This module provides automatic metric instrumentation that exposes measurements from the Performance measurement APIs (i.e. perf_hooks). While currently it is limited to metrics, it may be modified to produce other signals in the future.

npm install --save @opentelemetry/sdk-node @opentelemetry/exporter-prometheus
npm install --save @opentelemetry/instrumentation-runtime-node

import { NodeSDK } from '@opentelemetry/sdk-node';
import { PrometheusExporter } from '@opentelemetry/exporter-prometheus';
import { RuntimeNodeInstrumentation } from '@opentelemetry/instrumentation-runtime-node';

const prometheusExporter = new PrometheusExporter({
  port: 9464,
  startServer: true
});

const sdk = new NodeSDK({
  metricReader: prometheusExporter,
  instrumentations: [new RuntimeNodeInstrumentation({
    eventLoopUtilizationMeasurementInterval: 5000,
  })],
});

sdk.start()

NodeSDK is the full OpenTelemetry SDK for Node.js that is a layer of abstraction on top of the @opentelemetry/sdk-metrics and @opentelemetry/sdk-trace-* packages. By specifying metricReader, it will initialize the metrics SDK and creates a MeterProvider. @opentelemetry/exporter-prometheus will output metrics collected by registered instrumentation on a /metrics endpoint.

Go to localhost:9464/metrics, and you should see:

# HELP nodejs_performance_event_loop_utilization Event loop utilization
# UNIT nodejs_performance_event_loop_utilization 1
# TYPE nodejs_performance_event_loop_utilization gauge
nodejs_performance_event_loop_utilization 0.010140079547955264

Metrics will only be exported after it has collected two ELU readings (at least approximately RuntimeNodeInstrumentationConfig.eventLoopUtilizationMeasurementInterval milliseconds after initialization). Otherwise, you may see:

# no registered metrics

RuntimeNodeInstrumentation's constructor accepts the following options:

v14.10.0+

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Apache 2.0 - See LICENSE for more information.