How to use Docker tag in a following step ?

[Lucas-C]

Behaviour

From this README.md, steps.meta.outputs.tags is typed as a String.

However, when trying to use the Docker image built in a following step,
when a new image as been built,
steps.meta.outputs.tags value seems to be <image>:<tag>\n<image>:latest

This \n character causes calls to docker run ... ${{ steps.meta.outputs.tags }} to fail,
as the CI shell interprets the string following the newline as a command that does not exist.

Steps to reproduce this issue

1. Clone https://github.com/voyages-sncf-technologies/vboard
2. Create a new tag
3. Observe the Actions pipeline result

Expected behaviour

I tried to use ${{ steps.meta.outputs.tags[0] }} instead,
but this gets inetrpreted as an empty string (on non-tag builds at least).

Actual behaviour

Neither ${{ steps.meta.outputs.tags }} nor ${{ steps.meta.outputs.tags[0] }}
can actually be used in a docker command following usage of docker/metadata-action@v3 & docker/build-push-action@v2

Configuration

• Repository URL (if public): https://github.com/voyages-sncf-technologies/vboard
• Build URL (if public): https://github.com/voyages-sncf-technologies/vboard/runs/3883855145?check_suite_focus=true

  docker-build-push-ws:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - uses: docker/metadata-action@v3
        id: meta
        with:
          images: vboard/vboard-ws
      - uses: docker/login-action@v1
        if: startsWith(github.ref, 'refs/tags/')
        with:
          username: ${{ secrets.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_PASSWORD }}
      - uses: docker/build-push-action@v2
        with:
          context: vboard-ws
          push: ${{ startsWith(github.ref, 'refs/tags/') }}
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
      - name: Validating the image built can start without any error
        run: docker run -e SPRING_PROFILES_ACTIVE=test -e EXIT_AFTER_INIT=true ${{ steps.meta.outputs.tags }}

Logs

vboard-build-3883855145.log

[crazy-max]

@Lucas-C

This \n character causes calls to docker run ... ${{ steps.meta.outputs.tags }} to fail

You can change the tags separator with the sep-tags input.

Neither ${{ steps.meta.outputs.tags }} nor ${{ steps.meta.outputs.tags[0] }}
can actually be used in a docker command

I would suggest to use the version output instead:

      - name: Validating the image built can start without any error
        run: docker run -e SPRING_PROFILES_ACTIVE=test -e EXIT_AFTER_INIT=true vboard/vboard-ws:${{ steps.meta.outputs.version }}

See https://github.com/crazy-max/docker-fail2ban/blob/master/.github/workflows/build.yml

[Lucas-C]

Thank you for your answer @crazy-max !

I think this will perfectly solve my issue.
I cannot create a new tag right now, but I'm confident it should do the trick.

[ivoba]

@Lucas-C did you solve this?
I have the same problem and steps.meta.outputs.version seems not to be the solution here.

Ok nevermind, i just returned to tags: ${{ steps.meta.outputs.tags }} and it works now.
Must been something else.