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import { Application, Request, Response } from 'express'
import { Meter, metrics } from '@opentelemetry/api-metrics'
import { PrometheusExporter } from '@opentelemetry/exporter-prometheus'
import { MeterProvider } from '@opentelemetry/sdk-metrics-base'
import { logger } from '@server/helpers/logger'
import { CONFIG } from '@server/initializers/config'
import { JobQueueObserversBuilder, NodeJSObserversBuilder, StatsObserversBuilder } from './metric-helpers'
class OpenTelemetryMetrics {
private static instance: OpenTelemetryMetrics
private meter: Meter
private onRequestDuration: (req: Request, res: Response) => void
private constructor () {}
init (app: Application) {
if (CONFIG.OPEN_TELEMETRY.METRICS.ENABLED !== true) return
app.use((req, res, next) => {
res.once('finish', () => {
if (!this.onRequestDuration) return
this.onRequestDuration(req as Request, res as Response)
})
next()
})
}
registerMetrics () {
if (CONFIG.OPEN_TELEMETRY.METRICS.ENABLED !== true) return
logger.info('Registering Open Telemetry metrics')
const provider = new MeterProvider()
provider.addMetricReader(new PrometheusExporter({ port: CONFIG.OPEN_TELEMETRY.METRICS.PROMETHEUS_EXPORTER.PORT }))
metrics.setGlobalMeterProvider(provider)
this.meter = metrics.getMeter('default')
this.buildRequestObserver()
const nodeJSObserversBuilder = new NodeJSObserversBuilder(this.meter, provider)
nodeJSObserversBuilder.buildObservers()
const jobQueueObserversBuilder = new JobQueueObserversBuilder(this.meter)
jobQueueObserversBuilder.buildObservers()
const statsObserversBuilder = new StatsObserversBuilder(this.meter)
statsObserversBuilder.buildObservers()
}
private buildRequestObserver () {
const requestDuration = this.meter.createHistogram('http_request_duration_ms', {
unit: 'milliseconds',
description: 'Duration of HTTP requests in ms'
})
this.onRequestDuration = (req: Request, res: Response) => {
const duration = Date.now() - res.locals.requestStart
requestDuration.record(duration, {
path: this.buildRequestPath(req.originalUrl),
method: req.method,
statusCode: res.statusCode + ''
})
}
}
private buildRequestPath (path: string) {
return path.split('?')[0]
}
static get Instance () {
return this.instance || (this.instance = new this())
}
}
export {
OpenTelemetryMetrics
}
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