Crate tower_http 

async fn(HttpRequest) -> Result<HttpResponse, Error>

Overview

tower-http is a library that provides HTTP-specific middleware and utilities built on top of tower.

All middleware uses the http and http-body crates as the HTTP abstractions. That means they’re compatible with any library or framework that also uses those crates, such as hyper, tonic, and warp.

Example server

This example shows how to apply middleware from tower-http to a Service and then run that service using hyper and hyper-util.

use tower_http::{
    compression::CompressionLayer,
    trace::TraceLayer,
};
use tower::{ServiceBuilder, service_fn, BoxError};
use http::{Request, Response};
use std::net::{SocketAddr, Ipv6Addr};
use bytes::Bytes;
use http_body_util::Full;
use hyper_util::rt::{TokioIo, TokioExecutor};
use hyper_util::service::TowerToHyperService;


#[tokio::main]
async fn main() -> Result<(), BoxError> {
    let addr = SocketAddr::from((Ipv6Addr::LOCALHOST, 8000));
    let listener = tokio::net::TcpListener::bind(addr).await?;
    println!("Listening on http://{}", addr);

    loop {
        let (socket, _) = listener.accept().await?;

        tokio::spawn(async move {
            let socket = TokioIo::new(socket);

            // Build our middleware stack
            let service = ServiceBuilder::new()
                .layer(TraceLayer::new_for_http())
                .layer(CompressionLayer::new())
                .service_fn(handler);

            // Wrap it for hyper
            let hyper_service = TowerToHyperService::new(service);

            if let Err(err) = hyper_util::server::conn::auto::Builder::new(TokioExecutor::new())
                .serve_connection(socket, hyper_service)
                .await
            {
                eprintln!("failed to serve connection: {err:#}");
            }
        });
    }
}

Keep in mind that while this example uses hyper, tower-http supports any HTTP client/server implementation that uses the http and http-body crates.

Example client

tower-http middleware can also be applied to HTTP clients:

use tower_http::{
    decompression::DecompressionLayer,
    set_header::SetRequestHeaderLayer,
    trace::TraceLayer,
    classify::StatusInRangeAsFailures,
};
use tower::{ServiceBuilder, Service, ServiceExt};
use hyper_util::{rt::TokioExecutor, client::legacy::Client};
use http_body_util::Full;
use bytes::Bytes;
use http::{Request, HeaderValue, header::USER_AGENT};

#[tokio::main]
async fn main() {
let client = Client::builder(TokioExecutor::new()).build_http();
    let mut client = ServiceBuilder::new()
        // Add tracing and consider server errors and client
        // errors as failures.
        .layer(TraceLayer::new(
            StatusInRangeAsFailures::new(400..=599).into_make_classifier()
        ))
        // Set a `User-Agent` header on all requests.
        .layer(SetRequestHeaderLayer::overriding(
            USER_AGENT,
            HeaderValue::from_static("tower-http demo")
        ))
        // Decompress response bodies
        .layer(DecompressionLayer::new())
        // Wrap a `Client` in our middleware stack.
        // This is possible because `Client` implements
        // `tower::Service`.
        .service(client);

    // Make a request
    let request = Request::builder()
        .uri("http://example.com")
        .body(Full::<Bytes>::default())
        .unwrap();

    let response = client
        .ready()
        .await
        .unwrap()
        .call(request)
        .await
        .unwrap();
}

Feature Flags

All middleware are disabled by default and can be enabled using cargo features.

For example, to enable the Trace middleware, add the “trace” feature flag in your Cargo.toml:

tower-http = { version = "0.1", features = ["trace"] }

You can use "full" to enable everything:

tower-http = { version = "0.1", features = ["full"] }

Getting Help

If you’re new to tower its guides might help. In the tower-http repo we also have a number of examples showing how to put everything together. You’re also welcome to ask in the #tower Discord channel or open an issue with your question.

Modules

add_extensionadd-extension

Middleware that clones a value into each request’s extensions.

authauth

Authorization related middleware.

bodycatch-panic or decompression-br or decompression-deflate or decompression-gzip or decompression-zstd or fs or limit

Body types.

catch_paniccatch-panic

Convert panics into responses.

classify

Tools for classifying responses as either success or failure.

compressioncompression-br or compression-deflate or compression-gzip or compression-zstd

Middleware that compresses response bodies.

corscors

Middleware which adds headers for CORS.

decompressiondecompression-br or decompression-deflate or decompression-gzip or decompression-zstd

Middleware that decompresses request and response bodies.

follow_redirectfollow-redirect

Middleware for following redirections.

limitlimit

Middleware for limiting request bodies.

map_request_bodymap-request-body

Apply a transformation to the request body.

map_response_bodymap-response-body

Apply a transformation to the response body.

metricsmetrics

Middlewares for adding metrics to services.

normalize_pathnormalize-path

Middleware that normalizes paths.

on_early_dropon-early-drop

Middleware that detects when a response future or response body is dropped before completion.

propagate_headerpropagate-header

Propagate a header from the request to the response.

request_idrequest-id

Set and propagate request ids.

sensitive_headerssensitive-headers

Middlewares that mark headers as sensitive.

services

Services that return responses without wrapping other Services.

set_headerset-header

Middleware for setting headers on requests and responses.

set_statusset-status

Middleware to override status codes.

timeouttimeout

Middleware that applies a timeout to requests.

tracetrace

Middleware that adds high level tracing to a Service.

validate_requestvalidate-request

Middleware that validates requests.

Enums

CompressionLevelcompression-br or compression-deflate or compression-gzip or compression-zstd or decompression-br or decompression-deflate or decompression-gzip or decompression-zstd

Level of compression data should be compressed with.

LatencyUnit

The latency unit used to report latencies by middleware.

Traits

ServiceBuilderExtutil

Extension trait that adds methods to tower::ServiceBuilder for adding middleware from tower-http.

ServiceExtutil

Extension trait that adds methods to any Service for adding middleware from tower-http.

Type Aliases

BoxError

Alias for a type-erased error type.