try using manifest

Author: danschmidt5189

.github/workflows/build.yml

@@ -13,8 +13,8 @@ jobs:
   build:
     runs-on: ${{ matrix.runner }}
     outputs:
-      build-image-arm: ${{ steps.gen-output.outputs.image-arm }}
-      build-image-x86: ${{ steps.gen-output.outputs.image-x86 }}
+      build-image-arm: ${{ steps.gen-output.outputs.image-arm64 }}
+      build-image-x64: ${{ steps.gen-output.outputs.image-x64 }}
     strategy:
       fail-fast: false
       matrix:
@@ -44,34 +44,67 @@ jobs:
         with:
           images: ${{ github.repository }}
 
-      - name: Write arch-specific image digest to outputs
-        id: gen-output
-        run: |
-          arch="${RUNNER_ARCH,,}"
-          echo $arch
-          fail
-
-      # echo "image-${{ runner.arch == 'X86' && 'x86' || 'arm' }}=${{ steps.meta.outputs.images }}@${{ steps.build.outputs.digest }}" >> "$GITHUB_OUTPUT"
       - name: Build/push the arm image
         id: build
         uses: docker/build-push-action@v6
         with:
+          # @note GHA caching needs tuning, these tend not to hit. Perhaps switch to type=registry?
           cache-from: type=gha
           cache-to: type=gha,mode=max
           labels: ${{ steps.meta.outputs.labels }}
-          platforms: local
           provenance: true
           sbom: true
           tags: ${{ steps.meta.outputs.tags }}
-          outputs: push-by-digest=true,type=image,push=true
+          outputs: type=image,push-by-digest=true,push=true
 
-  test:
+      - name: Write arch-specific image digest to outputs
+        id: gen-output
+        run: |
+          echo "image-${RUNNER_ARCH,,}=${{ steps.meta.outputs.tags }}@${{ steps.build.outputs.digest }}" | tee -a "$GITHUB_OUTPUT"
+
+  merge:
     runs-on: ubuntu-24.04
     needs:
       - build
+    outputs:
+      build-image: ${{ steps.meta.outputs.tags }}
+    env:
+      DOCKER_APP_IMAGE_ARM64: ${{ needs.build.outputs.build-image-arm }}
+      DOCKER_APP_IMAGE_X64: ${{ needs.build.outputs.build-image-x64 }}
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ github.repository }}
+          tags: |
+            type=sha,suffix=-build-${{ github.run_id }}_${{ github.run_attempt }}
+
+      - name: Push the multi-platform image
+        run: |
+          docker manifest create \
+            --amend "$DOCKER_APP_IMAGE_ARM64" \
+            --amend "$DOCKER_APP_IMAGE_X64" \
+            ${{ steps.meta.outputs.tags }}
+          docker manifest push ${{ steps.meta.outputs.tags }}
+
+  test:
+    runs-on: ubuntu-24.04
+    needs:
+      - merge
     env:
       COMPOSE_FILE: docker-compose.yml:docker-compose.ci.yml
-      DOCKER_APP_IMAGE: ${{ needs.build.outputs.build-image-x86 }}
+      DOCKER_APP_IMAGE: ${{ needs.merge.outputs.build-image }}
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
@@ -95,10 +128,10 @@ jobs:
   push:
     runs-on: ubuntu-24.04
     needs:
-      - build
+      - merge
       - test
     env:
-      DOCKER_APP_IMAGE: ${{ needs.build.outputs.build-image-x86 }}
+      DOCKER_APP_IMAGE: ${{ needs.merge.outputs.build-image }}
     steps:
       - name: Checkout code
         uses: actions/checkout@v4