DocumentationGrafana k6JavaScript APIjslibhttp-instrumentation-pyroscope
Open source

HTTP instrumentation for Pyroscope

With jslib, you can instrument HTTP requests in a way that lets you tag Grafana Cloud Profiles with relevant information generated from k6 tests.

About baggage header

The baggage header is a standardized HTTP header used to propagate distributed context. The W3C specification goes into more detail on the specifics, but like many other headers, the baggage header is a list of key-value pairs.

This module, by default, adds three key-value pairs:

  1. Scenario name
  2. Name of the request (URL if not set)
  3. Value of __ENV.K6_CLOUDRUN_TEST_RUN_ID, which is set automatically in Grafana Cloud k6.


instrumentHTTPInstruments the k6 http module with baggage header.
ClientConfigurable Client that exposes instrumented HTTP operations.


This example demonstrates how to use the this library to instrument every HTTP request made in a script with the baggage header.

import { check } from 'k6';
import pyroscope from '';
import http from 'k6/http';

// instrumentHTTP will ensure that all requests made by the http module
// from this point forward will have a baggage context attached.

export default () => {
  // the instrumentHTTP call in the init context replaced
  // the http module with a version that will automatically
  // attach a baggage header to every request.
  const res = http.get('', {
    headers: {
      'X-Example-Header': 'instrumented/get',