Where is the config.json?

I’m a little confused about how this action’s side-effects are persisted. I expected to see a $HOME/.docker/config.json file but I’m not seeing it.

The problem I’m trying to solve is enabling experimental docker CLI features in a subsequent step after using docker/login-action. I’m trying:

DOCKER_CFG_PATH="${DOCKER_CONFIG:-$HOME/.docker}/config.json"
jq '. + {"experimental": "enabled"}' < "$DOCKER_CFG_PATH" | sponge "$DOCKER_CFG_PATH"

but $DOCKER_CFG_PATH doesn’t exist. When I try to create an empty config.json and set the experimental flag on that I lose my docker login session.

Any tips on enabling experimental docker CLI features after using this action? Thanks!

[mgalgs]

gaaah I just realized what my issue was, thanks to your comment.

I was trying to access ~/.docker/config.json from within my own custom action. So I was running in a docker container, not in the runner where docker/login-action does its work. That’s why I couldn’t see any ~/.docker/config.json being created. It was there on the runner, just not inside my container 🤦

To fix this, my docker login step is now two steps, and looks like this:

    - name: Login to DockerHub on runner
      uses: docker/login-action@v1
      with:
        username: ${{ secrets.DOCKERHUB_USERNAME }}
        password: ${{ secrets.DOCKERHUB_TOKEN }}
    - name: Login to DockerHub on workspace
      uses: docker://docker
      with:
        entrypoint: docker
        args: login --username="${{ secrets.DOCKERHUB_USERNAME }}" --password="${{ secrets.DOCKERHUB_TOKEN }}"

With that, I can build custom actions that use private image bases and interact with the registry from within my custom actions themselves.

I’ll submit a patch with a small note on the README in case it’s useful.

[crazy-max]

@mgalgs Just tested pulling a private image in a container and in another step of the job and it works for me.