WIP: build on arm when releasing

.github/workflows/release.yml

@@ -23,38 +23,39 @@ jobs:
         run: echo "php_versions=$(make _versions)" >> "$GITHUB_ENV"
   build:
     name: PHP
-    runs-on: ubuntu-24.04
     needs: php-versions
     if: >-
       ${{ github.event.workflow_run.conclusion == 'success' }}
     strategy:
       fail-fast: false
       matrix:
         php: ${{ fromJSON(needs.php-versions.outputs.matrix) }}
+        platform: [linux/arm64, linux/amd64]
+        include:
+          - platform: linux/arm64
+            runner: ubuntu-24.04-arm
+          - platform: linux/amd64
+            runner: ubuntu-24.04
+    runs-on: ${{ matrix.runner }}
     steps:
       - uses: actions/checkout@v6
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v3
       - name: Set up Docker Buildx
         id: buildx
         uses: docker/setup-buildx-action@v3
-      - name: Login to GitHub Container Registry
-        uses: docker/login-action@v3
-        with:
-          registry: ghcr.io
-          username: ${{ github.actor }}
-          password: ${{ github.token }}
       - name: Build PHP ${{ matrix.php }}
+        id: build
         uses: docker/build-push-action@v6
         with:
           file: "Dockerfile"
           builder: ${{ steps.buildx.outputs.name }}
-          push: true
           context: .
-          platforms: linux/amd64,linux/arm64
+          platforms: ${{ matrix.platform }}
           build-args: "php=${{ matrix.php }}"
           cache-from: type=gha
           cache-to: type=gha,mode=max
+          outputs: type=image,push-by-digest=true,name-canonical=true,push=true
           labels: |
             org.opencontainers.image.title=PHP ${{ matrix.php }}
             org.opencontainers.image.description=Docker image for PHP ${{ matrix.php }} FPM
@@ -63,6 +64,48 @@ jobs:
             org.opencontainers.image.revision=${{ github.sha }}
           tags: |
             ghcr.io/${{ github.repository }}:${{ matrix.php }}
+      - name: Export digest
+        run: |
+          mkdir -p ${{ runner.temp }}/digests
+          digest="${{ steps.build.outputs.digest }}"
+          touch "${{ runner.temp }}/digests/${digest#sha256:}"
+      - name: Upload digest
+        uses: actions/upload-artifact@v6
+        with:
+          name: digests-${{ env.PLATFORM_PAIR }}
+          path: ${{ runner.temp }}/digests/*
+          if-no-files-found: error
+          retention-days: 1
+  merge:
+    runs-on: ubuntu-24.04
+    needs:
+      - build
+    steps:
+      - name: Download digests
+        uses: actions/download-artifact@v7
+        with:
+          path: ${{ runner.temp }}/digests
+          pattern: digests-*
+          merge-multiple: true
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ github.token }}
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ghcr.io/${{ github.repository }}
+          tags: |
+            type=raw,value=${{ matrix.php }}
+      - name: Create manifest list and push
+        working-directory: ${{ runner.temp }}/digests
+        run: |
+          docker buildx imagetools create "$(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "${DOCKER_METADATA_OUTPUT_JSON}") $(printf 'ghcr.io/${{ github.repository }}@sha256:%s ' *)"
   cleanup:
     name: Cleanup
     runs-on: ubuntu-24.04