Add Prometheus metrics support: integrate prom-client and expose /metrics endpoint

Author: karimzakzouk

app.js

@@ -5,7 +5,8 @@ const bodyParser = require('body-parser');
 const mongoose = require("mongoose");
 const app = express();
 const cors = require('cors')
-
+const client = require('prom-client');
+client.collectDefaultMetrics();
 
 app.use(bodyParser.json());
 app.use(express.static(path.join(__dirname, '/')));
@@ -83,5 +84,10 @@ app.listen(3000, () => {
     console.log("Server successfully running on port - " +3000);
 })
 
+app.get('/metrics', async (req, res) => {
+  res.set('Content-Type', client.register.contentType);
+  res.end(await client.register.metrics());
+});
+    
 
 module.exports = app;

package-lock.json

@@ -18,7 +18,8 @@
     "express": "^4.18.2",
     "mocha-junit-reporter": "^2.2.1",
     "mongoose": "5.13.20",
-    "nyc": "^15.1.0"
+    "nyc": "^15.1.0",
+    "prom-client": "^15.1.3"
   },
   "devDependencies": {
     "chai": "*",