Add arm64 platform to docker image

Author: ericmj

.github/workflows/main.yml

@@ -23,23 +23,25 @@ jobs:
       - run: mix deps.unlock --check-unused
 
   docker:
-    name: Docker
-    runs-on: ubuntu-24.04
+    name: Docker (${{ matrix.platform }})
+    runs-on: ${{ matrix.runner }}
     permissions:
       contents: "read"
       id-token: "write"
+    strategy:
+      matrix:
+        include:
+          - platform: linux/amd64
+            runner: ubuntu-24.04
+          - platform: linux/arm64
+            runner: ubuntu-24.04-arm
     env:
       IMAGE_NAME: "preview"
       PROJECT_ID: "hexpm-prod"
       SERVICE_ACCOUNT: ${{ secrets.GCLOUD_SERVICE_ACCOUNT }}
       WORKLOAD_IDENTITY_PROVIDER: ${{ secrets.GCLOUD_WORKFLOW_IDENTITY_POOL_PROVIDER }}
     steps:
       - uses: actions/checkout@v4
-      - name: Set short git commit SHA
-        id: vars
-        run: |
-          calculatedSha=$(git rev-parse --short ${{ github.sha }})
-          echo "COMMIT_SHORT_SHA=$calculatedSha" >> $GITHUB_ENV
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
       - name: Google auth
@@ -59,10 +61,70 @@ jobs:
           registry: gcr.io
           username: "oauth2accesstoken"
           password: "${{ steps.auth.outputs.access_token }}"
-      - name: Build and push
+      - name: Build and push by digest
+        id: build
         uses: docker/build-push-action@v6
         with:
-          tags: gcr.io/${{ env.PROJECT_ID }}/${{ env.IMAGE_NAME }}:${{ env.COMMIT_SHORT_SHA }}
-          push: ${{ github.event_name != 'pull_request' }}
-          cache-from: type=gha
-          cache-to: type=gha,mode=max
+          platforms: ${{ matrix.platform }}
+          outputs: type=image,name=gcr.io/${{ env.PROJECT_ID }}/${{ env.IMAGE_NAME }},push-by-digest=true,name-canonical=true,push=${{ github.event_name != 'pull_request' }}
+          cache-from: type=gha,scope=${{ matrix.platform }}
+          cache-to: type=gha,scope=${{ matrix.platform }},mode=max
+      - name: Export digest
+        if: ${{ github.event_name != 'pull_request' }}
+        run: |
+          mkdir -p /tmp/digests
+          digest="${{ steps.build.outputs.digest }}"
+          touch "/tmp/digests/${digest#sha256:}"
+      - name: Upload digest
+        if: ${{ github.event_name != 'pull_request' }}
+        uses: actions/upload-artifact@v4
+        with:
+          name: digests-${{ matrix.runner }}
+          path: /tmp/digests/*
+          if-no-files-found: error
+          retention-days: 1
+
+  docker-merge:
+    name: Docker Merge
+    runs-on: ubuntu-24.04
+    if: ${{ github.event_name != 'pull_request' }}
+    needs: docker
+    permissions:
+      contents: "read"
+      id-token: "write"
+    env:
+      IMAGE_NAME: "preview"
+      PROJECT_ID: "hexpm-prod"
+      SERVICE_ACCOUNT: ${{ secrets.GCLOUD_SERVICE_ACCOUNT }}
+      WORKLOAD_IDENTITY_PROVIDER: ${{ secrets.GCLOUD_WORKFLOW_IDENTITY_POOL_PROVIDER }}
+    steps:
+      - name: Set short git commit SHA
+        run: echo "COMMIT_SHORT_SHA=${GITHUB_SHA::7}" >> $GITHUB_ENV
+      - name: Download digests
+        uses: actions/download-artifact@v4
+        with:
+          path: /tmp/digests
+          pattern: digests-*
+          merge-multiple: true
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Google auth
+        id: auth
+        uses: "google-github-actions/auth@v2"
+        with:
+          token_format: "access_token"
+          project_id: ${{ env.PROJECT_ID }}
+          service_account: ${{ env.SERVICE_ACCOUNT }}
+          workload_identity_provider: ${{ env.WORKLOAD_IDENTITY_PROVIDER }}
+      - name: Docker Auth
+        uses: "docker/login-action@v3"
+        with:
+          registry: gcr.io
+          username: "oauth2accesstoken"
+          password: "${{ steps.auth.outputs.access_token }}"
+      - name: Create manifest list and push
+        working-directory: /tmp/digests
+        run: |
+          docker buildx imagetools create \
+            -t gcr.io/${{ env.PROJECT_ID }}/${{ env.IMAGE_NAME }}:${{ env.COMMIT_SHORT_SHA }} \
+            $(printf 'gcr.io/${{ env.PROJECT_ID }}/${{ env.IMAGE_NAME }}@sha256:%s ' *)