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