feat(ci): build multi-arch images in parallel

.github/workflows/build-and-push-component.yaml

@@ -28,6 +28,12 @@ on:
 jobs:
   build-and-push:
     runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        platform:
+          - linux/amd64
+          - linux/arm64
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
@@ -52,16 +58,65 @@ jobs:
 
       - name: Build
         uses: docker/build-push-action@v5
+        id: build
         with:
           context: .
-          platforms: linux/amd64,linux/arm64
+          platforms: ${{ matrix.platform }}
           tags: ghcr.io/openclarity/${{ inputs.image_name }}:${{ inputs.image_tag }}
           file: ${{ inputs.dockerfile }}
-          push: ${{ inputs.push }}
-          outputs: "${{ env.OUTPUTS }}"
+          outputs: type=image,name=${{ inputs.image_name }},push-by-digest=true,name-canonical=true,push=${{ inputs.push }}
           cache-from: type=local,src=/tmp/.buildx-cache
           cache-to: type=local,dest=/tmp/.buildx-cache
           build-args: |
             VERSION=${{ inputs.image_tag }}
             BUILD_TIMESTAMP=${{ inputs.timestamp }}
             COMMIT_HASH=${{ github.sha }}
+
+      - name: Export digest
+        if: inputs.push
+        run: |
+          mkdir -p /tmp/digests
+          digest="${{ steps.build.outputs.digest }}"
+          touch "/tmp/digests/${digest#sha256:}"
+
+      - name: Upload digest
+        if: inputs.push
+        uses: actions/upload-artifact@v3
+        with:
+          name: digests
+          path: /tmp/digests/*
+          if-no-files-found: error
+          retention-days: 1
+
+  merge-and-push:
+    if: inputs.push
+    runs-on: ubuntu-latest
+    needs:
+      - build-and-push
+    steps:
+      - name: Download digests
+        uses: actions/download-artifact@v3
+        with:
+          name: digests
+          path: /tmp/digests
+
+      - name: Set up Docker 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: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Create manifest list and push
+        working-directory: /tmp/digests
+        run: |
+          # shellcheck disable=SC2046
+          docker buildx imagetools create --tag "${{ inputs.image_tag }}" \
+            $(printf '${{ inputs.image_name }}@sha256:%s ' *)
+
+      - name: Inspect image
+        run: |
+          docker buildx imagetools inspect ${{ inputs.image_name }}:${{ inputs.image_tag }}