Native arm build

.github/workflows/publish_docker.yml

@@ -1,4 +1,5 @@
-name: Publish tutorial docker image
+# Recipe based on: https://docs.docker.com/build/ci/github-actions/multi-platform/#distribute-build-across-multiple-runners
+name: Build and publish platform dependent docker image
 on:
   push:
     branches:
@@ -15,8 +16,12 @@ env:
   IMAGE_NAME: ${{ github.repository }}
 
 jobs:
-  build-and-push-image:
-    runs-on: ubuntu-latest
+  build:
+    strategy:
+      matrix:
+        os: ["ubuntu-24.04", "ubuntu-24.04-arm"]
+    runs-on: ${{ matrix.os }}
+
     permissions:
       contents: read
       packages: write
@@ -25,43 +30,88 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
 
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@v3
-
-      - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
-
       - name: Log in to the Container registry
         uses: docker/login-action@v3
         with:
           registry: ${{ env.REGISTRY }}
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
       - name: Extract metadata (tags, labels) for Docker
         id: meta
         uses: docker/metadata-action@v5
         with:
           images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
 
-      - name: Build Docker image
+      - name: Set architecture tag (amd64)
+        if: ${{ matrix.os == 'ubuntu-24.04' }}
+        run: echo "ARCH_TAG=amd64" >> $GITHUB_ENV
+
+      - name: Set architecture tag (arm)
+        if: ${{ contains(matrix.os, 'arm') }}
+        run: echo "ARCH_TAG=arm64" >> $GITHUB_ENV
+
+      - name: Build and push by digest
+        id: build
         uses: docker/build-push-action@v6
         with:
-          context: .
-          load: true
-          push: false
           file: docker/Dockerfile
-          platforms: linux/amd64
-          tags: ${{ steps.meta.outputs.tags }}
+          platforms: ${{ env.ARCH_TAG }}
           labels: ${{ steps.meta.outputs.labels }}
+          outputs: type=image,"name=${{ env.REGISTRY }}/${{ env.IMAGE_NAME}}",push-by-digest=true,name-canonical=true,push=true
 
-      - name: Build (arm) and push (amd/arm) Docker image
-        uses: docker/build-push-action@v6
+      - name: Export digest
+        run: |
+          mkdir -p ${{ runner.temp }}/digests
+          digest="${{ steps.build.outputs.digest }}"
+          touch "${{ runner.temp }}/digests/${digest#sha256:}"          
+
+      - name: Upload digest
         if: github.event_name == 'push'
+        uses: actions/upload-artifact@v4
         with:
-          context: .
-          push: true
-          file: docker/Dockerfile
-          platforms: linux/amd64,linux/arm64
-          tags: ${{ steps.meta.outputs.tags }}
-          labels: ${{ steps.meta.outputs.labels }}
+          name: digests-${{ env.ARCH_TAG }}
+          path: ${{ runner.temp }}/digests/*
+          if-no-files-found: error
+          retention-days: 1
+
+  merge-and-publish:
+    if: github.event_name == 'push'
+    runs-on: ubuntu-latest
+    needs:
+      - build
+    steps:
+      - name: Download digests
+        uses: actions/download-artifact@v4
+        with:
+          path: ${{ runner.temp }}/digests
+          pattern: digests-*
+          merge-multiple: true
+
+      - name: Log in to the Container registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+
+
+      - name: Create manifest list and push
+        working-directory: ${{ runner.temp }}/digests
+        run: |
+          docker buildx imagetools create $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
+            $(printf '${{ env.REGISTRY }}/${{ env.IMAGE_NAME}}@sha256:%s ' *)          
+
+      - name: Inspect image
+        run: |
+          docker buildx imagetools inspect ${{ env.REGISTRY }}/${{ env.IMAGE_NAME}}:${{ steps.meta.outputs.version }}  
+