ci: add github action to publish a docker image for each new release

Author: Maistho

.github/workflows/docker-publish.yml

@@ -0,0 +1,141 @@
+name: Docker Publish
+
+on:
+  release:
+    types: [published]
+  workflow_dispatch:
+
+concurrency:
+  group: docker-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  prepare:
+    runs-on: ubuntu-24.04
+
+    outputs:
+      image: ${{ steps.image.outputs.name }}
+      labels: ${{ steps.meta.outputs.labels }}
+      json: ${{ steps.meta.outputs.json }}
+
+    steps:
+      - name: Define image name
+        id: image
+        run: echo "name=ghcr.io/${GITHUB_REPOSITORY,,}" >> "$GITHUB_OUTPUT"
+
+      - name: Extract Docker metadata
+        id: meta
+        uses: docker/metadata-action@v6
+        with:
+          images: ${{ steps.image.outputs.name }}
+          tags: |
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}}
+            type=raw,value=latest,enable=${{ github.event_name == 'release' }}
+            type=sha,prefix=sha-,enable=${{ github.event_name == 'workflow_dispatch' }}
+
+  build:
+    needs: prepare
+    runs-on: ${{ matrix.runner }}
+
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - platform: linux/amd64
+            platform-id: linux-amd64
+            runner: ubuntu-24.04
+          - platform: linux/arm64
+            platform-id: linux-arm64
+            runner: ubuntu-24.04-arm
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v4
+
+      - name: Log in to GitHub Container Registry
+        uses: docker/login-action@v4
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push Docker image by digest
+        id: build
+        uses: docker/build-push-action@v7
+        with:
+          context: .
+          platforms: ${{ matrix.platform }}
+          push: true
+          labels: ${{ needs.prepare.outputs.labels }}
+          outputs: type=image,name=${{ needs.prepare.outputs.image }},name-canonical=true,push-by-digest=true,push=true
+          cache-from: type=gha,scope=${{ matrix.platform-id }}
+          cache-to: type=gha,mode=max,scope=${{ matrix.platform-id }}
+
+      - name: Export image digest
+        run: |
+          mkdir -p /tmp/digests
+          digest="${{ steps.build.outputs.digest }}"
+          touch "/tmp/digests/${digest#sha256:}"
+
+      - name: Upload image digest
+        uses: actions/upload-artifact@v4
+        with:
+          name: digest-${{ matrix.platform-id }}
+          path: /tmp/digests/*
+          if-no-files-found: error
+          retention-days: 1
+
+  merge:
+    needs:
+      - prepare
+      - build
+    runs-on: ubuntu-24.04
+
+    steps:
+      - name: Download image digests
+        uses: actions/download-artifact@v4
+        with:
+          path: /tmp/digests
+          pattern: digest-*
+          merge-multiple: true
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v4
+
+      - name: Log in to GitHub Container Registry
+        uses: docker/login-action@v4
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Create multi-platform manifest
+        env:
+          DOCKER_METADATA_OUTPUT_JSON: ${{ needs.prepare.outputs.json }}
+          IMAGE_NAME: ${{ needs.prepare.outputs.image }}
+        run: |
+          cd /tmp/digests
+          # Build the list of digest references
+          digest_refs=""
+          for digest in *; do
+            digest_refs="$digest_refs $IMAGE_NAME@sha256:$digest"
+          done
+          # Create the manifest
+          docker buildx imagetools create \
+            $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
+            $digest_refs
+
+      - name: Inspect published image
+        env:
+          DOCKER_METADATA_OUTPUT_JSON: ${{ needs.prepare.outputs.json }}
+        run: |
+          docker buildx imagetools inspect "$(jq -r '.tags[0]' <<< "$DOCKER_METADATA_OUTPUT_JSON")"

AGENTS.md

@@ -99,6 +99,7 @@ See: [`.github/workflows/`](./.github/workflows/)
 - [`dotnet.yml`](./.github/workflows/dotnet.yml): Main .NET build and test pipeline.
 - [`codeql.yml`](./.github/workflows/codeql.yml): Security scanning.
 - [`localization.yml`](./.github/workflows/localization.yml): Localization checks.
+- [`docker-publish.yml`](./.github/workflows/docker-publish.yml): Builds and publishes multi-arch container images to GHCR on every published release.
 
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