Use github's native arm64 runners for docker builds (#33788)

.github/workflows/build-container-image.yml

@@ -1,14 +1,9 @@
 on:
   workflow_call:
     inputs:
-      platforms:
-        required: true
-        type: string
       cache:
         type: boolean
         default: true
-      use_native_arm64_builder:
-        type: boolean
       push_to_images:
         type: string
       version_prerelease:
@@ -24,42 +19,36 @@ on:
       file_to_build:
         type: string
 
+# This builds multiple images with one runner each, allowing us to build for multiple architectures
+# using Github's runners.
+# The two-step process is adapted form:
+# https://docs.docker.com/build/ci/github-actions/multi-platform/#distribute-build-across-multiple-runners
 jobs:
+  # Build each (amd64 and arm64) image separately
   build-image:
-    runs-on: ubuntu-latest
+    runs-on: ${{ startsWith(matrix.platform, 'linux/arm') && 'ubuntu-24.04-arm' || 'ubuntu-24.04' }}
+    strategy:
+      fail-fast: false
+      matrix:
+        platform:
+          - linux/amd64
+          - linux/arm64
 
     steps:
       - uses: actions/checkout@v4
 
-      - uses: docker/setup-qemu-action@v3
+      - name: Prepare
-        if: contains(inputs.platforms, 'linux/arm64') && !inputs.use_native_arm64_builder
+        env:
+          PUSH_TO_IMAGES: ${{ inputs.push_to_images }}
+        run: |
+          platform=${{ matrix.platform }}
+          echo "PLATFORM_PAIR=${platform//\//-}" >> $GITHUB_ENV
+          # Transform multi-line variable into comma-separated variable
+          image_names=${PUSH_TO_IMAGES//$'\n'/,}
+          echo "IMAGE_NAMES=${image_names%,}" >> $GITHUB_ENV
 
       - uses: docker/setup-buildx-action@v3
         id: buildx
-        if: ${{ !(inputs.use_native_arm64_builder && contains(inputs.platforms, 'linux/arm64')) }}
-
-      - name: Start a local Docker Builder
-        if: inputs.use_native_arm64_builder && contains(inputs.platforms, 'linux/arm64')
-        run: |
-          docker run --rm -d --name buildkitd -p 1234:1234 --privileged moby/buildkit:latest --addr tcp://0.0.0.0:1234
-
-      - uses: docker/setup-buildx-action@v3
-        id: buildx-native
-        if: inputs.use_native_arm64_builder && contains(inputs.platforms, 'linux/arm64')
-        with:
-          driver: remote
-          endpoint: tcp://localhost:1234
-          platforms: linux/amd64
-          append: |
-            - endpoint: tcp://${{ vars.DOCKER_BUILDER_HETZNER_ARM64_01_HOST }}:13865
-              platforms: linux/arm64
-              name: mastodon-docker-builder-arm64-01
-              driver-opts:
-                - servername=mastodon-docker-builder-arm64-01
-        env:
-          BUILDER_NODE_1_AUTH_TLS_CACERT: ${{ secrets.DOCKER_BUILDER_HETZNER_ARM64_01_CACERT }}
-          BUILDER_NODE_1_AUTH_TLS_CERT: ${{ secrets.DOCKER_BUILDER_HETZNER_ARM64_01_CERT }}
-          BUILDER_NODE_1_AUTH_TLS_KEY: ${{ secrets.DOCKER_BUILDER_HETZNER_ARM64_01_KEY }}
 
       - name: Log in to Docker Hub
         if: contains(inputs.push_to_images, 'tootsuite')
@@ -76,16 +65,18 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
-      - uses: docker/metadata-action@v5
+      - name: Docker meta
         id: meta
+        uses: docker/metadata-action@v5
         if: ${{ inputs.push_to_images != '' }}
         with:
           images: ${{ inputs.push_to_images }}
           flavor: ${{ inputs.flavor }}
-          tags: ${{ inputs.tags }}
           labels: ${{ inputs.labels }}
 
-      - uses: docker/build-push-action@v6
+      - name: Build and push by digest
+        id: build
+        uses: docker/build-push-action@v6
         with:
           context: .
           file: ${{ inputs.file_to_build }}
@@ -93,11 +84,87 @@ jobs:
             MASTODON_VERSION_PRERELEASE=${{ inputs.version_prerelease }}
             MASTODON_VERSION_METADATA=${{ inputs.version_metadata }}
             SOURCE_COMMIT=${{ github.sha }}
-          platforms: ${{ inputs.platforms }}
+          platforms: ${{ matrix.platform }}
           provenance: false
-          builder: ${{ steps.buildx.outputs.name || steps.buildx-native.outputs.name }}
           push: ${{ inputs.push_to_images != '' }}
-          tags: ${{ steps.meta.outputs.tags }}
-          labels: ${{ steps.meta.outputs.labels }}
           cache-from: ${{ inputs.cache && 'type=gha' || '' }}
           cache-to: ${{ inputs.cache && 'type=gha,mode=max' || '' }}
+          outputs: type=image,"name=${{ env.IMAGE_NAMES }}",push-by-digest=true,name-canonical=true,push=${{ inputs.push_to_images != '' }}
+
+      - name: Export digest
+        if: ${{ inputs.push_to_images != '' }}
+        run: |
+          mkdir -p "${{ runner.temp }}/digests"
+          digest="${{ steps.build.outputs.digest }}"
+          touch "${{ runner.temp }}/digests/${digest#sha256:}"
+
+      - name: Upload digest
+        if: ${{ inputs.push_to_images != '' }}
+        uses: actions/upload-artifact@v4
+        with:
+          # `hashFiles` is used to disambiguate between streaming and non-streaming images
+          name: digests-${{ hashFiles(inputs.file_to_build) }}-${{ env.PLATFORM_PAIR }}
+          path: ${{ runner.temp }}/digests/*
+          if-no-files-found: error
+          retention-days: 1
+
+  # Then merge the docker images into a single one
+  merge-images:
+    if: ${{ inputs.push_to_images != '' }}
+    runs-on: ubuntu-24.04
+    needs:
+      - build-image
+
+    env:
+      PUSH_TO_IMAGES: ${{ inputs.push_to_images }}
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Download digests
+        uses: actions/download-artifact@v4
+        with:
+          path: ${{ runner.temp }}/digests
+          # `hashFiles` is used to disambiguate between streaming and non-streaming images
+          pattern: digests-${{ hashFiles(inputs.file_to_build) }}-*
+          merge-multiple: true
+
+      - name: Log in to Docker Hub
+        if: contains(inputs.push_to_images, 'tootsuite')
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Log in to the GitHub Container registry
+        if: contains(inputs.push_to_images, 'ghcr.io')
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v5
+        if: ${{ inputs.push_to_images != '' }}
+        with:
+          images: ${{ inputs.push_to_images }}
+          flavor: ${{ inputs.flavor }}
+          tags: ${{ inputs.tags }}
+          labels: ${{ inputs.labels }}
+
+      - name: Create manifest list and push
+        working-directory: ${{ runner.temp }}/digests
+        run: |
+          echo "$PUSH_TO_IMAGES" | xargs -I{} \
+            docker buildx imagetools create $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
+              $(printf '{}@sha256:%s ' *)
+
+      - name: Inspect image
+        run: |
+          echo "$PUSH_TO_IMAGES" | xargs -i{} \
+            docker buildx imagetools inspect {}:${{ steps.meta.outputs.version }}

.github/workflows/build-nightly.yml

@@ -26,8 +26,6 @@ jobs:
     uses: ./.github/workflows/build-container-image.yml
     with:
       file_to_build: Dockerfile
-      platforms: linux/amd64,linux/arm64
-      use_native_arm64_builder: true
       cache: false
       push_to_images: |
         tootsuite/mastodon
@@ -48,8 +46,6 @@ jobs:
     uses: ./.github/workflows/build-container-image.yml
     with:
       file_to_build: streaming/Dockerfile
-      platforms: linux/amd64,linux/arm64
-      use_native_arm64_builder: true
       cache: false
       push_to_images: |
         tootsuite/mastodon-streaming

.github/workflows/build-push-pr.yml

@@ -32,8 +32,6 @@ jobs:
     uses: ./.github/workflows/build-container-image.yml
     with:
       file_to_build: Dockerfile
-      platforms: linux/amd64,linux/arm64
-      use_native_arm64_builder: true
       push_to_images: |
         ghcr.io/mastodon/mastodon
       version_metadata: ${{ needs.compute-suffix.outputs.metadata }}
@@ -49,8 +47,6 @@ jobs:
     uses: ./.github/workflows/build-container-image.yml
     with:
       file_to_build: streaming/Dockerfile
-      platforms: linux/amd64,linux/arm64
-      use_native_arm64_builder: true
       push_to_images: |
         ghcr.io/mastodon/mastodon-streaming
       version_metadata: ${{ needs.compute-suffix.outputs.metadata }}

.github/workflows/build-releases.yml

@@ -13,8 +13,6 @@ jobs:
     uses: ./.github/workflows/build-container-image.yml
     with:
       file_to_build: Dockerfile
-      platforms: linux/amd64,linux/arm64
-      use_native_arm64_builder: true
       push_to_images: |
         tootsuite/mastodon
         ghcr.io/mastodon/mastodon
@@ -34,8 +32,6 @@ jobs:
     uses: ./.github/workflows/build-container-image.yml
     with:
       file_to_build: streaming/Dockerfile
-      platforms: linux/amd64,linux/arm64
-      use_native_arm64_builder: true
       push_to_images: |
         tootsuite/mastodon-streaming
         ghcr.io/mastodon/mastodon-streaming

.github/workflows/build-security.yml

@@ -24,8 +24,6 @@ jobs:
     uses: ./.github/workflows/build-container-image.yml
     with:
       file_to_build: Dockerfile
-      platforms: linux/amd64,linux/arm64
-      use_native_arm64_builder: true
       cache: false
       push_to_images: |
         tootsuite/mastodon
@@ -46,8 +44,6 @@ jobs:
     uses: ./.github/workflows/build-container-image.yml
     with:
       file_to_build: streaming/Dockerfile
-      platforms: linux/amd64,linux/arm64
-      use_native_arm64_builder: true
       cache: false
       push_to_images: |
         tootsuite/mastodon-streaming

.github/workflows/test-image-build.yml

@@ -20,7 +20,6 @@ jobs:
     uses: ./.github/workflows/build-container-image.yml
     with:
       file_to_build: Dockerfile
-      platforms: linux/amd64 # Testing only on native platform so it is performant
       cache: true
 
   build-image-streaming:
@@ -31,5 +30,4 @@ jobs:
     uses: ./.github/workflows/build-container-image.yml
     with:
       file_to_build: streaming/Dockerfile
-      platforms: linux/amd64 # Testing only on native platform so it is performant
       cache: true