A Starlette middleware guide for FastAPI and Python developers

Most web applications start clean with a handful of route handlers, each focused on a single business logic. As the app moves to production, the audit team wants every request logged, and the security team wants API key validation on all routes. As the app grows, we might introduce rate limiting, CORS for a new frontend, and a request ID for distributed tracing. If we keep adding these functionalities to every route handler, each handler will end up with duplicate infrastructure code wrapped ...