server/lib/opentelemetry/metrics.ts

   1 import { Application, Request, Response } from 'express'
   2 import { Meter, metrics } from '@opentelemetry/api-metrics'
   3 import { PrometheusExporter } from '@opentelemetry/exporter-prometheus'
   4 import { MeterProvider } from '@opentelemetry/sdk-metrics-base'
   5 import { logger } from '@server/helpers/logger'
   6 import { CONFIG } from '@server/initializers/config'
   7 import {
   8   JobQueueObserversBuilder,
   9   LivesObserversBuilder,
  10   NodeJSObserversBuilder,
  11   StatsObserversBuilder,
  12   ViewersObserversBuilder
  13 } from './metric-helpers'
  14
  15 class OpenTelemetryMetrics {
  16
  17   private static instance: OpenTelemetryMetrics
  18
  19   private meter: Meter
  20
  21   private onRequestDuration: (req: Request, res: Response) => void
  22
  23   private constructor () {}
  24
  25   init (app: Application) {
  26     if (CONFIG.OPEN_TELEMETRY.METRICS.ENABLED !== true) return
  27
  28     app.use((req, res, next) => {
  29       res.once('finish', () => {
  30         if (!this.onRequestDuration) return
  31
  32         this.onRequestDuration(req as Request, res as Response)
  33       })
  34
  35       next()
  36     })
  37   }
  38
  39   registerMetrics () {
  40     if (CONFIG.OPEN_TELEMETRY.METRICS.ENABLED !== true) return
  41
  42     logger.info('Registering Open Telemetry metrics')
  43
  44     const provider = new MeterProvider()
  45
  46     provider.addMetricReader(new PrometheusExporter({ port: CONFIG.OPEN_TELEMETRY.METRICS.PROMETHEUS_EXPORTER.PORT }))
  47
  48     metrics.setGlobalMeterProvider(provider)
  49
  50     this.meter = metrics.getMeter('default')
  51
  52     this.buildRequestObserver()
  53
  54     const nodeJSObserversBuilder = new NodeJSObserversBuilder(this.meter, provider)
  55     nodeJSObserversBuilder.buildObservers()
  56
  57     const jobQueueObserversBuilder = new JobQueueObserversBuilder(this.meter)
  58     jobQueueObserversBuilder.buildObservers()
  59
  60     const statsObserversBuilder = new StatsObserversBuilder(this.meter)
  61     statsObserversBuilder.buildObservers()
  62
  63     const livesObserversBuilder = new LivesObserversBuilder(this.meter)
  64     livesObserversBuilder.buildObservers()
  65
  66     const viewersObserversBuilder = new ViewersObserversBuilder(this.meter)
  67     viewersObserversBuilder.buildObservers()
  68   }
  69
  70   private buildRequestObserver () {
  71     const requestDuration = this.meter.createHistogram('http_request_duration_ms', {
  72       unit: 'milliseconds',
  73       description: 'Duration of HTTP requests in ms'
  74     })
  75
  76     this.onRequestDuration = (req: Request, res: Response) => {
  77       const duration = Date.now() - res.locals.requestStart
  78
  79       requestDuration.record(duration, {
  80         path: this.buildRequestPath(req.originalUrl),
  81         method: req.method,
  82         statusCode: res.statusCode + ''
  83       })
  84     }
  85   }
  86
  87   private buildRequestPath (path: string) {
  88     return path.split('?')[0]
  89   }
  90
  91   static get Instance () {
  92     return this.instance || (this.instance = new this())
  93   }
  94 }
  95
  96 export {
  97   OpenTelemetryMetrics
  98 }