[1] GitHub Actionsのワークフロー構文 - GitHub Docs (10/5/2021, 6:27:57 AM) https://docs.github.com/ja/actions/learn-github-actions/workflow-syntax-for-github-actions#example-using-status-check-functions
docker://{image}:{tag}
docker://{host}/{image}:{tag}
Google search: docker: