API Response Time (Performance): Golden ratio is under 100 milliseconds – that is the ideal response time. In reality response time might be slower. In that case response time below 1 second is still considered very good. Even time below 3 seconds is still acceptable.
Availability: Use CI/CD pipeline to implement rapid deploy a new App Engine service and switch all ingress to the new one; Cloud Functions are cloud native service which support high availability naturally.
Authentication & Authorization: Leverage Azure Active Directory OAuth v2 authentication for RESTful APIs.
Traceability: Log all incoming event messages from REBAR messaging and store in EventReceivedLog collection (GCP Firestore).
Security: HTTPS protocol, API authentication, parameter validation, service account based access between compute service and data storage.