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K6 loadgen

K6 loadgen fault simulates load generation on the target hosts for a specific chaos duration. This fault:

  • Slows down or makes the target host unavailable due to heavy load.
  • Checks the performance of the application or process running on the instance.
  • Supports various types of load testing (ex. spike, smoke, stress)

k6 Loadgen Chaos

Use cases​

  • Simulate high traffic to test the performance and reliability of RESTful APIs.
  • Automate performance testing in CI/CD pipelines to catch regressions early.
  • Evaluate the behavior of web applications under heavy user loads.
  • Continuously monitor cloud infrastructure performance by generating synthetic traffic.

Prerequisites​

  • Kubernetes > 1.17 is required to execute this fault.
  • The target host should be accessible.
  • Ensure to create a Kubernetes secret that contains the javascript (JS) file within the Chaos Infrastructure's namespace. The easiest way to create a secret object is as follows::

An example of the JS file is as follows:

import http from 'k6/http';
import { check, sleep } from 'k6';

export default function () {
  let res = http.get('https://google.com');

  check(res, { 'status is 200': (r) => r.status === 200 });

  sleep(0.3);
}
kubectl create secret generic k6-script \
--from-file=<<script-path>> -n <<chaos_infrastructure_namespace>>

Mandatory tunables​

Tunable Description Notes
SCRIPT_SECRET_NAME Provide the k8s secret name of the JS script to run k6. Default to k6-script. For more information, go to k6 secret
SCRIPT_SECRET_KEY Provide the key of the k8s secret named SCRIPT_SECRET_NAME Default to script.js. For more information, go to k6 secret

Optional tunables​

Tunable Description Notes
TOTAL_CHAOS_DURATION The time duration for chaos injection (in seconds). Default: 60s. For more information, go to duration of the chaos.
LOAD_IMAGE Image used in helper pod that contains the chaos injection logic. Default: ghcr.io/grafana/k6-operator:latest-runner. For more information, go to custom load image.
RAMP_TIME Wait period before and after injecting chaos (in seconds). For example, 30s. For more information, go to ramp time.

K6 Secret​

It defines the secret and key names for the k6 load generation script. You can adjust them using the SCRIPT_SECRET_NAME and SCRIPT_SECRET_KEY environment variables, respectively..

The following YAML snippet illustrates the use of this environment variable:

apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: load-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: k6-load-generator
    spec:
      components:
        env:
        - name: SCRIPT_SECRET_NAME
          value: 'k6-script'
        - name: SCRIPT_SECRET_KEY
          value: 'script.js'

Custom load image​

Image of the k6 load generator. Tune it by using the LOAD_IMAGE environment variable.

The following YAML snippet illustrates the use of this environment variable:

# provid a custom image for load generation
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: load-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: k6-load-generator
    spec:
      components:
        env:
        - name: LOAD_IMAGE
          value: ghcr.io/grafana/k6-operator:latest-runner