Expand description
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.
use tower_http::{
add_extension::AddExtensionLayer,
compression::CompressionLayer,
propagate_header::PropagateHeaderLayer,
sensitive_headers::SetSensitiveRequestHeadersLayer,
set_header::SetResponseHeaderLayer,
trace::TraceLayer,
validate_request::ValidateRequestHeaderLayer,
};
use tower::{ServiceBuilder, service_fn, BoxError};
use http::{Request, Response, header::{HeaderName, CONTENT_TYPE, AUTHORIZATION}};
use std::{sync::Arc, net::SocketAddr, convert::Infallible, iter::once};
use bytes::Bytes;
use http_body_util::Full;
// Our request handler. This is where we would implement the application logic
// for responding to HTTP requests...
async fn handler(request: Request<Full<Bytes>>) -> Result<Response<Full<Bytes>>, BoxError> {
// ...
}
// Shared state across all request handlers --- in this case, a pool of database connections.
struct State {
pool: DatabaseConnectionPool,
}
#[tokio::main]
async fn main() {
// Construct the shared state.
let state = State {
pool: DatabaseConnectionPool::new(),
};
// Use tower's `ServiceBuilder` API to build a stack of tower middleware
// wrapping our request handler.
let service = ServiceBuilder::new()
// Mark the `Authorization` request header as sensitive so it doesn't show in logs
.layer(SetSensitiveRequestHeadersLayer::new(once(AUTHORIZATION)))
// High level logging of requests and responses
.layer(TraceLayer::new_for_http())
// Share an `Arc<State>` with all requests
.layer(AddExtensionLayer::new(Arc::new(state)))
// Compress responses
.layer(CompressionLayer::new())
// Propagate `X-Request-Id`s from requests to responses
.layer(PropagateHeaderLayer::new(HeaderName::from_static("x-request-id")))
// If the response has a known size set the `Content-Length` header
.layer(SetResponseHeaderLayer::overriding(CONTENT_TYPE, content_length_from_response))
// Authorize requests using a token
.layer(ValidateRequestHeaderLayer::bearer("passwordlol"))
// Accept only application/json, application/* and */* in a request's ACCEPT header
.layer(ValidateRequestHeaderLayer::accept("application/json"))
// Wrap a `Service` in our middleware stack
.service_fn(handler);
}
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§
- Authorization related middleware.
- Body types.
- Tools for classifying responses as either success or failure.
- Middleware which adds headers for CORS.
- Apply a transformation to the response body.
- Middleware that validates requests.
Enums§
- The latency unit used to report latencies by middleware.
Traits§
- Extension trait that adds methods to
tower::ServiceBuilder
for adding middleware from tower-http.
Type Aliases§
- Alias for a type-erased error type.