OpenTelemetry Metrics SDK

OpenTelemetry metrics allow a user to collect data and export it to a metrics backend like Prometheus.

Installation

npm install --save @opentelemetry/metrics

Usage

Counter

Choose this kind of metric when the value is a quantity, the sum is of primary interest, and the event count and value distribution are not of primary interest. Counters are defined as Monotonic = true by default, meaning that positive values are expected.

const { MeterProvider } = require('@opentelemetry/metrics');

// Initialize the Meter to capture measurements in various ways.
const meter = new MeterProvider().getMeter('your-meter-name');

const counter = meter.createCounter('metric_name', {
  labelKeys: ['pid'],
  description: 'Example of a counter'
});

const labels = { pid: process.pid };

// Create a BoundInstrument associated with specified label values.
const boundCounter = counter.bind(labels);
boundCounter.add(10);

Observable

Choose this kind of metric when only last value is important without worry about aggregation

const { MeterProvider, MetricObservable } = require('@opentelemetry/metrics');

// Initialize the Meter to capture measurements in various ways.
const meter = new MeterProvider().getMeter('your-meter-name');

const observer = meter.createObserver('metric_name', {
  labelKeys: ['pid', 'core'],
  description: 'Example of a observer'
});

function getCpuUsage() {
  return Math.random();
}

const metricObservable = new MetricObservable();

observer.setCallback((observerResult) => {
  // synchronous callback
  observerResult.observe(getCpuUsage, { pid: process.pid, core: '1' });
  // asynchronous callback
  observerResult.observe(metricObservable, { pid: process.pid, core: '2' });
});

// simulate asynchronous operation
setInterval(()=> {
  metricObservable.next(getCpuUsage());
}, 2000)

See examples/prometheus for a short example.

Measure

Work in progress

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 on gitter

License

Apache 2.0 - See LICENSE for more information.