ci: Build Arm image

.github/workflows/build.yml

@@ -2,9 +2,17 @@ name: Build
 
 on: [push, pull_request]
 
+env:
+  IMAGE_NAME: dcard/workerd
+
 jobs:
   build:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        platform:
+          - linux/amd64
+          - linux/arm64
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -21,10 +29,7 @@ jobs:
         id: meta
         uses: docker/metadata-action@v5
         with:
-          images: dcard/workerd
-          tags: |
-            type=sha
-            type=raw,value=latest,enable={{is_default_branch}}
+          images: ${{ env.IMAGE_NAME }}
       - name: Set up Bazel cache
         uses: actions/cache@v3
         with:
@@ -37,11 +42,60 @@ jobs:
           cache-source: bazel-cache
           cache-target: /root/.cache/bazel
       - name: Build and push
+        id: build
         uses: docker/build-push-action@v5
         with:
           context: .
-          push: true
-          tags: ${{ steps.meta.outputs.tags }}
+          platforms: ${{ matrix.platform }}
           labels: ${{ steps.meta.outputs.labels }}
           cache-from: type=gha
           cache-to: type=gha,mode=max
+          outputs: type=image,name=${{ env.IMAGE_NAME }},push-by-digest=true,name-canonical=true,push=true
+      - name: Set PLATFORM_PAIR environment variable
+        run: |
+          platform=${{ matrix.platform }}
+          echo "PLATFORM_PAIR=${platform//\//-}" >> $GITHUB_ENV
+      - name: Export digest
+        run: |
+          mkdir -p /tmp/digests
+          digest="${{ steps.build.outputs.digest }}"
+          touch "/tmp/digests/${digest#sha256:}"
+
+      - name: Upload digest
+        uses: actions/upload-artifact@v4
+        with:
+          name: digests-${{ env.PLATFORM_PAIR }}
+          path: /tmp/digests/*
+          if-no-files-found: error
+          retention-days: 1
+  merge:
+    runs-on: ubuntu-latest
+    needs:
+      - build
+    steps:
+      - 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: Docker meta
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.IMAGE_NAME }}
+      - name: Login to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_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.IMAGE_NAME }}@sha256:%s ' *)
+      - name: Inspect image
+        run: |
+          docker buildx imagetools inspect ${{ env.IMAGE_NAME }}:${{ steps.meta.outputs.version }}