rust-backend-axum

Axum is a modular web framework for Rust that handles routing, middleware, and extractors. Use modular router composition with Tower middleware integration, type-safe state management with Arc for shared fields, and proper extractor ordering to build scalable REST services with clean error handling.

Axum middleware uses Tower's layer system to process requests before handlers. Distinguish between route_layer for single routes and layer for all routes; use Extension-based user propagation for auth state and implement IntoResponse for centralized error handling across your API.

Create a Cloneable AppState struct and wrap expensive fields in Arc to share state safely across routes. Pass state through Axum's built-in State extractor, ensuring your AppState derives Clone and implements the patterns Axum expects for thread-safe, concurrent access.

Yes, Axum 0.7+ supports nested routes through Router composition, letting you build modular APIs by combining routers and sharing state cleanly. This approach scales to large applications while keeping route definitions organized and maintainable.

Place body-consuming extractors last in your handler signature because they can only run once per request. Order stateless extractors first—Path, Query, Header—followed by State, then Json or other body-based extractors to avoid binding errors.

Graceful shutdown in Axum involves listening for termination signals, stopping new requests, and waiting for in-flight requests to complete before exiting. Implement signal handlers that coordinate with your server's shutdown method to ensure clean resource cleanup.