adding prometheus gauge

package.json

@@ -24,6 +24,7 @@
     "express-rate-limit": "^6.7.0",
     "ioredis": "^5.3.2",
     "morgan": "^1.10.0",
+    "prom-client": "^15.0.0",
     "redis": "^4.6.10",
     "response-time": "^2.3.2",
     "socket.io-redis": "^6.1.1",

src/wsConnectionManager.ts

@@ -5,6 +5,7 @@ import compression from 'compression';
 import { WebSocket, WebSocketServer } from 'ws';
 import { sleep } from './utils/utils';
 import { RedisClient } from './utils/redisClient';
+import { register, Gauge } from 'prom-client';
 
 // Set up env constants
 require('dotenv').config();
@@ -14,6 +15,11 @@ app.use(cors({ origin: '*' }));
 app.use(compression());
 app.set('trust proxy', 1);
 
+const wsConnectionsGauge = new Gauge({
+	name: 'websocket_connections',
+	help: 'Number of active WebSocket connections',
+});
+
 const server = http.createServer(app);
 const wss = new WebSocketServer({ server, path: '/ws' });
 
@@ -65,6 +71,7 @@ async function main() {
 
 	wss.on('connection', (ws: WebSocket) => {
 		console.log('Client connected');
+		wsConnectionsGauge.inc();
 
 		ws.on('message', async (msg) => {
 			let parsedMessage: any;
@@ -148,6 +155,8 @@ async function main() {
 
 		// Handle disconnection
 		ws.on('close', () => {
+			wsConnectionsGauge.dec();
+
 			// Clear any existing intervals and timeouts
 			clearInterval(pingIntervalId);
 			clearTimeout(pongTimeoutId);
@@ -162,17 +171,24 @@ async function main() {
 
 		ws.on('disconnect', () => {
 			console.log('Client disconnected');
+			wsConnectionsGauge.dec();
 		});
 
 		ws.on('error', (error) => {
 			console.error('Socket error:', error);
+			wsConnectionsGauge.dec();
 		});
 	});
 
 	server.listen(WS_PORT, () => {
 		console.log(`connection manager running on ${WS_PORT}`);
 	});
 
+	app.get('/metrics', async (req, res) => {
+		res.set('Content-Type', register.contentType);
+		res.end(await register.metrics());
+	});
+
 	server.on('error', (error) => {
 		console.error('Server error:', error);
 	});

yarn.lock

@@ -357,6 +357,11 @@
   resolved "https://registry.yarnpkg.com/@opentelemetry/api/-/api-1.3.0.tgz#27c6f776ac3c1c616651e506a89f438a0ed6a055"
   integrity sha512-YveTnGNsFFixTKJz09Oi4zYkiLT5af3WpZDu4aIUM7xX+2bHAkOJayFTVQd6zB8kkWPpbua4Ha6Ql00grdLlJQ==
 
+"@opentelemetry/api@^1.4.0":
+  version "1.7.0"
+  resolved "https://registry.yarnpkg.com/@opentelemetry/api/-/api-1.7.0.tgz#b139c81999c23e3c8d3c0a7234480e945920fc40"
+  integrity sha512-AdY5wvN0P2vXBi3b29hxZgSFvdhdxPB9+f0B6s//P9Q8nibRWeA3cHm8UmLpio9ABigkVHJ5NMPk+Mz8VCCyrw==
+
 "@opentelemetry/auto-instrumentations-node@^0.31.1":
   version "0.31.2"
   resolved "https://registry.yarnpkg.com/@opentelemetry/auto-instrumentations-node/-/auto-instrumentations-node-0.31.2.tgz#56984f2c2def73fced692c36431b9010a97f475f"
@@ -1699,6 +1704,11 @@ bindings@^1.3.0:
   dependencies:
     file-uri-to-path "1.0.0"
 
+[email protected]:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/bintrees/-/bintrees-1.0.2.tgz#49f896d6e858a4a499df85c38fb399b9aff840f8"
+  integrity sha512-VOMgTMwjAaUG580SXn3LacVgjurrbMme7ZZNYGSSV7mmtY6QQRh0Eg3pwIcntQ77DErK1L0NxkbetjcoXzVwKw==
+
 bn.js@^5.0.0, bn.js@^5.1.0, bn.js@^5.1.2, bn.js@^5.2.0, bn.js@^5.2.1:
   version "5.2.1"
   resolved "https://registry.yarnpkg.com/bn.js/-/bn.js-5.2.1.tgz#0bc527a6a0d18d0aa8d5b0538ce4a77dccfa7b70"
@@ -3373,6 +3383,14 @@ progress@^2.0.0:
   resolved "https://registry.yarnpkg.com/progress/-/progress-2.0.3.tgz#7e8cf8d8f5b8f239c1bc68beb4eb78567d572ef8"
   integrity sha512-7PiHtLll5LdnKIMw100I+8xJXR5gW2QwWYkT6iJva0bXitZKa/XMrSbdmg3r2Xnaidz9Qumd0VPaMrZlF9V9sA==
 
+prom-client@^15.0.0:
+  version "15.0.0"
+  resolved "https://registry.yarnpkg.com/prom-client/-/prom-client-15.0.0.tgz#067da874a2aa5d2e21bd5cdba9f24a8178bdab6a"
+  integrity sha512-UocpgIrKyA2TKLVZDSfm8rGkL13C19YrQBAiG3xo3aDFWcHedxRxI3z+cIcucoxpSO0h5lff5iv/SXoxyeopeA==
+  dependencies:
+    "@opentelemetry/api" "^1.4.0"
+    tdigest "^0.1.1"
+
 proxy-addr@^2.0.7, proxy-addr@~2.0.7:
   version "2.0.7"
   resolved "https://registry.yarnpkg.com/proxy-addr/-/proxy-addr-2.0.7.tgz#f19fe69ceab311eeb94b42e70e8c2070f9ba1025"
@@ -3864,6 +3882,13 @@ table@^6.0.9:
     string-width "^4.2.3"
     strip-ansi "^6.0.1"
 
+tdigest@^0.1.1:
+  version "0.1.2"
+  resolved "https://registry.yarnpkg.com/tdigest/-/tdigest-0.1.2.tgz#96c64bac4ff10746b910b0e23b515794e12faced"
+  integrity sha512-+G0LLgjjo9BZX2MfdvPfH+MKLCrxlXSYec5DaPYP1fe6Iyhf0/fSmJ0bFiZ1F8BT6cGXl2LpltQptzjXKWEkKA==
+  dependencies:
+    bintrees "1.0.2"
+
 text-encoding-utf-8@^1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/text-encoding-utf-8/-/text-encoding-utf-8-1.0.2.tgz#585b62197b0ae437e3c7b5d0af27ac1021e10d13"