---
title: "HTTP instrumentation for Tempo | Grafana k6 documentation"
description: "k6 Tempo instrumentation API"
---

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

# HTTP instrumentation for Tempo

> Note
> 
> The source code for this library can be found in the [grafana/jslib.k6.io](https://github.com/grafana/jslib.k6.io/tree/main/lib/http-instrumentation-tempo) GitHub repository.

The `http-instrumentation-tempo` module allows you to *instrument* HTTP requests so that they emit traces as the test runs. Use it to include a tracing context in HTTP requests, which can then be used by a tracing backend such as [Grafana Tempo](/docs/grafana-cloud/testing/k6/analyze-results/integration-with-grafana-cloud-traces/).

## Migration from `k6/experimental/tracing`

This jslib is a drop in replacement, so all you need to migrate to it is to replace `'k6/experimental/tracing'` import with `'https://jslib.k6.io/http-instrumentation-tempo/1.0.1/index.js'`

## About trace contexts

A *trace context* is a set of standardized HTTP headers added to a request that lets a tracing system correlate it with other requests as they navigate through a system. The trace context specifications, such as the supported [W3C Trace Context](https://www.w3.org/TR/trace-context/) and [Jaeger Trace Context](https://www.jaegertracing.io/docs/1.21/client-libraries/#propagation-format), define specific header names and an encoding format for the header values.

A trace context generally consists of, at least, a `trace_id`, a `span_id`, and a `sampled` flag. The `trace_id` is a unique identifier for the trace, the `span_id` is a unique identifier for the request, and the `sampled` flag is a boolean that indicates whether the request should be traced. For instance, the [W3C Trace Context](https://www.w3.org/TR/trace-context/) defines the `Traceparent` header, whose value contains a `trace_id`, a `span_id` and a `sampled` flag, encoded as a dash (`-`) separated list of hexadecimal values. When a trace context header is attached to an HTTP request, we refer to it as being *propagated* to the downstream service.

## API

Expand table

| Class/Function                                                                                  | Description                                                                                                                 |
|-------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------|
| [instrumentHTTP](/docs/k6/next/javascript-api/jslib/http-instrumentation-tempo/instrumenthttp/) | Instruments the k6 http module with tracing capabilities.                                                                   |
| [Client](/docs/k6/next/javascript-api/jslib/http-instrumentation-tempo/client/)                 | A configurable client that exposes instrumented HTTP operations and allows selectively instrumenting requests with tracing. |

## Example

This example demonstrates how to use the tracing API to instrument every HTTP request made in a script with tracing information.

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

```javascript
import { check } from 'k6';
import tempo from 'https://jslib.k6.io/http-instrumentation-tempo/1.0.1/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 trace context attached.
//
// The first argument is a configuration object that
// can be used to configure the tracer.
tempo.instrumentHTTP({
  // possible values: "w3c", "jaeger"
  propagator: 'w3c',
});

export default () => {
  // the instrumentHTTP call in the init context replaced
  // the http module with a version that will automatically
  // attach a trace context to every request.
  //
  // Because the instrumentHTTP call was configured with the
  // w3c trace propagator, this request will as a result have
  // a `traceparent` header attached.
  const res = http.get('http://httpbin.org/get', {
    headers: {
      'X-Example-Header': 'instrumented/get',
    },
  });
};
```