kora_lib/metrics/
handler.rs

1use crate::rpc_server::middleware_utils::build_response_with_graceful_error;
2use futures_util::future::BoxFuture;
3use http::{Request, Response, StatusCode};
4use jsonrpsee::server::logger::Body;
5use std::{
6    collections::HashMap,
7    task::{Context, Poll},
8};
9use tower::{Layer, Service};
10
11/// Layer that intercepts /metrics requests and returns Prometheus metrics directly
12#[derive(Clone)]
13pub struct MetricsHandlerLayer {
14    endpoint: String,
15}
16
17impl MetricsHandlerLayer {
18    pub fn new(endpoint: String) -> Self {
19        Self { endpoint }
20    }
21}
22
23impl Default for MetricsHandlerLayer {
24    fn default() -> Self {
25        Self { endpoint: "/metrics".to_string() }
26    }
27}
28
29impl<S> Layer<S> for MetricsHandlerLayer {
30    type Service = MetricsHandlerService<S>;
31
32    fn layer(&self, inner: S) -> Self::Service {
33        MetricsHandlerService { inner, endpoint: self.endpoint.clone() }
34    }
35}
36
37#[derive(Clone)]
38pub struct MetricsHandlerService<S> {
39    inner: S,
40    endpoint: String,
41}
42
43impl<S> Service<Request<Body>> for MetricsHandlerService<S>
44where
45    S: Service<Request<Body>, Response = Response<Body>> + Clone + Send + 'static,
46    S::Future: Send + 'static,
47{
48    type Response = Response<Body>;
49    type Error = S::Error;
50    type Future = BoxFuture<'static, Result<Self::Response, Self::Error>>;
51
52    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
53        self.inner.poll_ready(cx)
54    }
55
56    fn call(&mut self, req: Request<Body>) -> Self::Future {
57        // Check if this is a metrics request
58        let endpoint = self.endpoint.clone();
59        if req.uri().path() == endpoint && req.method() == http::Method::GET {
60            // Return metrics directly
61            Box::pin(async move {
62                match crate::metrics::gather() {
63                    Ok(metrics) => Ok(build_response_with_graceful_error(
64                        Some(HashMap::from([(
65                            "content-type".to_string(),
66                            "text/plain; version=0.0.4".to_string(),
67                        )])),
68                        StatusCode::OK,
69                        &metrics,
70                    )),
71                    Err(e) => Ok(build_response_with_graceful_error(
72                        None,
73                        StatusCode::INTERNAL_SERVER_ERROR,
74                        &format!("Error gathering metrics: {e}"),
75                    )),
76                }
77            })
78        } else {
79            // Pass through to inner service
80            let mut inner = self.inner.clone();
81            Box::pin(async move { inner.call(req).await })
82        }
83    }
84}
kora_lib/metrics/handler.rs

kora_lib/metrics/
handler.rs
