Crate prometheus_axum_middleware 

prometheus-axum-middleware

Middleware and utilities for integrating Prometheus metrics with Axum applications using the default Prometheus registry.

This crate is different from axum-prometheus since it uses the real prometheus implementation behind the scenes, so you can add your own metrics to the same registry using the built-in prometheus macros and APIs. It also supports the Prometheus remote write protocol, so you can push metrics to a Prometheus Pushgateway or remote write endpoint. The output is encoded using protobuf and compressed with snappy, using the prometheus_reqwest_remote_write crate. If you do not need remote write support, build the crate without default features.

Features

• Collects HTTP request metrics (counters, histograms, gauges) for method, endpoint, status, and body sizes.
• Allows dynamic prefixing of metric names for multi-service environments.
• Supports excluding specific paths from metrics collection (e.g., health checks).
• Provides a /metrics endpoint compatible with Prometheus scraping.
• Includes a pusher for sending metrics to a Prometheus Pushgateway or remote write endpoint.

MSRV

The minimum supported Rust version is 1.85.

Public API

• set_prefix - Set a prefix for all HTTP metrics (should be called before the first request).
• add_excluded_paths - Exclude paths from metrics collection (e.g., /healthcheck).
• PrometheusAxumLayer - Axum middleware to record Prometheus metrics for each HTTP request.
• render - Handler for the /metrics endpoint, returns all metrics in Prometheus text format.
• install_pusher - Periodically push metrics to a Prometheus Pushgateway or remote write endpoint when the remote-write feature is enabled, returning a Tokio task handle.

Usage

Add prometheus-axum-middleware to your Cargo.toml.

[dependencies]
prometheus-axum-middleware = "0.3.0"

Example

use axum::{routing, Router};
use prometheus_axum_middleware::{add_excluded_paths, render, set_prefix, PrometheusAxumLayer};
use std::net::SocketAddr;

#[tokio::main]
async fn main() {
    set_prefix("myservice");
    add_excluded_paths(&["/healthcheck"]);

    let app = Router::new()
        .route("/test_body_size", routing::get(async || "Hello, World!"))
        .route("/metrics", routing::get(render))
        .layer(PrometheusAxumLayer::new());

    let listener = tokio::net::TcpListener::bind(SocketAddr::from(([127, 0, 0, 1], 3000)))
        .await
        .unwrap();
    axum::serve(listener, app).await.unwrap()
}

Structs

PrometheusAxumLayer

PrometheusService

Functions

add_excluded_paths

Adds one or more paths to the list of excluded paths for metrics collection.

install_pusher

Installs a Prometheus pusher that will send metrics to the specified push gateway URL at regular intervals.

render

Gathers metrics and encodes them as Prometheus text exposition format.

set_prefix

Sets a prefix for the HTTP request metrics.