Build multi-arch docker images

All changes listed below only touch the GH Actions config.
* Dockerize the tests
* Build JSON matrix configuration for multiple archs
* Build and test in parallel for multiple archs
* Merge the arch-specific images into a single manifest and push at the end

.github/workflows/push.yaml

@@ -5,55 +5,164 @@ on:
   workflow_dispatch:
   push:
 
+env:
+  PLATFORMS: |-
+    linux/amd64
+    linux/arm64
+    linux/arm/v7
+  REGISTRY: ghcr.io
+  IMAGE: ${{ github.repository }}
+
 jobs:
+  generate-matrix:
+    runs-on: ubuntu-latest
+    outputs:
+      matrix: ${{ steps.generate-matrix.outputs.matrix }}
+    steps:
+      - id: generate-matrix
+        shell: bash
+        run: |
+          echo -n "matrix=" >> $GITHUB_OUTPUT
+          # Output a JSON list containing all PLATFORMS
+          echo "${{ env.PLATFORMS }}" | \
+            jq -R -c '[{ platform: . }]' | \
+            jq -n '{ platforms: [ [inputs[0].platform] ] | add}.platforms' -c >> $GITHUB_OUTPUT
+
   test:
+    needs:
+      - generate-matrix
     runs-on: ubuntu-latest
+    strategy:
+      # Use matrix to speed up tests
+      matrix:
+        platform: ${{ fromJSON(needs.generate-matrix.outputs.matrix) }}
 
     steps:
       - uses: actions/checkout@v3
 
-      - uses: actions/setup-go@v3
-        with:
-          go-version: '^1.17.13'
-          cache: true
-
-      - name: Run tests
-        run: go test
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
 
-      - name: Build
-        run: go build
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
 
-  publish_latest:
-    if: github.ref == 'refs/heads/master'
+      - name: Run tests
+        uses: docker/build-push-action@v4
+        with:
+          context: .
+          target: test
+          push: false
+          platforms: ${{ matrix.platform }}
+          # Enable cache to speed up builds
+          # Scope is to ensure that images don't overwrite each other's cache
+          outputs: type=cacheonly
+          cache-from: type=gha,scope=${{ env.REGISTRY }}-${{ github.ref_name }}-${{ matrix.platform }}-tests
+          cache-to: type=gha,mode=max,scope=${{ env.REGISTRY }}-${{ github.ref_name }}-${{ matrix.platform }}-tests
 
+  build:
     runs-on: ubuntu-latest
+    strategy:
+      # Use matrix to speed up builds
+      matrix:
+        platform: ${{ fromJSON(needs.generate-matrix.outputs.matrix) }}
+
     needs:
+      - generate-matrix
       - test
 
     steps:
       - uses: actions/checkout@v3
 
-      - name: publish master to latest
-        uses: macbre/push-to-ghcr@master
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v4
         with:
-          image_name: ${{ github.repository }}
-          github_token: ${{ secrets.GITHUB_TOKEN }}
-          image_tag: latest
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE }}
 
-  publish_release:
-    if: startsWith(github.ref, 'refs/tags/v')
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
 
-    runs-on: ubuntu-latest
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
 
+      - name: Login to Container Registry
+        uses: docker/login-action@v2
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push by digest
+        id: build
+        uses: docker/build-push-action@v4
+        with:
+          context: .
+          platforms: ${{ matrix.platform }}
+          labels: ${{ steps.meta.outputs.labels }}
+          outputs: type=image,name=${{ env.REGISTRY }}/${{ env.IMAGE }},push-by-digest=true,name-canonical=true,push=true
+          # Enable cache to speed up builds
+          # Scope is to ensure that images don't overwrite each other's cache
+          cache-from: type=gha,scope=${{ env.REGISTRY }}-${{ github.ref_name }}-${{ matrix.platform }}-executable
+          cache-to: type=gha,mode=max,scope=${{ env.REGISTRY }}-${{ github.ref_name }}-${{ matrix.platform }}-executable
+
+      - name: Export digest
+        run: |
+          mkdir -p /tmp/digests
+          digest="${{ steps.build.outputs.digest }}"
+          touch "/tmp/digests/${digest#sha256:}"
+
+      - name: Upload digest
+        uses: actions/upload-artifact@v3
+        with:
+          name: digests
+          path: /tmp/digests/*
+          if-no-files-found: error
+          retention-days: 1
+
+
+  merge_and_publish:
+    if: (github.ref == 'refs/heads/master') || (startsWith(github.ref, 'refs/tags/'))
+    runs-on: ubuntu-latest
     needs:
-      - test
+      - build
 
     steps:
-      - uses: actions/checkout@v3
+      - name: Download digests
+        uses: actions/download-artifact@v3
+        with:
+          name: digests
+          path: /tmp/digests
 
-      - name: publish release to tag
-        uses: macbre/push-to-ghcr@master
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v4
         with:
-          image_name: ${{ github.repository }}
-          github_token: ${{ secrets.GITHUB_TOKEN }}
-          image_tag: ${{ github.ref_name }}
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE }}
+          tags: |
+            # tag tags with :tag
+            type=ref,event=tag
+            # tag default branch with :latest
+            type=raw,value=latest,enable={{is_default_branch}}
+          flavor: |
+            # Do not tag tags with :latest
+            latest=false
+
+      - name: Login to Container Registry
+        uses: docker/login-action@v2
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Create manifest list and push
+        working-directory: /tmp/digests
+        run: |
+          docker buildx imagetools create $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
+            $(printf '${{ env.REGISTRY }}/${{ env.IMAGE }}@sha256:%s ' *)
+
+      - name: Inspect image
+        run: |
+          docker buildx imagetools inspect ${{ env.REGISTRY }}/${{ env.IMAGE }}:${{ steps.meta.outputs.version }}

README.md

@@ -32,7 +32,7 @@ Then start its systemd service: `# systemctl start pacoloco`.
 Pacoloco can be used with docker.
 
 You can get a prebuilt image from GitHub's [container registry](https://github.com/anatol/pacoloco/pkgs/container/pacoloco) (see also sidebar).
-Currently only amd64 is supported.
+Currently the images are built for `amd64` and ARM (`arm64`, `armv7`) architectures.
 ```sh
 docker pull ghcr.io/anatol/pacoloco
 ```