@duytbp/express-prometheus-route-metrics

Express middleware for collecting route metrics using prom-client. Exports Prometheus-compatible metrics for HTTP request durations, labeled by method, status code, and route path.

Features

• Collects request duration histograms for each route
• Exposes metrics at a configurable endpoint (default: /metrics)
• Customizable histogram buckets and metric names

Installation

npm install @duytbp/express-prometheus-route-metrics prom-client

Usage

const express = require("express");
const routeMetrics = require("@duytbp/express-prometheus-route-metrics");

const app = express();

// Add the metrics middleware before your routes
app.use(
  routeMetrics({
    // Optional configuration:
    // metricName: "http_request_duration_seconds",
    // metricsPath: "/metrics",
    // buckets: [0.05, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5],
    // unknownPathName: "[UNKNOWN]",
  }),
);

// Define your routes as usual
app.get("/hello", (req, res) => {
  res.send("Hello, world!");
});

// Start your server
app.listen(3000, () => {
  console.log("Server listening on port 3000");
});

This will expose Prometheus metrics at /metrics by default.