@opentelemetry/instrumentation-runtime-node

OpenTelemetry Node.js Runtime Metrics Instrumentation

This module provides automatic metric instrumentation that exposes measurements from the Performance measurement APIs (i.e. perf_hooks). It can also emit OpenTelemetry logs for uncaught exceptions. When a configured logger provider exposes forceFlush() (for example, the SDK LoggerProvider), this instrumentation calls it immediately after emitting the uncaught-exception log record as a best-effort attempt to reduce log loss on process termination.

Supported Versions

• Node.js >=14.10

Example

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({
    monitoringPrecision: 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.monitoringPrecision milliseconds after initialization). Otherwise, you may see:

# no registered metrics

Options

RuntimeNodeInstrumentation's constructor accepts the following options:

name	type	unit	default	description
monitoringPrecision	int	millisecond	10	The approximate number of milliseconds for which to calculate event loop utilization averages. A larger value will result in more accurate averages at the expense of less granular data. Should be set to below the scrape interval of your metrics collector to avoid duplicated data points.
captureUncaughtException	bool	-	false	Whether to emit a LogRecord for uncaught exceptions (severity FATAL). Uses the uncaughtExceptionMonitor process event.
applyCustomExceptionAttributes	function	-	undefined	Optional callback to attach custom attributes to emitted exception log records.

Useful links

• For more information on OpenTelemetry, visit: https://opentelemetry.io/
• For more about OpenTelemetry JavaScript: https://github.com/open-telemetry/opentelemetry-js
• For help or feedback on this project, join us in GitHub Discussions

License

Apache 2.0 - See LICENSE for more information.