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'
9 class OpenTelemetryMetrics {
11 private static instance: OpenTelemetryMetrics
15 private onRequestDuration: (req: Request, res: Response) => void
17 private constructor () {}
19 init (app: Application) {
20 if (CONFIG.OPEN_TELEMETRY.METRICS.ENABLED !== true) return
22 app.use((req, res, next) => {
23 res.once('finish', () => {
24 if (!this.onRequestDuration) return
26 this.onRequestDuration(req as Request, res as Response)
34 if (CONFIG.OPEN_TELEMETRY.METRICS.ENABLED !== true) return
36 logger.info('Registering Open Telemetry metrics')
38 const provider = new MeterProvider()
40 provider.addMetricReader(new PrometheusExporter({ port: CONFIG.OPEN_TELEMETRY.METRICS.PROMETHEUS_EXPORTER.PORT }))
42 metrics.setGlobalMeterProvider(provider)
44 this.meter = metrics.getMeter('default')
46 this.buildRequestObserver()
48 const nodeJSObserversBuilder = new NodeJSObserversBuilder(this.meter, provider)
49 nodeJSObserversBuilder.buildObservers()
51 const jobQueueObserversBuilder = new JobQueueObserversBuilder(this.meter)
52 jobQueueObserversBuilder.buildObservers()
54 const statsObserversBuilder = new StatsObserversBuilder(this.meter)
55 statsObserversBuilder.buildObservers()
58 private buildRequestObserver () {
59 const requestDuration = this.meter.createHistogram('http_request_duration_ms', {
61 description: 'Duration of HTTP requests in ms'
64 this.onRequestDuration = (req: Request, res: Response) => {
65 const duration = Date.now() - res.locals.requestStart
67 requestDuration.record(duration, {
68 path: this.buildRequestPath(req.originalUrl),
70 statusCode: res.statusCode + ''
75 private buildRequestPath (path: string) {
76 return path.split('?')[0]
79 static get Instance () {
80 return this.instance || (this.instance = new this())