fix prometheus metric and add total users and active pad count (#7179)

* fix prometheus metric registration

* add totalUsers and activePads metric to prometheus

Author: Loki-Afro

src/node/handler/PadMessageHandler.ts

@@ -94,14 +94,25 @@ exports.socketio = () => {
 const sessioninfos:MapArrayType<any> = {};
 exports.sessioninfos = sessioninfos;
 
-stats.gauge('totalUsers', () => socketio ? socketio.engine.clientsCount : 0);
-stats.gauge('activePads', () => {
+function getTotalActiveUsers() {
+  return socketio ? socketio.engine.clientsCount : 0;
+}
+
+exports.getTotalActiveUsers = getTotalActiveUsers;
+
+function getActivePadCountFromSessionInfos() {
   const padIds = new Set();
   for (const {padId} of Object.values(sessioninfos)) {
     if (!padId) continue;
     padIds.add(padId);
   }
   return padIds.size;
+}
+exports.getActivePadCountFromSessionInfos = getActivePadCountFromSessionInfos;
+
+stats.gauge('totalUsers', () => getTotalActiveUsers());
+stats.gauge('activePads', () => {
+  return getActivePadCountFromSessionInfos();
 });
 
 /**

src/node/prometheus.ts

@@ -1,25 +1,38 @@
-import client from 'prom-client'
-const db = require('./db/DB').db
+import client from 'prom-client';
 
-const monitor = function () {
-  const collectDefaultMetrics = client.collectDefaultMetrics;
-  const Registry = client.Registry;
-  const register = new Registry();
-  collectDefaultMetrics({register});
-  const gaugeDB = new client.Gauge({
-    name: "ueberdb_stats",
-    help: "ueberdb stats",
-    labelNames: ['type'],
-  })
+const db = require('./db/DB').db;
+const PadMessageHandler = require('./handler/PadMessageHandler');
 
+const register = new client.Registry();
+const gaugeDB = new client.Gauge({
+  name: 'ueberdb_stats',
+  help: 'ueberdb stats',
+  labelNames: ['type'],
+});
+register.registerMetric(gaugeDB);
+
+const totalUsersGauge = new client.Gauge({
+  name: 'etherpad_total_users',
+  help: 'Total number of users',
+});
+register.registerMetric(totalUsersGauge);
+
+const activePadsGauge = new client.Gauge({
+  name: 'etherpad_active_pads',
+  help: 'Total number of active pads',
+});
+register.registerMetric(activePadsGauge);
+
+client.collectDefaultMetrics({register});
+
+const monitor = async function () {
   for (const [metric, value] of Object.entries(db.metrics)) {
     if (typeof value !== 'number') continue;
     gaugeDB.set({type: metric}, value);
   }
-
-
-  register.registerMetric(gaugeDB);
-  return register
+  activePadsGauge.set(PadMessageHandler.getActivePadCountFromSessionInfos());
+  totalUsersGauge.set(PadMessageHandler.getTotalActiveUsers());
+  return register;
 };
 
 export default monitor;