Why FastAPI Dependencies Beat Middleware for Geolocation Lookups

A technical analysis argues that using FastAPI's dependency injection system is more effective than middleware for handling IP geolocation. The core problem with BaseHTTPMiddleware is that it executes before routing, meaning it runs on every request — including health checks, metrics, and docs endpoints — potentially placing costly network calls in front of Kubernetes liveness probes. In contrast, FastAPI's Depends() runs only on routes that explicitly declare it, eliminating unnecessary API calls and reducing latency risks. The dependency approach also provides typed return values via Pydantic models, per-request caching, and easy test overrides through app.dependency_overrides. The author recommends splitting geolocation and risk assessment into two composable dependencies, keeping the total implementation to roughly 120 lines while remaining Redis-cacheable and testable without mocking HTTP.