OpenTelemetry Metrics SDK

[![NPM Published Version][npm-img]][npm-url]
[![Apache License][license-image]][license-image]

This module contains the Metrics SDK of opentelemetry-js.

Used standalone, this module provides methods for manual instrumentation of code, offering full control over recording metrics for client-side JavaScript (browser) and Node.js.

It does not provide automated instrumentation of known libraries or host environment metrics out-of-the-box.

Installation

``bash
npm install --save @opentelemetry/api
npm install --save @opentelemetry/sdk-metrics
`

Usage

The basic setup of the SDK can be seen as followings:

`js
const opentelemetry = require('@opentelemetry/api');
const { MeterProvider } = require('@opentelemetry/sdk-metrics');

// To create an instrument, you first need to initialize the Meter provider.
// NOTE: The default OpenTelemetry meter provider does not record any metric instruments.
// Registering a working meter provider allows the API methods to record instruments.
opentelemetry.metrics.setGlobalMeterProvider(new MeterProvider());

// To record a metric event, we used the global singleton meter to create an instrument.
const counter = opentelemetry.metrics.getMeter('default').createCounter('foo');

// record a metric event.
counter.add(1, { attributeKey: 'attribute-value' });
`

In conditions, we may need to setup an async instrument to observe costly events:

`js
// Creating an async instrument, similar to synchronous instruments
const observableCounter = opentelemetry.metrics.getMeter('default')
.createObservableCounter('observable-counter');

// Register a single-instrument callback to the async instrument.
observableCounter.addCallback(async (observableResult) => {
// ... do async stuff
observableResult.observe(1, { attributeKey: 'attribute-value' });
});

// Register a multi-instrument callback and associate it with a set of async instruments.
opentelemetry.metrics.getMeter('default')
.addBatchObservableCallback(batchObservableCallback, [ observableCounter ]);
async function batchObservableCallback(batchObservableResult) {
// ... do async stuff
batchObservableResult.observe(observableCounter, 1, { attributeKey: 'attribute-value' });
}
`

Views can be registered when instantiating a MeterProvider:

`js
const meterProvider = new MeterProvider({
views: [
// override the bucket boundaries on my.histogram to [0, 50, 100]
{
aggregation: {
type: AggregationType.EXPLICIT_BUCKET_HISTOGRAM,
options: {
boundaries: [0, 50, 100]
}
},
instrumentName: 'my.histogram'
},
// rename 'my.counter' to 'my.renamed.counter'
{ name: 'my.renamed.counter', instrumentName: 'my.counter'}
]
})
``

Example

See examples/prometheus for an end-to-end example, including exporting metrics.

Useful links

- For more information on OpenTelemetry, visit:
- For more about OpenTelemetry JavaScript:
- For help or feedback on this project, join us in [GitHub Discussions][discussions-url]

License

Apache 2.0 - See [LICENSE][license-url] for more information.

[discussions-url]: https://github.com/open-telemetry/opentelemetry-js/discussions
[license-url]: https://github.com/open-telemetry/opentelemetry-js/blob/main/LICENSE
[license-image]: https://img.shields.io/badge/license-Apache_2.0-green.svg?style=flat
[npm-url]: https://www.npmjs.com/package/@opentelemetry/sdk-metrics
[npm-img]: https://badge.fury.io/js/%40opentelemetry%2Fsdk%2Dmetrics.svg