Module compression

Middleware that compresses response bodies.

Example

Example showing how to respond with the compressed contents of a file.

use bytes::{Bytes, BytesMut};
use http::{Request, Response, header::ACCEPT_ENCODING};
use http_body_util::{Full, BodyExt, StreamBody, combinators::UnsyncBoxBody};
use http_body::Frame;
use std::convert::Infallible;
use tokio::fs::{self, File};
use tokio_util::io::ReaderStream;
use tower::{Service, ServiceExt, ServiceBuilder, service_fn};
use tower_http::{compression::CompressionLayer, BoxError};
use futures_util::TryStreamExt;

type BoxBody = UnsyncBoxBody<Bytes, std::io::Error>;

async fn handle(req: Request<Full<Bytes>>) -> Result<Response<BoxBody>, Infallible> {
    // Open the file.
    let file = File::open("Cargo.toml").await.expect("file missing");
    // Convert the file into a `Stream` of `Bytes`.
    let stream = ReaderStream::new(file);
    // Convert the stream into a stream of data `Frame`s.
    let stream = stream.map_ok(Frame::data);
    // Convert the `Stream` into a `Body`.
    let body = StreamBody::new(stream);
    // Erase the type because its very hard to name in the function signature.
    let body = body.boxed_unsync();
    // Create response.
    Ok(Response::new(body))
}

let mut service = ServiceBuilder::new()
    // Compress responses based on the `Accept-Encoding` header.
    .layer(CompressionLayer::new())
    .service_fn(handle);

// Call the service.
let request = Request::builder()
    .header(ACCEPT_ENCODING, "gzip")
    .body(Full::<Bytes>::default())?;

let response = service
    .ready()
    .await?
    .call(request)
    .await?;

assert_eq!(response.headers()["content-encoding"], "gzip");

// Read the body
let bytes = response
    .into_body()
    .collect()
    .await?
    .to_bytes();

// The compressed body should be smaller 🤞
let uncompressed_len = fs::read_to_string("Cargo.toml").await?.len();
assert!(bytes.len() < uncompressed_len);

Modules

predicate

Predicates for disabling compression of responses.

Structs

Compression

Compress response bodies of the underlying service.

CompressionBody

Response body of Compression.

CompressionLayer

Compress response bodies of the underlying service.

DefaultPredicate

The default predicate used by Compression and CompressionLayer.

ResponseFuture

Response future of Compression.

Enums

CompressionLevel

Level of compression data should be compressed with.

Traits

Predicate

Predicate used to determine if a response should be compressed or not.