fn(Request) -> Future<Response>
Clone or download



Tower is a library of modular and reusable components for building robust networking clients and servers.

Build Status Gitter


Tower aims to make it as easy as possible to build robust networking clients and servers. It is protocol agnostic, but is designed around a request / response pattern. If your protocol is entirely stream based, Tower may not be a good fit.

Project Layout

Tower consists of a number of components, each of which live in their own sub crates.

  • tower-service: The foundational traits upon which Tower is built (docs)

  • tower-balance: A load balancer. Load is balanced across a number of services (docs.

  • tower-buffer: A buffering middleware. If the inner service is not ready to handle the next request, tower-buffer stores the request in an internal queue (docs).

  • tower-discover: Service discovery abstraction (docs).

  • tower-filter: Middleware that conditionally dispatch requests to the inner service based on a predicate (docs);

  • tower-in-flight-limit: Middleware limiting thee number of requests that are in-flight for the inner service (docs).

  • tower-mock: Testing utility for mocking a Service. This is useful for testing middleware implemeentations (docs);

  • tower-rate-limit: Middleware limiting the number of requests to the inner service over a period of time (docs).

  • tower-reconnect: Middleware that automatically reconnects the inner service when it becomes degraded (docs).

  • tower-router: Routes requests to one of many inner inner services based on the request (docs).

  • tower-timeout: Middleware that applies a timeout to requests (docs).

  • tower-util: Miscellaneous additional utilities for Tower (docs).

  • tower-watch: A middleware that rebinds the inner service each time a watch is notified (docs).


Currently, only tower-service, the foundational trait, has been released to crates.io. The rest of the library will be following shortly.


This project is licensed under the MIT license.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in Tower by you, shall be licensed as MIT, without any additional terms or conditions.