feat(html5-server): add prometheus default instrumentation

Adds prometheus client to collect html5 server metrics.
Only default Node.js metrics in this initial version.

Enable via configs in private.app.prometheus

bigbluebutton-html5/imports/startup/server/index.js

@@ -10,6 +10,7 @@ import Logger from './logger';
 import Redis from './redis';
 
 import setMinBrowserVersions from './minBrowserVersion';
+import MCSPrometheusAgent from './prom-metrics/index.js'
 
 let guestWaitHtml = '';
 

bigbluebutton-html5/imports/startup/server/prom-metrics/index.js

@@ -0,0 +1,29 @@
+const Agent = require('./promAgent.js');
+
+const METRICS_PREFIX = "html5_"
+
+const {
+    enabled: METRICS_ENABLED,
+    host: METRICS_HOST,
+    port: METRICS_PORT,
+    path: METRICS_PATH,
+    collectDefaultMetrics: COLLECT_DEFAULT_METRICS,
+  } = Meteor.settings.private.prometheus
+      ? Meteor.settings.private.prometheus
+      : { enabled: false };
+
+const MCSPrometheusAgent = new Agent(METRICS_HOST, METRICS_PORT, {
+  path: METRICS_PATH,
+  prefix: METRICS_PREFIX,
+  collectDefaultMetrics: COLLECT_DEFAULT_METRICS,
+});
+
+if (METRICS_ENABLED) {
+  MCSPrometheusAgent.start();
+}
+
+module.exports = {
+  METRICS_PREFIX,
+  Agent,
+  MCSPrometheusAgent,
+};

bigbluebutton-html5/imports/startup/server/prom-metrics/promAgent.js

@@ -0,0 +1,90 @@
+const {
+  register,
+  collectDefaultMetrics,
+} = require('prom-client');
+
+const HTTPServer = require('http')
+import Logger from '../logger';
+const LOG_PREFIX = '[prom-scrape-agt]';
+
+module.exports = class PrometheusScrapeAgent {
+  constructor(host, port, options) {
+    this.host = host;
+    this.port = port;
+    this.metrics = {};
+    this.started = false;
+
+    this.path = options.path || '/metrics';
+    this.collectDefaultMetrics = options.collectDefaultMetrics || false;
+    this.metricsPrefix = options.prefix || '';
+    this.collectionTimeout = options.collectionTimeout || 10000;
+  }
+
+  async collect(response) {
+    try {
+      response.writeHead(200, { 'Content-Type': register.contentType });
+      const content = await register.metrics();
+      response.end(content);
+      Logger.debug(`${LOG_PREFIX} Collected prometheus metrics:\n${content}`);
+    } catch (error) {
+      response.writeHead(500)
+      response.end(error.message);
+      Logger.error(`${LOG_PREFIX} Collecting prometheus metrics: ${error.message}`);
+    }
+  }
+
+  getMetricsHandler(request, response) {
+    switch (request.method) {
+      case 'GET':
+        if (request.url === this.path) return this.collect(response);
+        response.writeHead(404).end();
+        break;
+      default:
+        response.writeHead(501)
+        response.end();
+        break;
+    }
+  }
+
+  start(requestHandler = this.getMetricsHandler.bind(this)) {
+    if (this.collectDefaultMetrics) collectDefaultMetrics({
+      prefix: this.metricsPrefix,
+      timeout: this.collectionTimeout,
+    });
+
+    this.metricsServer = HTTPServer.createServer(requestHandler);
+    this.metricsServer.listen(this.port, this.host);
+    this.started = true;
+  };
+
+  injectMetrics(metricsDictionary) {
+    this.metrics = { ...this.metrics, ...metricsDictionary }
+  }
+
+  increment(metricName, labelsObject) {
+    if (!this.started) return;
+
+    const metric = this.metrics[metricName];
+    if (metric) {
+      metric.inc(labelsObject)
+    }
+  }
+
+  decrement(metricName, labelsObject) {
+    if (!this.started) return;
+
+    const metric = this.metrics[metricName];
+    if (metric) {
+      metric.dec(labelsObject)
+    }
+  }
+
+  set(metricName, value, labelsObject) {
+    if (!this.started) return;
+
+    const metric = this.metrics[metricName];
+    if (metric) {
+      metric.set(labelsObject, value)
+    }
+  }
+}

bigbluebutton-html5/package-lock.json

@@ -10001,6 +10001,14 @@
         "sisteransi": "^1.0.5"
       }
     },
+    "prom-client": {
+      "version": "13.2.0",
+      "resolved": "https://registry.npmjs.org/prom-client/-/prom-client-13.2.0.tgz",
+      "integrity": "sha512-wGr5mlNNdRNzEhRYXgboUU2LxHWIojxscJKmtG3R8f4/KiWqyYgXTLHs0+Ted7tG3zFT7pgHJbtomzZ1L0ARaQ==",
+      "requires": {
+        "tdigest": "^0.1.1"
+      }
+    },
     "prop-types": {
       "version": "15.7.2",
       "resolved": "https://registry.npmjs.org/prop-types/-/prop-types-15.7.2.tgz",

bigbluebutton-html5/package.json

@@ -51,6 +51,7 @@
     "node-sass": "^6.0.1",
     "postcss-nested": "^5.0.5",
     "probe-image-size": "^4.1.1",
+    "prom-client": "^13.2.0",
     "prop-types": "^15.7.2",
     "re-resizable": "^4.11.0",
     "react": "^16.14.0",

bigbluebutton-html5/private/config/settings.yml

@@ -711,3 +711,15 @@ private:
       version: 10
     - browser: YandexBrowser
       version: 19
+  # Direct Prometheus instrumentation.
+  # EXPERIMENTAL, so disabled by default.
+  prometheus:
+    enabled: false
+    # Scrape route host
+    host: localhost
+    # Scrape route port
+    port: 8080
+    # Metrics endpoint path
+    path: '/metrics'
+    # Whether default metrics for Node.js processes should be exported
+    collectDefaultMetrics: false