axum/README.md

# axum

`axum` is a web application framework that focuses on ergonomics and modularity.

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More information about this crate can be found in the [crate documentation][docs].

## High level features

- Route requests to handlers with a macro free API.
- Declaratively parse requests using extractors.
- Simple and predictable error handling model.
- Generate responses with minimal boilerplate.
- Take full advantage of the [`tower`] and [`tower-http`] ecosystem of
  middleware, services, and utilities.

In particular the last point is what sets `axum` apart from other frameworks.
`axum` doesn't have its own middleware system but instead uses
[`tower::Service`]. This means `axum` gets timeouts, tracing, compression,
authorization, and more, for free. It also enables you to share middleware with
applications written using [`hyper`] or [`tonic`].

## Usage example

Note this example uses `main` which contains breaking changes. See the
[v0.2.x](https://github.com/tokio-rs/axum/tree/v0.2.x) branch for an example
using 0.2.

```rust
use axum::{
    routing::{get, post},
    http::StatusCode,
    response::IntoResponse,
    Json, Router,
};
use serde::{Deserialize, Serialize};
use std::net::SocketAddr;

#[tokio::main]
async fn main() {
    // initialize tracing
    tracing_subscriber::fmt::init();

    // build our application with a route
    let app = Router::new()
        // `GET /` goes to `root`
        .route("/", get(root))
        // `POST /users` goes to `create_user`
        .route("/users", post(create_user));

    // run our app with hyper
    // `axum::Server` is a re-export of `hyper::Server`
    let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
    tracing::debug!("listening on {}", addr);
    axum::Server::bind(&addr)
        .serve(app.into_make_service())
        .await
        .unwrap();
}

// basic handler that responds with a static string
async fn root() -> &'static str {
    "Hello, World!"
}

async fn create_user(
    // this argument tells axum to parse the request body
    // as JSON into a `CreateUser` type
    Json(payload): Json<CreateUser>,
) -> impl IntoResponse {
    // insert your application logic here
    let user = User {
        id: 1337,
        username: payload.username,
    };

    // this will be converted into a JSON response
    // with a status code of `201 Created`
    (StatusCode::CREATED, Json(user))
}

// the input to our `create_user` handler
#[derive(Deserialize)]
struct CreateUser {
    username: String,
}

// the output to our `create_user` handler
#[derive(Serialize)]
struct User {
    id: u64,
    username: String,
}
```

See the [crate documentation][docs] for way more examples.

## Performance

`axum` is a relatively thin layer on top of [`hyper`] and adds very little
overhead. So `axum`'s performance is comparable to [`hyper`]. You can find a
benchmark [here](https://github.com/programatik29/rust-web-benchmarks).

## Safety

This crate uses `#![forbid(unsafe_code)]` to ensure everything is implemented in
100% safe Rust.

## Minimum supported Rust version

axum 0.2's MSRV is 1.51. axum 0.3's (still work-in-progress) MSRV will be 1.54.

## Examples

The [examples] folder contains various examples of how to use `axum`. The
[docs] also have lots of examples

## Getting Help

In the `axum`'s repo we also have a [number of examples][examples] showing how
to put everything together. You're also welcome to ask in the [Discord
channel][chat] or open an [issue] with your question.

## Contributing

:balloon: Thanks for your help improving the project! We are so happy to have
you! We have a [contributing guide][guide] to help you get involved in the
`axum` project.

## License

This project is licensed under the [MIT license](LICENSE).

### Contribution

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

[examples]: https://github.com/tokio-rs/axum/tree/main/examples
[docs]: https://docs.rs/axum
[`tower`]: https://crates.io/crates/tower
[`hyper`]: https://crates.io/crates/hyper
[`tower-http`]: https://crates.io/crates/tower-http
[`tonic`]: https://crates.io/crates/tonic
[guide]: CONTRIBUTING.md
[chat]: https://discord.gg/tokio
[issue]: https://github.com/tokio-rs/axum/issues/new
[`tower::Service`]: https://docs.rs/tower/latest/tower/trait.Service.html