Push to Google Container Registry (GCR) from GitHub Actions

docker.yml

name: Docker Image CI

on:
  push:
    branches: [ master ]
  pull_request:
    branches: [ master ]

jobs:

  build:

    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v2

    - name: Build and push Docker images
      uses: docker/build-push-action@v1.1.0
      with:
        # Username used to log in to a Docker registry. If not set then no login will occur
        username: _json_key
        # Password or personal access token used to log in to a Docker registry. If not set then no login will occur
        password: ${{ secrets.GCLOUD_SERVICE_KEY }}
        # Server address of Docker registry. If not set then will default to Docker Hub
        registry: gcr.io
        # Docker repository to tag the image with
        repository: ${{ secrets.GOOGLE_PROJECT_ID }}/<DOCKER IMAGE NAME>
        # Comma-delimited list of tags. These will be added to the registry/repository to form the image's tags
        tags: latest
        # Automatically tags the built image with the git reference as per the readme
        tag_with_ref: true
        # Automatically tags the built image with the git short SHA as per the readme
        tag_with_sha: true
        # Comma-delimited list of labels to add to the built image
        labels: github-action-build
        # Whether to push the image
        push: true