echo-rs 0.2.0

A simple HTTP echo server
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// Prometheus Metrics

// Standard Library Imports
use std::{future::ready, time::Instant};

// Third Party Imports
use axum::{
    extract::MatchedPath, http::Request, middleware::Next, response::IntoResponse, routing, Router,
};
use metrics_exporter_prometheus::{Matcher, PrometheusBuilder, PrometheusHandle};

#[tracing::instrument]
pub(crate) fn router() -> Router {
    let recorder_handle = setup_metrics_recorder();
    Router::new().route(
        "/metrics",
        routing::get(move || ready(recorder_handle.render())),
    )
}

#[tracing::instrument]
pub(crate) fn setup_metrics_recorder() -> PrometheusHandle {
    const EXPONENTIAL_SECONDS: &[f64] = &[
        0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1.0, 2.5, 5.0, 10.0,
    ];

    PrometheusBuilder::new()
        .set_buckets_for_metric(
            Matcher::Full("http_requests_duration_seconds".to_string()),
            EXPONENTIAL_SECONDS,
        )
        .unwrap()
        .install_recorder()
        .unwrap()
}

#[tracing::instrument(skip_all)]
#[allow(clippy::let_with_type_underscore)]
pub(crate) async fn track_metrics<B>(req: Request<B>, next: Next<B>) -> impl IntoResponse {
    let start = Instant::now();
    let path = if let Some(matched_path) = req.extensions().get::<MatchedPath>() {
        matched_path.as_str().to_owned()
    } else {
        req.uri().path().to_owned()
    };
    let method = req.method().clone();

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

    let latency = start.elapsed().as_secs_f64();
    let status = response.status().as_u16().to_string();

    let labels = [
        ("method", method.to_string()),
        ("path", path),
        ("status", status),
    ];

    metrics::increment_counter!("http_requests_total", &labels);
    metrics::histogram!("http_requests_duration_seconds", latency, &labels);

    response
}