axum/examples/tracing-aka-logging/src/main.rs

//! Run with
//!
//! ```not_rust
//! cargo run -p example-tracing-aka-logging
//! ```

use axum::{
    body::Bytes,
    http::{HeaderMap, Request},
    response::{Html, Response},
    routing::get,
    Router,
};
use std::{net::SocketAddr, time::Duration};
use tower_http::{classify::ServerErrorsFailureClass, trace::TraceLayer};
use tracing::Span;

#[tokio::main]
async fn main() {
    // Set the RUST_LOG, if it hasn't been explicitly defined
    if std::env::var_os("RUST_LOG").is_none() {
        std::env::set_var(
            "RUST_LOG",
            "example_tracing_aka_logging=debug,tower_http=debug",
        )
    }
    tracing_subscriber::fmt::init();

    // build our application with a route
    let app = Router::new()
        .route("/", get(handler))
        // `TraceLayer` is provided by tower-http so you have to add that as a dependency.
        // It provides good defaults but is also very customizable.
        //
        // See https://docs.rs/tower-http/0.1.1/tower_http/trace/index.html for more details.
        .layer(TraceLayer::new_for_http())
        // If you want to customize the behavior using closures here is how
        //
        // This is just for demonstration, you don't need to add this middleware twice
        .layer(
            TraceLayer::new_for_http()
                .on_request(|_request: &Request<_>, _span: &Span| {
                    // ...
                })
                .on_response(|_response: &Response, _latency: Duration, _span: &Span| {
                    // ...
                })
                .on_body_chunk(|_chunk: &Bytes, _latency: Duration, _span: &Span| {
                    // ..
                })
                .on_eos(
                    |_trailers: Option<&HeaderMap>, _stream_duration: Duration, _span: &Span| {
                        // ...
                    },
                )
                .on_failure(
                    |_error: ServerErrorsFailureClass, _latency: Duration, _span: &Span| {
                        // ...
                    },
                ),
        );

    // run it
    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();
}

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