OpenTelemetry Long Task Instrumentation for web

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

This module provides automatic instrumentation for [Long Task API][mdn-long-task] which may be loaded using the @opentelemetry/sdk-trace-web package. It creates spans from tasks that take more than 50 milliseconds, all of the data reported via [PerformanceLongTaskTiming][mdn-performance-long-task-timing] is included as span attributes.

If total installation size is not constrained, it is recommended to use the @opentelemetry/auto-instrumentations-web bundle with @opentelemetry/sdk-trace-web for the most seamless instrumentation experience.

Compatible with OpenTelemetry JS API and SDK 1.0+.

Installation

``bash
npm install --save @opentelemetry/instrumentation-long-task
`

Usage

`js
import { ConsoleSpanExporter, SimpleSpanProcessor } from '@opentelemetry/sdk-trace-base';
import { WebTracerProvider } from '@opentelemetry/sdk-trace-web';
import { LongTaskInstrumentation } from '@opentelemetry/instrumentation-long-task';
import { registerInstrumentations } from '@opentelemetry/instrumentation';

const provider = new WebTracerProvider({
spanProcessors: [
new SimpleSpanProcessor(new ConsoleSpanExporter()),
],
});

registerInstrumentations({
tracerProvider: provider,
instrumentations: [
new LongTaskInstrumentation({
// see under for available configuration
}),
],
});
`

$3

| Options | Type | Description |
| --- | --- | --- |
| observerCallback | ObserverCallback | Callback executed on observed longtask, allowing additional attributes to be attached to the span. |

The observerCallback function is passed the created span and the longtask PerformanceEntry,
allowing the user to add custom attributes to the span with any logic.
For example, a web app with client-side routing can add contextual information on the current page,
even if the tracer was instantiated before navigation.

Usage Example:

`js
longtaskInstrumentationConfig = {
observerCallback: (span, longtaskEvent) => {
span.setAttribute('location.pathname', window.location.pathname)
}
}
``

Semantic Conventions

This package does not currently generate any attributes from semantic conventions.

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-contrib/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/instrumentation-long-task
[npm-img]: https://badge.fury.io/js/%40opentelemetry%2Finstrumentation-long-task.svg
[mdn-long-task]: https://developer.mozilla.org/en-US/docs/Web/API/Long_Tasks_API
[mdn-performance-long-task-timing]: https://developer.mozilla.org/en-US/docs/Web/API/PerformanceLongTaskTiming