A Prometheus middleware to collect HTTP metrics for Axum applications.
axum-prometheus relies on metrics_exporter_prometheus as a backed to interact with Prometheus.
By default three HTTP metrics are tracked
axum_http_requests_total(labels: endpoint, method): the total number of HTTP requests handled (counter)axum_http_requests_duration_seconds(labels: endpoint, method, status): the request duration for all HTTP requests handled (histogram)axum_http_requests_pending(labels: endpoint, method): the number of currently in-flight requests (gauge)
Note that in the future request size metric is also planned to be implemented.
These metrics can be renamed by specifying environmental variables at compile time:
AXUM_HTTP_REQUESTS_TOTALAXUM_HTTP_REQUESTS_DURATION_SECONDSAXUM_HTTP_REQUESTS_PENDING
These environmental variables can be set in your .cargo/config.toml since Cargo 1.56:
[env]
AXUM_HTTP_REQUESTS_TOTAL = "my_app_requests_total"
AXUM_HTTP_REQUESTS_DURATION_SECONDS = "my_app_requests_duration_seconds"
AXUM_HTTP_REQUESTS_PENDING = "my_app_requests_pending"..or optionally use [PrometheusMetricLayerBuilder::with_prefix] function.
| Axum Version | Crate Version |
|---|---|
0.5 |
0.1 |
0.6 |
0.2, 0.3 |
For more elaborate use-cases, see the builder example.
Add axum-prometheus to your Cargo.toml.
[dependencies]
axum-prometheus = "0.3.1"Then you instantiate the prometheus middleware:
use std::{net::SocketAddr, time::Duration};
use axum::{routing::get, Router};
use axum_prometheus::PrometheusMetricLayer;
#[tokio::main]
async fn main() {
let (prometheus_layer, metric_handle) = PrometheusMetricLayer::pair();
let app = Router::new()
.route("/fast", get(|| async {}))
.route(
"/slow",
get(|| async {
tokio::time::sleep(Duration::from_secs(1)).await;
}),
)
.route("/metrics", get(|| async move { metric_handle.render() }))
.layer(prometheus_layer);
let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
axum::Server::bind(&addr)
.serve(app.into_make_service())
.await
.unwrap();
}Note that the /metrics endpoint is not automatically exposed, so you need to add that as a route manually.
Calling the /metrics endpoint will expose your metrics:
axum_http_requests_total{method="GET",endpoint="/metrics"} 5
axum_http_requests_pending{method="GET",endpoint="/metrics"} 1
axum_http_requests_duration_seconds_bucket{method="GET",status="200",endpoint="/metrics",le="0.005"} 4
axum_http_requests_duration_seconds_bucket{method="GET",status="200",endpoint="/metrics",le="0.01"} 4
axum_http_requests_duration_seconds_bucket{method="GET",status="200",endpoint="/metrics",le="0.025"} 4
axum_http_requests_duration_seconds_bucket{method="GET",status="200",endpoint="/metrics",le="0.05"} 4
axum_http_requests_duration_seconds_bucket{method="GET",status="200",endpoint="/metrics",le="0.1"} 4
axum_http_requests_duration_seconds_bucket{method="GET",status="200",endpoint="/metrics",le="0.25"} 4
axum_http_requests_duration_seconds_bucket{method="GET",status="200",endpoint="/metrics",le="0.5"} 4
axum_http_requests_duration_seconds_bucket{method="GET",status="200",endpoint="/metrics",le="1"} 4
axum_http_requests_duration_seconds_bucket{method="GET",status="200",endpoint="/metrics",le="2.5"} 4
axum_http_requests_duration_seconds_bucket{method="GET",status="200",endpoint="/metrics",le="5"} 4
axum_http_requests_duration_seconds_bucket{method="GET",status="200",endpoint="/metrics",le="10"} 4
axum_http_requests_duration_seconds_bucket{method="GET",status="200",endpoint="/metrics",le="+Inf"} 4
axum_http_requests_duration_seconds_sum{method="GET",status="200",endpoint="/metrics"} 0.001997171
axum_http_requests_duration_seconds_count{method="GET",status="200",endpoint="/metrics"} 4
This crate is similar to (and takes inspiration from) actix-web-pr
517A
om and rocket_prometheus,
and also builds on top of davidpdrsn's earlier work with LifeCycleHooks in tower-http.