Github action to push a docker image to Google Cloud's Container Registry.

Set up the following resources manually in the Cloud Console or use a tool like Terraform.

• Enable Container Registry API
• Create Service Account with Role Storage Admin and export a new JSON key.

uses: mattes/gce-docker-push-action@v1
with:
  creds: ${{ secrets.GOOGLE_APPLICATION_CREDENTIALS }}
  src: org/local-image:build
  dst: gcr.io/my-project/my-image:${{github.run_number}}-${{github.sha}}