repo and built with nginx.
+You can either run the prebuilt container image or build Sable yourself.
+
+### Docker
+
+Prebuilt images are published to `ghcr.io/7w1/sable`.
+
+- `latest` tracks the current `dev` branch image.
+- `X.Y.Z` tags are versioned releases.
+- `X.Y` tags float within a release line.
+- Pushes to `dev` also publish a short commit SHA tag.
+
+Run the latest image with:
+
+```sh
+docker run --rm -p 8080:80 ghcr.io/7w1/sable:latest
+```
+
+Then open `http://localhost:8080`.
+
+If you want to override the bundled [`config.json`](config.json), mount your own
+file at `/app/config.json`:
+
+```yaml
+services:
+  sable:
+    image: ghcr.io/7w1/sable:latest
+    ports:
+      - '8080:80'
+    volumes:
+      - ./config.json:/app/config.json:ro
+```
+
+### Build it yourself
+
+To build and serve Sable yourself with nginx, clone this repo and build it:
 
 ```sh
 npm ci # Installs all dependencies