---
title: "instrumentHTTP | Grafana k6 documentation"
description: "instrumentHTTP instruments the k6 HTTP module with baggage header."
---

> For a curated documentation index, see [llms.txt](/llms.txt). For the complete documentation index, see [llms-full.txt](/llms-full.txt).

# instrumentHTTP

The `instrumentHTTP` function instruments the k6 HTTP module with additional headers. It transparently replaces each of the k6 http module functions with versions that automatically attach a [baggage header](/docs/k6/latest/javascript-api/jslib/http-instrumentation-pyroscope/#about-baggage-header)(by default) to every request.

Instrumented functions include [del](/docs/k6/latest/javascript-api/k6-http/del/), [get](/docs/k6/latest/javascript-api/k6-http/get/), [head](/docs/k6/latest/javascript-api/k6-http/head/), [options](/docs/k6/latest/javascript-api/k6-http/options/), [patch](/docs/k6/latest/javascript-api/k6-http/patch/), [post](/docs/k6/latest/javascript-api/k6-http/post/), [put](/docs/k6/latest/javascript-api/k6-http/head/), and [request](/docs/k6/latest/javascript-api/k6-http/request/).

This means that, to instrument the HTTP requests, you don’t need to rewrite any code. Instead, call the module once in the init context. For details about propagation, refer to [About baggage header](/docs/k6/latest/javascript-api/jslib/http-instrumentation-pyroscope/#about-baggage-header).

## Parameters

Expand table

| Name              | Type                                        | Description                                                                                                                                                                                                                                                                        |
|-------------------|---------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `generateHeaders` | `function(method, body, params) headersMap` | A function taking the request method, body and params and returning a map of headers that will be attached. By default adding baggage header as explained in the [about baggage header](/docs/k6/latest/javascript-api/jslib/http-instrumentation-pyroscope/#about-baggage-header) |

## Example

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

JavaScript ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```javascript
import { check } from 'k6';
import pyroscope from 'https://jslib.k6.io/http-instrumentation-pyroscope/1.0.2/index.js';
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.
pyroscope.instrumentHTTP();

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('http://httpbin.org/get', {
    headers: {
      'X-Example-Header': 'instrumented/get',
    },
  });
};
```