How can you get the matched route in middleware? #1505

crunchwrapsupreme666 · 2022-10-28T19:43:55Z

crunchwrapsupreme666
Oct 28, 2022

I would like to emit metrics about the route, response code, and latency in a middleware function. But I'm having trouble figuring out how to get the matched path (and not the actual request path) for paths that match on wildcards. To be more specific, I have a route:

.route("/player/:name", get(routes::player::get_player))

and a middleware function:

.layer(middleware::from_fn(move |req, res| {
    record_metrics(req, res, metrics.clone())
}))

async fn record_metrics(
    req: Request<Body>,
    next: Next<Body>,
    metrics: Arc<Metrics>,
) -> Result<impl IntoResponse, (StatusCode, String)> {
    let method = req.method().clone();
    let path = req.uri().clone();
    tracing::info!("{:?}", req.uri());  <--- /player/player1 but I would like this to be the matched path, i.e. /player/:name

    let timer = metrics
        .request_latency
        .with_label_values(&[method.as_str(), &path.to_string()])
        .start_timer();

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

    tracing::debug!("{} {} {}", method, path, res.status());
    timer.observe_duration();
    metrics
        .request
        .with_label_values(&[
            method.as_str(),
            &path.to_string(),
            &res.status().to_string(),
        ])
        .inc();

    Ok(res)
}

How can I get the matched path in the middleware function? I know there is an extractor for the matched path but I'm not sure how to use that here.

Answered by jplatte

Oct 28, 2022

You don't need to use the extractor, you can get the MatchedPath from the request extensions, as shown in the second example in the documentation.

View full answer

jplatte · 2022-10-28T19:57:20Z

jplatte
Oct 28, 2022
Maintainer

You don't need to use the extractor, you can get the MatchedPath from the request extensions, as shown in the second example in the documentation.

0 replies

davidpdrsn · 2022-10-28T20:10:20Z

davidpdrsn
Oct 28, 2022
Collaborator

This should also work if you're on 0.6.0-rc.x

.layer(middleware::from_fn(move |matched_path, req, next| {
    record_metrics(matched_path, req, next, metrics.clone())
}))

async fn record_metrics(
    matched_path: MatchedPath,
    req: Request<Body>,
    next: Next<Body>,
    metrics: Arc<Metrics>,
) -> Result<impl IntoResponse, (StatusCode, String)> {
    ...
}

0 replies

crunchwrapsupreme666 · 2022-10-28T21:56:29Z

crunchwrapsupreme666
Oct 28, 2022
Author

Thanks!

0 replies

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How can you get the matched route in middleware? #1505

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How can you get the matched route in middleware? #1505

crunchwrapsupreme666 Oct 28, 2022

Replies: 3 comments

jplatte Oct 28, 2022 Maintainer

davidpdrsn Oct 28, 2022 Collaborator

crunchwrapsupreme666 Oct 28, 2022 Author

crunchwrapsupreme666
Oct 28, 2022

jplatte
Oct 28, 2022
Maintainer

davidpdrsn
Oct 28, 2022
Collaborator

crunchwrapsupreme666
Oct 28, 2022
Author