Merge pull request #144 from RafalWilinski/event-loop-optional

Event loop optional

package.json

@@ -1,6 +1,6 @@
 {
   "name": "express-status-monitor",
-  "version": "1.3.0",
+  "version": "1.3.1",
   "description": "Realtime Monitoring for Express-based Node applications",
   "main": "index.js",
   "keywords": [
@@ -59,12 +59,14 @@
   "dependencies": {
     "axios": "0.19.2",
     "debug": "4.1.1",
-    "event-loop-stats": "1.2.0",
     "handlebars": "^4.7.6",
     "on-headers": "1.0.2",
     "pidusage": "2.0.18",
     "socket.io": "2.3.0"
   },
+  "optionalDependencies": {
+    "event-loop-stats": "1.2.0"
+  },
   "scripts": {
     "test-ci": "mocha --recursive",
     "test": "mocha --recursive --watch",
@@ -80,4 +82,4 @@
     "snyk": "1.305.0"
   },
   "snyk": true
-}
+}

src/helpers/gather-os-metrics.js

@@ -1,10 +1,17 @@
 const pidusage = require('pidusage');
 const os = require('os');
 const v8 = require('v8');
-const eventLoopStats = require('event-loop-stats');
 const sendMetrics = require('./send-metrics');
 const debug = require('debug')('express-status-monitor');
 
+let eventLoopStats; // eslint-disable-line
+
+try {
+  eventLoopStats = require('event-loop-stats'); // eslint-disable-line
+} catch (error) {
+  console.warn('event-loop-stats not found, ignoring event loop metrics...');
+}
+
 module.exports = (io, span) => {
   const defaultResponse = {
     2: 0,
@@ -29,7 +36,10 @@ module.exports = (io, span) => {
     stat.load = os.loadavg();
     stat.timestamp = Date.now();
     stat.heap = v8.getHeapStatistics();
-    stat.loop = eventLoopStats.sense();
+
+    if (eventLoopStats) {
+      stat.loop = eventLoopStats.sense();
+    }
 
     span.os.push(stat);
     if (!span.responses[0] || (last.timestamp + span.interval) * 1000 < Date.now()) {