auto-reload

This example shows how you can set up a development environment for your axum service such that whenever the source code changes, the app is recompiled and restarted. It uses listenfd to be able to migrate connections from an old version of the app to a newly-compiled version.

Setup

cargo install cargo-watch systemfd

Running

systemfd --no-pid -s http::3000 -- cargo watch -x run

[package]
name = "auto-reload"
version = "0.1.0"
edition = "2021"
publish = false

[dependencies]
axum = { path = "../../axum" }
listenfd = "1.0.1"
tokio = { version = "1.0", features = ["full"] }

//! Run with
//!
//! ```not_rust
//! cargo run -p auto-reload
//! ```

use axum::{response::Html, routing::get, Router};
use listenfd::ListenFd;
use tokio::net::TcpListener;

#[tokio::main]
async fn main() {
    // build our application with a route
    let app = Router::new().route("/", get(handler));

    let mut listenfd = ListenFd::from_env();
    let listener = match listenfd.take_tcp_listener(0).unwrap() {
        // if we are given a tcp listener on listen fd 0, we use that one
        Some(listener) => {
            listener.set_nonblocking(true).unwrap();
            TcpListener::from_std(listener).unwrap()
        }
        // otherwise fall back to local listening
        None => TcpListener::bind("127.0.0.1:3000").await.unwrap(),
    };

    // run it
    println!("listening on {}", listener.local_addr().unwrap());
    axum::serve(listener, app).await.unwrap();
}

async fn handler() -> Html<&'static str> {
    Html("<h1>Hello, World!</h1>")
}