index.js

const express = require('express');
const app = express();
const promBundle = require("express-prom-bundle");
const morgan = require('morgan');
const port = process.env.PORT || 3000;

// Add the options to the prometheus middleware most option are for http_request_duration_seconds histogram metric
const metricsMiddleware = promBundle({
    includeMethod: true, 
    includePath: true, 
    includeStatusCode: true, 
    includeUp: true,
    promClient: {
        collectDefaultMetrics: {
        }
      }
});
// add the prometheus middleware to all routes
app.use(metricsMiddleware);
app.use(morgan('combined'));
app.get('/', (req, res) => {
  res.send('Hello World!');
});

app.listen(port, () => {
  console.log(`Server listening at http://localhost:${port}`);
});