### Flow Charts ```sequence user->github: Create PR github->workflow_run: Trigger workflow workflow_run->workflow_run: Trigger workflow workflow_run->workflow_run: Build Docker image workflow_run->gcr: Push Docker image workflow_run->cloud_run: Start service cloud_run->gcr: Pull image cloud_run->pull_request_target: Return link workflow_run->github: Publish preview URL as a comment ``` ```sequence user->github: Create PR github->pull_request: Trigger workflow pull_request->http_service: Trigger external service pull_request->gcr: Ask for Docker image ready http_service->http_service:Build Docker image http_service->gcr: Push Dockerimage http_service->cloud_run: Start service cloud_run->gcr: Pull image cloud_run->http_service: Return link http_service->github: Publish preview URL as a comment ```