prom-client

import express from 'express'; import { collectDefaultMetrics, Registry, Counter } from 'prom-client'; const app = express(); const port = process.env.PORT || 3000; // Create a new registry to register custom metrics const register = new Registry(); // Collect default metrics like CPU, memory, event loop lag, etc. // These are registered to the custom 'register' instance. collectDefaultMetrics({ register: register, prefix: 'my_app_', labels: { APP_NAME: 'my_service' } }); // Create a custom counter metric const httpRequestCounter = new Counter({ name: 'my_app_http_requests_total', help: 'Total number of HTTP requests', labelNames: ['method', 'route', 'status'], registers: [register] }); // Example route to increment the counter app.get('/', (req, res) => { httpRequestCounter.inc({ method: 'GET', route: '/', status: 200 }); res.send('Hello World!'); }); // Expose metrics at the /metrics endpoint app.get('/metrics', async (req, res) => { res.set('Content-Type', register.contentType); res.end(await register.metrics()); }); app.listen(port, () => { console.log(`Server listening at http://localhost:${port}`); console.log(`Metrics available at http://localhost:${port}/metrics`); });