---
title: "Inject HTTP faults into Pod | Grafana k6 documentation"
description: "This example shows how to test the effect of faults injected in the HTTP requests served by a pod."
---

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

# Inject HTTP faults into Pod

This example shows how [PodDisruptor](/docs/k6/latest/testing-guides/injecting-faults-with-xk6-disruptor/xk6-disruptor/poddisruptor/) can be used for testing the effect of faults injected in the HTTP requests served by a pod.

You will find the complete [source code](#source-code) at the end of this document. Next sections examine the code in detail.

The example uses [httpbin](https://httpbin.org), a simple request/response application that offers endpoints for testing different HTTP requests.

The test requires `httpbin` to be deployed in a cluster in the namespace `httpbin` and exposed with an external IP. the IP address is expected in the environment variable `SVC_IP`.

You will find the Kubernetes manifests and the instructions of how to deploy it to a cluster in the [test setup](#test-setup) section at the end of this document. You can learn more about how to get the external IP address in the [expose your application](/docs/k6/latest/testing-guides/injecting-faults-with-xk6-disruptor/expose--your-application/) section.

## Initialization

The initialization code imports the external dependencies required by the test. The `PodDisruptor` class imported from the `xk6-disruptor` extension provides functions for injecting faults in pods. The [k6/http](/docs/k6/latest/javascript-api/k6-http/) module provides functions for executing HTTP requests.

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

```javascript
import { PodDisruptor } from 'k6/x/disruptor';
import http from 'k6/http';
```

## Test Load

The test load is generated by the `default` function, which executes a request to the `httpbin` pod using the IP obtained from the environment variable `SVC_IP`. The test makes requests to the endpoint `delay/0.1` which will return after `0.1` seconds (`100ms`).

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

```javascript
export default function (data) {
  http.get(`http://${data.SVC_IP}/delay/0.1`);
}
```

> Note
> 
> The test uses the `delay` endpoint which return after the requested delay. It requests a `0.1s` (`100ms`) delay to ensure the baseline scenario (see scenarios below) has meaningful statistics for the request duration. If we were simply calling a locally deployed http server (for example `nginx`), the response time would exhibit a large variation between a few microseconds to a few milliseconds. Having `100ms` as baseline response time has proved to offer more consistent results.

## Fault injection

The `disrupt` function creates a `PodDisruptor` using a selector that matches pods in the namespace `httpbin` with the label `app: httpbin`.

The http faults are injected by calling the [PodDisruptor.injectHTTPFaults](/docs/k6/latest/testing-guides/injecting-faults-with-xk6-disruptor/xk6-disruptor/poddisruptor/injecthttpfaults/) method using a fault definition that introduces a delay of `50ms` on each request and an error code `500` in `10%` of the requests.

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

```javascript
export function disrupt(data) {
  if (__ENV.SKIP_FAULTS == '1') {
    return;
  }
  const selector = {
    namespace: namespace,
    select: {
      labels: {
        app: 'httpbin',
      },
    },
  };
  const podDisruptor = new PodDisruptor(selector);
  // delay traffic from one random replica of the deployment
  const fault = {
    averageDelay: '50ms',
    errorCode: 500,
    errorRate: 0.1,
  };
  podDisruptor.injectHTTPFaults(fault, '30s');
}
```

Notice the following code snippet in the `injectFaults` function above:

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

```javascript
export function disrupt(data) {
  if (__ENV.SKIP_FAULTS == '1') {
    return;
  }
  //...
}
```

This code makes the function return without injecting faults if the `SKIP_FAULTS` environment variable is passed to the execution of the test with a value of “1”. We will use this option to obtain a [baseline execution](#baseline-execution) without faults.

## Scenarios

This test defines two [scenarios](/docs/k6/latest/using-k6/scenarios/) to be executed. The `load` scenario applies the test load to the `httpbin` application for `30s` invoking the `default` function. The `disrupt` scenario invokes the `disrupt` function to inject a fault in the HTTP requests of the target application.

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

```javascript
export const options = {
  scenarios: {
    load: {
      executor: 'constant-arrival-rate',
      rate: 100,
      preAllocatedVUs: 10,
      maxVUs: 100,
      exec: 'default',
      startTime: '0s',
      duration: '30s',
    },
    disrupt: {
      executor: 'shared-iterations',
      iterations: 1,
      vus: 1,
      exec: 'disrupt',
      startTime: '0s',
    },
  },
};
```

> Note
> 
> Notice that the `disrupt` scenario uses a `shared-iterations` executor with one iteration and one `VU`. This setting ensures the `disrupt` function is executed only once. Executing this function multiples times concurrently may have unpredictable results.

## Executions

> Note
> 
> The commands in this section assume the `xk6-disruptor` binary is available in your current directory. This location can change depending on the installation process and the platform. Refer to the [installation section](/docs/k6/latest/testing-guides/injecting-faults-with-xk6-disruptor/installation/) for details on how to install it in your environment.

### Baseline execution

We will first execute the test without introducing faults to have an baseline using the following command:

Bash windows-powershell

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

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

```bash
xk6-disruptor run --env SKIP_FAULTS=1 --env SVC_IP=$SVC_IP --summary-mode=legacy disrupt-pod.js
```

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

```windows-powershell
xk6-disruptor run --env SKIP_FAULTS=1 --env "SVC_IP=$Env:SVC_IP" --summary-mode=legacy disrupt-pod.js
```

Notice the argument `--env SKIP_FAULT=1`, which makes the `disrupt` function return without injecting any fault as explained in the [fault injection](#fault-injection) section. Also notice the `--env SVC_IP` argument, which passes the external IP used to access the `httpbin` application.

You should get an output similar to the one shown below (click `Expand` button to see all output).

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

```none
         /\      Grafana   /‾‾/
    /\  /  \     |\  __   /  /
   /  \/    \    | |/ /  /   ‾‾\
  /          \   |   (  |  (‾)  |
 / __________ \  |_|\_\  \_____/

  execution: local
     script: test.js
     output: -

  scenarios: (100.00%) 2 scenarios, 101 max VUs, 10m30s max duration (incl. graceful stop):
           * disrupt: 1 iterations shared among 1 VUs (maxDuration: 10m0s, exec: disrupt, gracefulStop: 30s)
           * load: 100.00 iterations/s for 30s (maxVUs: 10-100, exec: default, gracefulStop: 30s)


running (00m30.1s), 000/014 VUs, 2998 complete and 0 interrupted iterations
disrupt ✓ [======================================] 1 VUs        00m00.0s/10m0s  1/1 shared iters
load    ✓ [======================================] 000/013 VUs  30s             100.00 iters/s

     data_received..................: 1.4 MB 46 kB/s
     data_sent......................: 267 kB 8.9 kB/s
     dropped_iterations.............: 4      0.132766/s
     http_req_blocked...............: avg=8.08µs   min=2.36µs   med=5.8µs    max=543.79µs p(90)=8.68µs   p(95)=10.5µs
     http_req_connecting............: avg=1.25µs   min=0s       med=0s       max=418.63µs p(90)=0s       p(95)=0s
     http_req_duration..............: avg=103.22ms min=101.65ms med=103.13ms max=121.7ms  p(90)=104.01ms p(95)=104.4ms
       { expected_response:true }...: avg=103.22ms min=101.65ms med=103.13ms max=121.7ms  p(90)=104.01ms p(95)=104.4ms
     http_req_failed................: 0.00%  ✓ 0         ✗ 2997
     http_req_receiving.............: avg=133.5µs  min=45.06µs  med=131.23µs max=879.43µs p(90)=193.48µs p(95)=223.04µs
     http_req_sending...............: avg=31.14µs  min=11.46µs  med=29.37µs  max=171.68µs p(90)=40.48µs  p(95)=47.53µs
     http_req_tls_handshaking.......: avg=0s       min=0s       med=0s       max=0s       p(90)=0s       p(95)=0s
     http_req_waiting...............: avg=103.05ms min=101.54ms med=102.98ms max=121.56ms p(90)=103.82ms p(95)=104.2ms
     http_reqs......................: 2997   99.474844/s
     iteration_duration.............: avg=103.34ms min=109.86µs med=103.28ms max=121.92ms p(90)=104.19ms p(95)=104.63ms
     iterations.....................: 2998   99.508035/s
     vus............................: 13     min=11      max=13
     vus_max........................: 14     min=12      max=14
```

### Fault injection

We repeat the execution injecting the faults. Notice we have removed the `--env SKIP_FAULTS=1` argument.

Bash windows-powershell

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

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

```bash
xk6-disruptor run --env SVC_IP=$SVC_IP --summary-mode=legacy disrupt-pod.js
```

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

```windows-powershell
xk6-disruptor run --env "SVC_IP=$Env:SVC_IP" --summary-mode=legacy disrupt-pod.js
```

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

```none
         /\      Grafana   /‾‾/
    /\  /  \     |\  __   /  /
   /  \/    \    | |/ /  /   ‾‾\
  /          \   |   (  |  (‾)  |
 / __________ \  |_|\_\  \_____/

  execution: local
     script: disrupt-pod.js
     output: -

  scenarios: (100.00%) 2 scenarios, 101 max VUs, 10m30s max duration (incl. graceful stop):
           * disrupt: 1 iterations shared among 1 VUs (maxDuration: 10m0s, exec: disrupt, gracefulStop: 30s)
           * load: 100.00 iterations/s for 30s (maxVUs: 10-100, exec: default, gracefulStop: 30s)


running (00m31.1s), 000/018 VUs, 2995 complete and 0 interrupted iterations
disrupt ✓ [======================================] 1 VUs        00m31.1s/10m0s  1/1 shared iters
load    ✓ [======================================] 000/017 VUs  30s             100.00 iters/s

     data_received..................: 1.1 MB 34 kB/s
     data_sent......................: 267 kB 8.6 kB/s
     dropped_iterations.............: 7      0.224798/s
     http_req_blocked...............: avg=9.81µs   min=2.59µs   med=5.93µs   max=489.67µs p(90)=7.88µs   p(95)=9.5µs
     http_req_connecting............: avg=2.48µs   min=0s       med=0s       max=367.63µs p(90)=0s       p(95)=0s
     http_req_duration..............: avg=142.15ms min=50.33ms  med=153.79ms max=165.85ms p(90)=154.8ms  p(95)=155.12ms
       { expected_response:true }...: avg=151.9ms  min=101.81ms med=153.9ms  max=165.85ms p(90)=154.86ms p(95)=155.17ms
     http_req_failed................: 9.65%  ✓ 289       ✗ 2705
     http_req_receiving.............: avg=80.92µs  min=28.32µs  med=77.33µs  max=352.19µs p(90)=105.09µs p(95)=123.68µs
     http_req_sending...............: avg=30.43µs  min=11.27µs  med=29.37µs  max=287.71µs p(90)=37.42µs  p(95)=41.84µs
     http_req_tls_handshaking.......: avg=0s       min=0s       med=0s       max=0s       p(90)=0s       p(95)=0s
     http_req_waiting...............: avg=142.04ms min=50.25ms  med=153.68ms max=165.76ms p(90)=154.69ms p(95)=155.01ms
     http_reqs......................: 2994   96.149356/s
     iteration_duration.............: avg=152.64ms min=50.43ms  med=153.93ms max=31.12s   p(90)=154.97ms p(95)=155.29ms
     iterations.....................: 2995   96.18147/s
     vus............................: 1      min=1       max=18
     vus_max........................: 18     min=12      max=18
```

### Comparison

Let’s take a closer look at the results for the requests on each scenario. We can observe that he `base` scenario has an average of `103ms` and an error rate of `0%` while the `faults` scenario has a median around `151.9ms` and an error rate of nearly `10%`, matching the definition of the faults defined in the disruptor.

Expand table

| Execution       | Avg. Response | Failed requests |
|-----------------|---------------|-----------------|
| Baseline        | 103.22ms      | 0.00%           |
| Fault injection | 151.9 ms      | 9.65%           |

> Note
> 
> Notice we have used the average response time reported as `expected_response:true` because this metric only consider successful requests while `http_req_duration` considers all requests, including those returning a fault.

## Source Code

disrupt-pod.js

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

```javascript
import { PodDisruptor } from 'k6/x/disruptor';
import http from 'k6/http';

export default function (data) {
  http.get(`http://${__ENV.SVC_IP}/delay/0.1`);
}

export function disrupt(data) {
  if (__ENV.SKIP_FAULTS == '1') {
    return;
  }

  const selector = {
    namespace: 'httpbin',
    select: {
      labels: {
        app: 'httpbin',
      },
    },
  };
  const podDisruptor = new PodDisruptor(selector);

  // delay traffic from one random replica of the deployment
  const fault = {
    averageDelay: '50ms',
    errorCode: 500,
    errorRate: 0.1,
  };
  podDisruptor.injectHTTPFaults(fault, '30s');
}

export const options = {
  scenarios: {
    load: {
      executor: 'constant-arrival-rate',
      rate: 100,
      preAllocatedVUs: 10,
      maxVUs: 100,
      exec: 'default',
      startTime: '0s',
      duration: '30s',
    },
    disrupt: {
      executor: 'shared-iterations',
      iterations: 1,
      vus: 1,
      exec: 'disrupt',
      startTime: '0s',
    },
  },
};
```

## Test setup

The tests requires the deployment of the `httpbin` application. The application must also be accessible using an external IP available in the `SVC_IP` environment variable.

The [manifests](#manifests) below define the resources required for deploying the application and exposing it as a LoadBalancer service.

You can deploy the application using the following commands:

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

```bash
# Create Namespace
kubectl apply -f namespace.yaml
namespace/httpbin created

# Deploy Pod
kubectl apply -f pod.yaml
pod/httpbin created

# Expose Pod as a Service
kubectl apply -f service.yaml
service/httpbin created
```

You can retrieve the resources using the following command:

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

```bash
kubectl -n httpbin get all
NAME          READY   STATUS    RESTARTS   AGE
pod/httpbin   1/1     Running   0          1m

NAME              TYPE           CLUSTER-IP     EXTERNAL-IP      PORT(S)        AGE
service/httpbin   LoadBalancer   10.96.169.78   172.18.255.200   80:31224/TCP   1m
```

You must set the environment variable `SVC_IP` with the external IP address and port used to access the `httpbin` service from the test script.

You can learn more about how to get the external IP address in the [expose your application](/docs/k6/latest/testing-guides/injecting-faults-with-xk6-disruptor/expose--your-application/) section.

### Manifests

namespace.yaml

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

```yaml
apiVersion: 'v1'
kind: Namespace
metadata:
  name: httpbin
```

pod.yaml

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

```yaml
kind: 'Pod'
apiVersion: 'v1'
metadata:
  name: httpbin
  namespace: httpbin
  labels:
    app: httpbin
spec:
  containers:
    - name: httpbin
      image: kennethreitz/httpbin
      ports:
        - name: http
          containerPort: 80
```

service.yaml

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

```yaml
apiVersion: 'v1'
kind: 'Service'
metadata:
  name: httpbin
  namespace: httpbin
spec:
  selector:
    app: httpbin
  type: 'LoadBalancer'
  ports:
    - port: 80
      targetPort: 80
```