Logging

Logging in Layered and Onion Architecture

API layer logs:

• request received
• correlation ID / trace ID
• authenticated user / tenant
• response status
• globally caught unhandled exception

Application layer logs:

• use case started
• important decisions or branches
• use case completed
• business failure that matters operationally

Domain layer logs:

• generally no logging
• maybe only in rare cases if your domain services are acting like transaction scripts and you really need observability
• even then, keep it minimal

Infrastructure layer logs:

• external calls failed
• DB retries / timeouts
• queue publish failures
• HTTP client failures
• adapter-specific technical details