Test before push using remote composite actions does not push loaded image

[jslusher]

I have two separate composite actions available in my Github org remotely.

Build composite action relevant code:

    - name: Log in to Docker Hub
      uses: docker/login-action@v3
      with:
        username: ${{ inputs.dockerhub-username }}
        password: ${{ inputs.dockerhub-password }}

    - name: Set Image Tag
      id: docker-meta
      uses: docker/metadata-action@v5
      with:
        images: myorg/${{ inputs.docker-image }}
        tags: |
          type=raw,value={{date 'YYYYMMDDHHmmss'}}-{{sha}},enable=${{ github.event_name == 'push' }}
          type=raw,value=PR-${{github.event.number}}-${{github.event.pull_request.head.sha}},enable=${{ github.event_name == 'pull_request' }}

    - name: Set up Docker Buildx
      uses: docker/setup-buildx-action@v3

    - name: Docker Build and Export
      uses: docker/build-push-action@v6
      with:
        context: ${{ inputs.docker-context }}
        file: ${{ inputs.docker-file }}
        load: true
        push: false
        secret-envs: pip-index-url=PIP_INDEX_URL
        tags: ${{ steps.docker-meta.outputs.tags }}

Deploy composite action relevant code

    - name: Log in to Docker Hub
      uses: docker/login-action@v3
      with:
        username: ${{ inputs.dockerhub-username }}
        password: ${{ inputs.dockerhub-password }}

    - name: Set up Docker Buildx
      uses: docker/setup-buildx-action@v3

    - name: Build and push
      uses: docker/build-push-action@v6
      with:
        context: ${{ inputs.docker-context }}
        file: ${{ inputs.docker-file }}
        push: true
        tags: ${{ inputs.docker-image }}

Calling GHA workflow using composite actions

      - name: Docker Build
        id: docker-build
        uses: myorg/workflows/docker-build@build-and-deploy-composites
        with:
          docker-image: myimage
          dockerhub-username: ${{ vars.DOCKER_HUB_USERNAME }}
          dockerhub-password: ${{ secrets.DOCKER_HUB_PASSWORD }}

      - name: TEST Docker Image Tag
        run: echo "Docker image tag is ${{ steps.docker-build.outputs.tags }}"

      - name: Docker Push
        uses: myorg/workflows/docker-push-and-cd-deploy@build-and-deploy-composites
        with:
          docker-image: ${{ steps.docker-build.outputs.tags }}
          dockerhub-username: ${{ vars.DOCKER_HUB_USERNAME }}
          dockerhub-password: ${{ secrets.DOCKER_HUB_PASSWORD }}

When I test this configuration, the Docker Push step does not use the image loaded in the Docker Build step. Is this to be expected? Is there any way to get it to use the loaded image or is this a limitation of composite actions?

[crazy-max]

This is expected.

setup-buildx-action uses a docker-container builder by default, and that has already come up before:

• driver-opts input not being passed to docker buildx create setup-buildx-action#405
• Question: How to enable the containerd image store feature? setup-buildx-action#257

Related prior reports on the build side:

• Test image with multiple tags from metadata-action #506
• Digest output is image ID, not RepoDigest #461
• Slow image loading with load: true #998

In your workflow, load: true loads the image into the local Docker store for that job, but a later docker/build-push-action step with push: true does not push that already-loaded image, it builds again.

If you want to push the loaded image, use docker push <tag>. If you want to rebuild and push, the current behavior is expected.