How to Add Metrics to a Rust Application (prometheus, metrics crate)

Add the metrics crate to your Cargo.toml, initialize the recorder in main, and export metrics using the metrics::counter! macro.

[dependencies]
metrics = "0.24"
metrics-util = "0.19"
metrics-exporter-prometheus = "0.16"

use metrics::{counter, set_global_recorder};
use metrics_util::recorder::AggregationRecorder;
use metrics_exporter_prometheus::{PrometheusBuilder, PrometheusHandle};

fn main() {
    let recorder = AggregationRecorder::new();
    let handle = PrometheusBuilder::new()
        .install_recorder(&recorder)
        .unwrap();

    counter!("http_requests_total", "method" => "GET").increment(1);

    // Serve metrics at /metrics via handle.render() in your HTTP handler
    println!("Metrics available via handle.render()");
}

Adding metrics to a Rust application creates a dashboard that counts events like button clicks or errors. It functions as a digital odometer accessible via a web browser to verify your app's health. You use this approach when you need to monitor software performance in real time.