print-request-response

[package]
name = "example-print-request-response"
version = "0.1.0"
edition = "2021"
publish = false

[dependencies]
axum = { path = "../../axum" }
http-body-util = "0.1.0"
tokio = { version = "1.0", features = ["full"] }
tracing = "0.1"
tracing-subscriber = { version = "0.3", features = ["env-filter"] }

//! Run with
//!
//! ```not_rust
//! cargo run -p example-print-request-response
//! ```

use axum::{
    body::{Body, Bytes},
    extract::Request,
    http::StatusCode,
    middleware::{self, Next},
    response::{IntoResponse, Response},
    routing::post,
    Router,
};
use http_body_util::BodyExt;
use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};

#[tokio::main]
async fn main() {
    tracing_subscriber::registry()
        .with(
            tracing_subscriber::EnvFilter::try_from_default_env().unwrap_or_else(|_| {
                format!("{}=debug,tower_http=debug", env!("CARGO_CRATE_NAME")).into()
            }),
        )
        .with(tracing_subscriber::fmt::layer())
        .init();

    let app = Router::new()
        .route("/", post(|| async move { "Hello from `POST /`" }))
        .layer(middleware::from_fn(print_request_response));

    let listener = tokio::net::TcpListener::bind("127.0.0.1:3000")
        .await
        .unwrap();
    tracing::debug!("listening on {}", listener.local_addr().unwrap());
    axum::serve(listener, app).await.unwrap();
}

async fn print_request_response(
    req: Request,
    next: Next,
) -> Result<impl IntoResponse, (StatusCode, String)> {
    let (parts, body) = req.into_parts();
    let bytes = buffer_and_print("request", body).await?;
    let req = Request::from_parts(parts, Body::from(bytes));

    let res = next.run(req).await;

    let (parts, body) = res.into_parts();
    let bytes = buffer_and_print("response", body).await?;
    let res = Response::from_parts(parts, Body::from(bytes));

    Ok(res)
}

async fn buffer_and_print<B>(direction: &str, body: B) -> Result<Bytes, (StatusCode, String)>
where
    B: axum::body::HttpBody<Data = Bytes>,
    B::Error: std::fmt::Display,
{
    let bytes = match body.collect().await {
        Ok(collected) => collected.to_bytes(),
        Err(err) => {
            return Err((
                StatusCode::BAD_REQUEST,
                format!("failed to read {direction} body: {err}"),
            ));
        }
    };

    if let Ok(body) = std::str::from_utf8(&bytes) {
        tracing::debug!("{direction} body = {body:?}");
    }

    Ok(bytes)
}