Push identical image to all Docker registries

The current GitHub Actions workflow builds and pushes separate Docker
images for each registry. This results in the images published to each
registry having a different hash, despite having the same version tag.

This change modifies the Docker publishing job in the release workflow
so that a single step builds and publishes the same Docker image to all
Docker registries. For reproducability, the timestamp of the image is
also set to the last commit timestamp.

Signed-off-by: Mark S. Lewis <Mark.S.Lewis@outlook.com>

Author: bestbeforetoday

.github/workflows/release.yaml

@@ -39,12 +39,6 @@ jobs:
     permissions:
       contents: read
       packages: write
-    strategy:
-      fail-fast: false
-      matrix:
-        DOCKER_REGISTRY:
-          - "docker.io"
-          - "ghcr.io"
     steps:
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v3
@@ -57,28 +51,42 @@ jobs:
               max-parallelism = 1
       - name: Checkout
         uses: actions/checkout@v4
-      - name: Login to the ${{ matrix.DOCKER_REGISTRY }} Container Registry
+      - name: Login to Docker Hub
+        # If testing on a fork, login error may occur and can be ignored
+        continue-on-error: true
         uses: docker/login-action@v3
         with:
-          registry: ${{ matrix.DOCKER_REGISTRY }}
-          username: ${{ matrix.DOCKER_REGISTRY == 'docker.io' && secrets.DOCKERHUB_USERNAME || github.actor }}
-          password: ${{ matrix.DOCKER_REGISTRY == 'docker.io' && secrets.DOCKERHUB_TOKEN    || secrets.GITHUB_TOKEN }}
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
       - name: Docker meta
         id: meta
         uses: docker/metadata-action@v5
         with:
-          images: ${{ matrix.DOCKER_REGISTRY }}/${{ github.repository_owner }}/fabric-nodeenv
+          # If testing on a fork, Docker Hub publish might fail so place it last
+          images: |
+            ghcr.io/${{ github.repository_owner }}/fabric-nodeenv
+            ${{ github.repository_owner }}/fabric-nodeenv
           tags: |
             type=semver,pattern={{version}}
             type=semver,pattern={{major}}.{{minor}}
             type=semver,pattern={{major}}.{{minor}}.{{patch}}
+      - name: Get Git commit timestamps
+        run: echo "TIMESTAMP=$(git log -1 --pretty=%ct)" >> $GITHUB_ENV
       - name: Build and push image
         id: push
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           platforms: linux/amd64,linux/arm64
           file: docker/fabric-nodeenv/Dockerfile
           context: docker/fabric-nodeenv
           tags: ${{ steps.meta.outputs.tags }}
           push: ${{ github.event_name != 'pull_request' }}
           labels: ${{ steps.meta.outputs.labels }}
+        env:
+          SOURCE_DATE_EPOCH: ${{ env.TIMESTAMP }}