Support logging to multiple registries with a single execution of the Action

Currently, I need to login to three registries, which makes it very verbose to use this Action:

    - name: Login to ghcr.io
      uses: docker/login-action@v1
      with:
        registry: ghcr.io
        username: gha
        password: ${{ github.token }}
        
    - name: Login to docker.io
      uses: docker/login-action@v1
      with:
        username: ${{ secrets.DOCKER_USERNAME }}
        password: ${{ secrets.DOCKER_PASSWORD }}
        
    - name: Login to GCR
       uses: docker/login-action@v1
       with:
         registry: gcr.io
         username: _json_key
         password: ${{ secrets.GCR_JSON_KEY }}

It would be nice if providing a list of targets was supported. For instance:

    - name: Login to container registries
      uses: docker/login-action@v2
      with:
        targets:
          - 'ghcr.io|gha|${{ github.token }}'
          - 'docker.io|${{ secrets.DOCKER_USERNAME }}|${{ secrets.DOCKER_PASSWORD }}'
          - 'gcr.io|_json_key|${{ secrets.GCR_JSON_KEY }}'

[crazy-max]

@tpolekhin Thanks for your feedback, that sounds like legitimate to me so yes I think we could improve the current behavior. About design I will think about it. I also saw the composite actions ADR recently that could be beneficial for this use case.

[umarcor]

I’m closing this issue since the proposed feature is not to be implemented here.

FTR, I’m using a single plain JavaScript file as an alternative:

    - name: Login to container registries
      if: github.event_name != 'pull_request' && github.repository == 'hdl/containers'
      uses: ./utils/registry-login
      with:
        cmd: |
          echo '${{ secrets.GCR_JSON_KEY }}' | docker login gcr.io -u _json_key --password-stdin
          echo '${{ github.token }}' | docker login ghcr.io -u gha --password-stdin
          echo '${{ secrets.DOCKER_PASS }}' | docker login docker.io -u '${{ secrets.DOCKER_USER }}' --password-stdin

const { exec } = require('child_process');

function run(cmd) {
  exec(cmd, (error, stdout, stderr) => {
    if ( stdout.length != 0 ) { console.log(`${stdout}`); }
    if ( stderr.length != 0 ) { console.error(`${stderr}`); }
    if (error) {
      console.error(`exec error: ${error}`);
    }
    return error;
  });
}

// Are we in the 'post' step?
const registries = process.env.STATE_REGISTRIES;
if ( registries != undefined ) {
  for ( const item of registries.split(',') ) { run(`docker logout ${item.trim()}`); };
  return;
}

// Otherwise, this is the main step
run(process.env.INPUT_CMD);
console.log(`::save-state name=REGISTRIES::gcr.io,ghcr.io,docker.io`);

Ref: https://github.com/hdl/containers/tree/main/utils/registry-login