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)

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.

Permissions required

Below is a sample Kubernetes role that defines the permissions required to execute the fault.

apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  namespace: hce
  name: k6-loadgen
spec:
  definition:
    scope: Namespaced # Supports "Cluster" mode too
permissions:
  - apiGroups: [""]
    resources: ["pods"]
    verbs: ["create", "delete", "get", "list", "patch", "deletecollection", "update"]
  - apiGroups: [""]
    resources: ["events"]
    verbs: ["create", "get", "list", "patch", "update"]
  - apiGroups: [""]
    resources: ["pods/log"]
    verbs: ["get", "list", "watch"]
  - apiGroups: [""]
    resources: ["deployments"]
    verbs: ["get", "list"]
  - apiGroups: [""]
    resources: ["chaosEngines", "chaosExperiments", "chaosResults"]
    verbs: ["create", "delete", "get", "list", "patch", "update"]
  - apiGroups: ["batch"]
    resources: ["jobs"]
    verbs: ["create", "delete", "get", "list", "deletecollection"]
  - apiGroups: [""]
    resources: ["configmaps", "secrets"]
    verbs: ["get", "list", "watch"]

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