README.md

OpenTelemetry Long Task Instrumentation for web

This instrumentation creates spans from tasks that take more than 50 milliseconds using the Long Task API. All of the data reported via PerformanceLongTaskTiming is included as span attributes.

Compatible with OpenTelemetry JS API and SDK 1.0+.

Installation

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

Usage

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();

provider.addSpanProcessor(new SimpleSpanProcessor(new ConsoleSpanExporter()));

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

longtask Instrumentation Options

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 webapp with client-side routing can add contextual information on the current page, even if the tracer was instantiated before navigation.

Usage Example:

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

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.