Distributed Tests

Distributed testing allows you to run a single k6 test across multiple machines, enabling higher load generation and testing from multiple IP addresses. This guide covers using the k6 Kubernetes operator to orchestrate distributed tests.

When to Use Distributed Tests

Consider distributed testing when:

High Load Requirements

A single optimized node cannot generate the load your test requires

Multiple IP Addresses

Your system under test needs to be accessed from different IP addresses

Geographic Distribution

You need to test from multiple geographic locations simultaneously

Kubernetes Environment

Kubernetes is already your preferred operations environment

Introducing k6-operator

The k6-operator is a Kubernetes operator that automates distributed k6 test execution. It defines a custom TestRun resource that specifies:

The k6 test script to execute
The number of parallel pods (parallelism)
Environment configuration
Resource allocation

When you create a TestRun, the operator automatically provisions k6 test jobs across your cluster, splitting the workload using execution segments.

Getting Started

Prerequisites

Access to a Kubernetes cluster
kubectl installed and configured
Appropriate cluster permissions

You can experiment locally using kind or k3d to run Kubernetes in Docker.

Step 1: Install the Operator

Install the k6-operator in your cluster:

curl https://raw.githubusercontent.com/grafana/k6-operator/main/bundle.yaml | kubectl apply -f -

Verify the installation:

kubectl get pod -n k6-operator-system

You should see:

NAME                                              READY   STATUS    RESTARTS   AGE
k6-operator-controller-manager-7664957cf7-llw54   2/2     Running   0          160m

Step 2: Create a Test Script

Create your k6 test script (same as for local testing):

test.js

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

export const options = {
  vus: 10,
  duration: '10s',
};

export default function () {
  http.get('https://test.k6.io/');
  sleep(1);
}

Always validate your script locally with k6 run test.js before deploying to Kubernetes.

Step 3: Add Test Script to Kubernetes

You can provide test scripts to the operator using either ConfigMaps or PersistentVolumes.

ConfigMap (Recommended)
PersistentVolume

Create a ConfigMap from your test file:

kubectl create configmap my-test --from-file test.js

Limitations: ConfigMaps have a 1 MiB size limit. For larger scripts, use PersistentVolumes.

For larger test suites or modular scripts:

Create a PersistentVolume and PersistentVolumeClaim
Copy test scripts to the volume under /test/ directory
Reference the claim in your TestRun

See Kubernetes PersistentVolumes documentation for details.

Step 4: Create a TestRun Resource

Define a TestRun custom resource to execute your test:

From ConfigMap
From PersistentVolume

run-k6-from-configmap.yaml

apiVersion: k6.io/v1alpha1
kind: TestRun
metadata:
  name: run-k6-from-configmap
spec:
  parallelism: 4
  script:
    configMap:
      name: my-test
      file: test.js

This configuration:

Runs the test across 4 parallel pods
Loads script from the my-test ConfigMap
Automatically splits the workload using execution segments

run-k6-from-volume.yaml

apiVersion: k6.io/v1alpha1
kind: TestRun
metadata:
  name: run-k6-from-volume
spec:
  parallelism: 4
  script:
    volumeClaim:
      name: my-volume-claim
      file: test.js  # Relative to /test/ directory

The ConfigMap/PersistentVolumeClaim and TestRun must be in the same Kubernetes namespace.

Advanced Configuration

Environment Variables

Pass configuration through environment variables:

apiVersion: k6.io/v1alpha1
kind: TestRun
metadata:
  name: run-k6-with-vars
spec:
  parallelism: 4
  script:
    configMap:
      name: my-test
      file: test.js
  runner:
    env:
      - name: TARGET_URL
        value: 'https://test.k6.io'
      - name: VUS
        value: '50'
    envFrom:
      - configMapRef:
          name: my-config-vars
      - secretRef:
          name: my-secrets

Use in your test script:

const baseUrl = __ENV.TARGET_URL || 'https://default.com';
const vus = __ENV.VUS || 10;

export const options = {
  vus: parseInt(vus),
  duration: '30s',
};

export default function () {
  http.get(baseUrl);
}

Command-Line Arguments

Pass k6 options via command-line arguments:

apiVersion: k6.io/v1alpha1
kind: TestRun
metadata:
  name: run-k6-with-args
spec:
  parallelism: 4
  script:
    configMap:
      name: my-test
      file: test.js
  arguments: --tag testid=distributed-001 --log-format json --out experimental-prometheus-rw

Resource Limits

Control pod resources:

apiVersion: k6.io/v1alpha1
kind: TestRun
metadata:
  name: run-k6-with-resources
spec:
  parallelism: 4
  script:
    configMap:
      name: my-test
      file: test.js
  runner:
    resources:
      limits:
        cpu: 1000m
        memory: 1Gi
      requests:
        cpu: 500m
        memory: 512Mi

Automatic Cleanup

Automatically remove test resources after completion:

apiVersion: k6.io/v1alpha1
kind: TestRun
metadata:
  name: run-k6-with-cleanup
spec:
  parallelism: 4
  cleanup: post  # Remove all resources after test completes
  script:
    configMap:
      name: my-test
      file: test.js
  arguments: -o experimental-prometheus-rw

Use cleanup: post when outputting to real-time services like Prometheus, Grafana Cloud k6, or other external outputs.

Running Tests

Apply the TestRun

Deploy your test configuration:

kubectl apply -f run-k6-from-configmap.yaml

Monitor execution

Watch test progress:

# Watch pods
kubectl get pods -w

# View test logs
kubectl logs -f <pod-name>

# Check TestRun status
kubectl get testrun run-k6-from-configmap

Clean up resources

After the test completes:

kubectl delete -f run-k6-from-configmap.yaml

Or use cleanup: post in the TestRun spec for automatic cleanup.

Complete Example

Here’s a comprehensive distributed test setup:

distributed-load-test.yaml

apiVersion: k6.io/v1alpha1
kind: TestRun
metadata:
  name: distributed-load-test
spec:
  parallelism: 8  # Split across 8 pods
  cleanup: post
  script:
    configMap:
      name: load-test-script
      file: test.js
  arguments: |
    --tag testid=distributed-load-001
    --out experimental-prometheus-rw
    --log-format json
  runner:
    env:
      - name: K6_PROMETHEUS_RW_SERVER_URL
        value: 'http://prometheus:9090/api/v1/write'
      - name: TARGET_VUS
        value: '800'
      - name: TEST_DURATION
        value: '5m'
    envFrom:
      - secretRef:
          name: api-credentials
    resources:
      limits:
        cpu: 2000m
        memory: 2Gi
      requests:
        cpu: 1000m
        memory: 1Gi

Corresponding test script:

test.js

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

const errorRate = new Rate('errors');

export const options = {
  stages: [
    { duration: '1m', target: parseInt(__ENV.TARGET_VUS) * 0.5 },
    { duration: __ENV.TEST_DURATION, target: parseInt(__ENV.TARGET_VUS) },
    { duration: '1m', target: 0 },
  ],
  thresholds: {
    http_req_duration: ['p(95)<500'],
    errors: ['rate<0.01'],
  },
};

export default function () {
  const res = http.get(__ENV.TARGET_URL || 'https://test.k6.io');
  
  const success = check(res, {
    'status is 200': (r) => r.status === 200,
  });
  
  errorRate.add(!success);
  sleep(1);
}

Monitoring Distributed Tests

Using Prometheus

apiVersion: k6.io/v1alpha1
kind: TestRun
metadata:
  name: monitored-test
spec:
  parallelism: 4
  cleanup: post
  script:
    configMap:
      name: my-test
      file: test.js
  arguments: --out experimental-prometheus-rw
  runner:
    env:
      - name: K6_PROMETHEUS_RW_SERVER_URL
        value: 'http://prometheus-server:9090/api/v1/write'
      - name: K6_PROMETHEUS_RW_TREND_AS_NATIVE_HISTOGRAM
        value: 'true'

Using Grafana Cloud k6

apiVersion: k6.io/v1alpha1
kind: TestRun
metadata:
  name: cloud-monitored-test
spec:
  parallelism: 4
  cleanup: post
  script:
    configMap:
      name: my-test
      file: test.js
  arguments: --out cloud
  runner:
    envFrom:
      - secretRef:
          name: k6-cloud-token

Troubleshooting

Pods not starting

Check pod events and logs:

kubectl describe pod <pod-name>
kubectl logs <pod-name>

Common issues:

ConfigMap not found in namespace
Insufficient cluster resources
Image pull errors

Test execution errors

View test runner logs:

kubectl logs -l k6_cr=<testrun-name>

Check for:

Script errors (syntax, logic)
Network connectivity issues
Resource constraints

Workload not splitting correctly

Verify execution segments:

# Check if pods are using different segments
kubectl logs <pod-name> | grep segment

Ensure parallelism is set correctly in the TestRun spec.

Results not aggregating

For distributed tests, use external outputs:

Prometheus Remote Write
Grafana Cloud k6
InfluxDB
Other supported outputs

Local console output won’t aggregate across pods.

Best Practices

Test Locally First

Always validate scripts with k6 run before deploying to Kubernetes

Use External Outputs

Configure real-time outputs for aggregated metrics across all pods

Set Resource Limits

Define appropriate CPU and memory limits to prevent cluster overload

Enable Cleanup

Use cleanup: post to automatically remove completed test resources

Monitor During Tests

Watch pod logs and metrics in real-time to catch issues early

Version Test Scripts

Store test scripts in version control and use ConfigMaps for deployment

Example: High-Scale Distributed Test

high-scale-test.yaml

apiVersion: k6.io/v1alpha1
kind: TestRun
metadata:
  name: high-scale-test
spec:
  parallelism: 20  # 20 pods for maximum distribution
  cleanup: post
  script:
    volumeClaim:
      name: test-scripts-pvc
      file: high-scale-test.js
  arguments: |
    --out experimental-prometheus-rw
    --tag environment=staging
    --tag test=high-scale
    --summary-trend-stats="min,avg,med,p(90),p(95),p(99),max"
  runner:
    env:
      - name: K6_PROMETHEUS_RW_SERVER_URL
        valueFrom:
          configMapKeyRef:
            name: monitoring-config
            key: prometheus-url
      - name: TEST_VUS
        value: '10000'  # 10k VUs distributed across 20 pods
      - name: TEST_DURATION
        value: '30m'
    resources:
      limits:
        cpu: 4000m
        memory: 4Gi
      requests:
        cpu: 2000m
        memory: 2Gi

With parallelism: 20 and TEST_VUS: 10000, each pod will run ~500 VUs. Adjust based on your pod resource limits and cluster capacity.

Next Steps

Learn about k6 scenarios for advanced execution control
Explore k6 outputs for metrics storage
Check the k6-operator documentation for advanced features
Join the k6 Community Forum for help and discussions

Using k6

Testing Guides

Browser Testing

Results & Visualization

When to Use Distributed Tests

High Load Requirements

Multiple IP Addresses

Geographic Distribution

Kubernetes Environment

Introducing k6-operator

Getting Started

Prerequisites

Step 1: Install the Operator

Step 2: Create a Test Script

Step 3: Add Test Script to Kubernetes

Step 4: Create a TestRun Resource

Advanced Configuration

Environment Variables

Command-Line Arguments

Resource Limits

Automatic Cleanup

Running Tests

Complete Example

Monitoring Distributed Tests

Using Prometheus

Using Grafana Cloud k6

Troubleshooting

Best Practices

Test Locally First

Use External Outputs

Set Resource Limits

Enable Cleanup

Monitor During Tests

Version Test Scripts

Example: High-Scale Distributed Test

Next Steps

Build docs developers (and LLMs) love

Using k6

Testing Guides

Browser Testing

Results & Visualization

​When to Use Distributed Tests

High Load Requirements

Multiple IP Addresses

Geographic Distribution

Kubernetes Environment

​Introducing k6-operator

​Getting Started

​Prerequisites

​Step 1: Install the Operator

​Step 2: Create a Test Script

​Step 3: Add Test Script to Kubernetes

​Step 4: Create a TestRun Resource

​Advanced Configuration

​Environment Variables

​Command-Line Arguments

​Resource Limits

​Automatic Cleanup

​Running Tests

​Complete Example

​Monitoring Distributed Tests

​Using Prometheus

​Using Grafana Cloud k6

​Troubleshooting

​Best Practices

Test Locally First

Use External Outputs

Set Resource Limits

Enable Cleanup

Monitor During Tests

Version Test Scripts

​Example: High-Scale Distributed Test

​Next Steps

Build docs developers (and LLMs) love

When to Use Distributed Tests

Introducing k6-operator

Getting Started

Prerequisites

Step 1: Install the Operator

Step 2: Create a Test Script

Step 3: Add Test Script to Kubernetes

Step 4: Create a TestRun Resource

Advanced Configuration

Environment Variables

Command-Line Arguments

Resource Limits

Automatic Cleanup

Running Tests

Complete Example

Monitoring Distributed Tests

Using Prometheus

Using Grafana Cloud k6

Troubleshooting

Best Practices

Example: High-Scale Distributed Test

Next Steps