---
title: "Execution context variables | Grafana k6 documentation"
description: "k6/execution module provides the capability to get information about the current test execution state inside the test script"
---

# Execution context variables

In some cases, it’s really useful to have information about the script’s current test-execution state. For example, you might want to

- Have different VUs run different test logic
- Use different data for each VU and iteration
- Figure out the stage that a test is in

To solve these issues, you can use *execution context variables*.

## k6/execution

The [k6/execution](/docs/k6/latest/javascript-api/k6-execution/) module exposes details about the current execution state, such as *the name of the currently executed scenario*, *how many VUs are currently active*, and more. The module provides test-execution information via three properties:

Expand table

| Property                                                          | Meta-information and execution details about |
|-------------------------------------------------------------------|----------------------------------------------|
| [instance](/docs/k6/latest/javascript-api/k6-execution/#instance) | The current running k6 instance              |
| [scenario](/docs/k6/latest/javascript-api/k6-execution/#scenario) | The current running scenario                 |
| [vu](/docs/k6/latest/javascript-api/k6-execution/#vu)             | The current VU and iteration                 |

## Example: log all context variables

If you want to experiment with what each context variable looks like as a test runs, you can copy this template literal into one of your test scripts.

Note that this omits the `abort` variable, since that function would abort the test.

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

```javascript
import exec from 'k6/execution';

export default function () {
  console.log(`Execution context

Instance info
-------------
Vus active: ${exec.instance.vusActive}
Iterations completed: ${exec.instance.iterationsCompleted}
Iterations interrupted:  ${exec.instance.iterationsInterrupted}
Iterations completed:  ${exec.instance.iterationsCompleted}
Iterations active:  ${exec.instance.vusActive}
Initialized vus:  ${exec.instance.vusInitialized}
Time passed from start of run(ms):  ${exec.instance.currentTestRunDuration}

Scenario info
-------------
Name of the running scenario: ${exec.scenario.name}
Executor type: ${exec.scenario.executor}
Scenario start timestamp: ${exec.scenario.startTime}
Percentage complete: ${exec.scenario.progress}
Iteration in instance: ${exec.scenario.iterationInInstance}
Iteration in test: ${exec.scenario.iterationInTest}

Test info
---------
All test options: ${exec.test.options}

VU info
-------
Iteration id: ${exec.vu.iterationInInstance}
Iteration in scenario: ${exec.vu.iterationInScenario}
VU ID in instance: ${exec.vu.idInInstance}
VU ID in test: ${exec.vu.idInTest}
VU tags: ${exec.vu.tags}`);
}
```

For detailed reference, refer to the [k6/execution module](/docs/k6/latest/javascript-api/k6-execution/).

## Additional examples

- [Getting unique data once](/docs/k6/latest/examples/data-parameterization/#retrieving-unique-data)
- [Timing operations](/docs/k6/latest/javascript-api/k6-execution/#timing-operations)
- [Executing different code blocks](/docs/k6/latest/javascript-api/k6-execution/#script-naming)

\_VU and \_ITER (discouraged)

> Note
> 
> k6 v0.34.0 introduced the **k6/execution** module. If you are using a version of k6 that doesn’t have this module, use `__VU` and `__ITER`.

`__VU` and `__ITER` are both global variables with execution-context information that k6 makes available to the test script.

- `__ITER`: A numeric counter with the current iteration number for a specific VU. Zero-based.
- `__VU`: Current VU number in use. k6 assigns the value incrementally for each new VU instance, starting from one. The variable is 0 when executing the setup and teardown functions.

### Running in k6 Cloud

When you run tests in [Grafana Cloud k6](/docs/grafana-cloud/testing/k6/), the **\_\_VU** value is per server/load generator.

### Examples

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

```javascript
import http from 'k6/http';
import { sleep } from 'k6';
export default function () {
  http.get('http://test.k6.io');
  console.log(`VU: ${__VU}  -  ITER: ${__ITER}`);
  sleep(1);
}
```

You can use execution-context variables to configure different test behaviors and parameterizations. A typical use case is a load test that simulates different users performing a login flow.

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

```javascript
import http from 'k6/http';
import { sleep } from 'k6';
export default function () {
  const email = `user+${__VU}@mail.com`;
  const payload = JSON.stringify({ email: email, password: 'test' });
  const params = { headers: { 'Content-Type': 'application/json' } };
  http.post('http://test.k6.io/login', payload, params);
  console.log(email);
  // .. continue the user flow
  sleep(1);
}
```

## Grafana Cloud k6 context variables

Grafana Cloud k6 injects additional context variables into a running cloud test. These variables provide information about the server (`K6_CLOUDRUN_INSTANCE_ID`), load zone (`K6_CLOUDRUN_LOAD_ZONE`),instance ID (`K6_CLOUDRUN_INSTANCE_ID`), and cloud distribution (`K6_CLOUDRUN_DISTRIBUTION`).

Refer to [Cloud execution context variables](/docs/grafana-cloud/testing/k6/author-run/cloud-scripting-extras/cloud-execution-context-variables/) for more details.