Build Docker images on native AMD64 and ARM64 runners

.github/workflows/publish-release-docker.yml

@@ -14,10 +14,10 @@ env:
   REGISTRY: ghcr.io
   IMAGE_NAME: ${{ github.repository }}
 
-# There is a single job in this workflow. It's configured to run on the latest available version of Ubuntu.
+# Build each architecture natively, then publish the combined image manifests.
 jobs:
   build-and-push-image:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.architecture.runner }}
     # Sets the permissions granted to the `GITHUB_TOKEN` for the actions in this job.
     permissions:
       contents: read
@@ -26,7 +26,15 @@ jobs:
       id-token: write
       #
     strategy:
+      fail-fast: false
       matrix:
+        architecture:
+          - platform: linux/amd64
+            runner: ubuntu-24.04
+            name: amd64
+          - platform: linux/arm64
+            runner: ubuntu-24.04-arm
+            name: arm64
         platform:
           - dockerfile: "Dockerfile"
             tag-suffix: ""
@@ -61,24 +69,95 @@ jobs:
             type=raw,enable=${{ github.ref_type == 'tag' }},value=${{ github.ref_name }},suffix=${{ matrix.platform.tag-suffix }}
             type=sha,suffix=${{ matrix.platform.tag-suffix }}
             type=sha,format=long,suffix=${{ matrix.platform.tag-suffix }}
-      # Register emulators so Buildx can build the ARM64 images on the AMD64 runner.
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@v4
       # This step sets up some additional capabilities to generate the provenance and sbom attestations
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v4
       # This step uses the `docker/build-push-action` action to build the image, based on your repository's `Dockerfile`. If the build succeeds, it pushes the image to GitHub Packages.
       # It uses the `context` parameter to define the build's context as the set of files located in the specified path. For more information, see "[Usage](https://github.com/docker/build-push-action#usage)" in the README of the `docker/build-push-action` repository.
-      # It uses the `tags` and `labels` parameters to tag and label the image with the output from the "meta" step.
+      # Push by digest so architecture builds do not overwrite shared image tags.
       - name: Build and push Docker image
         id: push
         uses: docker/build-push-action@v7
         with:
           file: ${{ matrix.platform.dockerfile }}
           context: .
-          platforms: linux/amd64,linux/arm64
-          push: true
-          tags: ${{ steps.meta.outputs.tags }}
+          platforms: ${{ matrix.architecture.platform }}
+          outputs: type=image,name=${{ env.REGISTRY }}/${{ env.IMAGE_NAME }},push-by-digest=true,name-canonical=true,push=true
           labels: ${{ steps.meta.outputs.labels }}
           provenance: mode=max
           sbom: true
+      - name: Export image digest
+        env:
+          DIGEST: ${{ steps.push.outputs.digest }}
+        run: |
+          mkdir -p "${RUNNER_TEMP}/digests"
+          touch "${RUNNER_TEMP}/digests/${DIGEST#sha256:}"
+      - name: Upload image digest
+        uses: actions/upload-artifact@v4
+        with:
+          name: digests-${{ matrix.platform.dockerfile }}-${{ matrix.architecture.name }}
+          path: ${{ runner.temp }}/digests/*
+          if-no-files-found: error
+          retention-days: 1
+
+  publish-manifests:
+    needs: build-and-push-image
+    runs-on: ubuntu-24.04
+    permissions:
+      contents: read
+      packages: write
+    strategy:
+      matrix:
+        platform:
+          - dockerfile: "Dockerfile"
+            tag-suffix: ""
+          - dockerfile: "Dockerfile.ios"
+            tag-suffix: "-ios"
+          - dockerfile: "Dockerfile.android"
+            tag-suffix: "-android"
+    steps:
+      - name: Download image digests
+        uses: actions/download-artifact@v4
+        with:
+          pattern: digests-${{ matrix.platform.dockerfile }}-*
+          path: ${{ runner.temp }}/digests
+          merge-multiple: true
+      - name: Log in to the Container registry
+        uses: docker/login-action@dbcb813823bdd20940b903addbd779551569679f # v4.6.0
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@v6
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          flavor: |
+            latest=false
+          tags: |
+            type=raw,value=latest,enable={{ is_default_branch }},suffix=${{ matrix.platform.tag-suffix }}
+            type=raw,enable=${{ github.event_name == 'release' || github.ref_type == 'tag' }},value=stable,suffix=${{ matrix.platform.tag-suffix }}
+            type=raw,enable=${{ github.event_name == 'release' }},value=${{ github.event.release.tag_name }},suffix=${{ matrix.platform.tag-suffix }}
+            type=raw,enable=${{ github.ref_type == 'tag' }},value=${{ github.ref_name }},suffix=${{ matrix.platform.tag-suffix }}
+            type=sha,suffix=${{ matrix.platform.tag-suffix }}
+            type=sha,format=long,suffix=${{ matrix.platform.tag-suffix }}
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v4
+      - name: Publish multi-platform image
+        working-directory: ${{ runner.temp }}/digests
+        env:
+          METADATA_JSON: ${{ steps.meta.outputs.json }}
+        run: |
+          mapfile -t tags < <(jq -r '.tags[]' <<< "$METADATA_JSON")
+          tag_args=()
+          for tag in "${tags[@]}"; do
+            tag_args+=(--tag "$tag")
+          done
+          images=()
+          for digest in *; do
+            images+=("${REGISTRY}/${IMAGE_NAME}@sha256:${digest}")
+          done
+          test "${#images[@]}" -eq 2
+          docker buildx imagetools create "${tag_args[@]}" "${images[@]}"
+          docker buildx imagetools inspect "${tags[0]}"