Module tower_http::catch_panic

source ·
Available on crate feature catch-panic only.
Expand description

Convert panics into responses.

Note that using panics for error handling is not recommended. Prefer instead to use Result whenever possible.

§Example

use http::{Request, Response, header::HeaderName};
use std::convert::Infallible;
use tower::{Service, ServiceExt, ServiceBuilder, service_fn};
use tower_http::catch_panic::CatchPanicLayer;
use http_body_util::Full;
use bytes::Bytes;

async fn handle(req: Request<Full<Bytes>>) -> Result<Response<Full<Bytes>>, Infallible> {
    panic!("something went wrong...")
}

let mut svc = ServiceBuilder::new()
    // Catch panics and convert them into responses.
    .layer(CatchPanicLayer::new())
    .service_fn(handle);

// Call the service.
let request = Request::new(Full::default());

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

assert_eq!(response.status(), 500);

Using a custom panic handler:

use http::{Request, StatusCode, Response, header::{self, HeaderName}};
use std::{any::Any, convert::Infallible};
use tower::{Service, ServiceExt, ServiceBuilder, service_fn};
use tower_http::catch_panic::CatchPanicLayer;
use bytes::Bytes;
use http_body_util::Full;

async fn handle(req: Request<Full<Bytes>>) -> Result<Response<Full<Bytes>>, Infallible> {
    panic!("something went wrong...")
}

fn handle_panic(err: Box<dyn Any + Send + 'static>) -> Response<Full<Bytes>> {
    let details = if let Some(s) = err.downcast_ref::<String>() {
        s.clone()
    } else if let Some(s) = err.downcast_ref::<&str>() {
        s.to_string()
    } else {
        "Unknown panic message".to_string()
    };

    let body = serde_json::json!({
        "error": {
            "kind": "panic",
            "details": details,
        }
    });
    let body = serde_json::to_string(&body).unwrap();

    Response::builder()
        .status(StatusCode::INTERNAL_SERVER_ERROR)
        .header(header::CONTENT_TYPE, "application/json")
        .body(Full::from(body))
        .unwrap()
}

let svc = ServiceBuilder::new()
    // Use `handle_panic` to create the response.
    .layer(CatchPanicLayer::custom(handle_panic))
    .service_fn(handle);

Structs§

Traits§