k6 Cheat Sheet

Installation

macOSbrew install k6
Windowschoco install k6
Linuxsnap install k6
Dockerdocker pull grafana/k6
npmnpm i -g @grafana/k6

Basic Script Structure

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

export const options = {
  vus: 10,              // Virtual Users
  duration: '30s',       // Test duration
};

export default function() {
  const res = http.get('https://test-api.k6.io');
  check(res, { 'status is 200': (r) => r.status === 200 });
  sleep(1);
}
          

CLI Commands

k6 runExecute test script
k6 cloudRun on k6 Cloud
k6 inspectInspect script
k6 versionShow version
--vusVirtual users
--durationTest duration

HTTP Methods

http.get()GET request
http.post()POST request
http.put()PUT request
http.del()DELETE request
http.patch()PATCH request
http.batch()Parallel requests

Test Options

vusVirtual users count
durationTest duration
iterationsTotal iterations
stagesRamp up/down
thresholdsPass/fail criteria

Checks & Assertions

check(res, {
  'status 200': (r) => r.status === 200,
  'body size': (r) => r.body.length > 0,
  'duration': (r) => r.timings.duration < 500,
  'has header': (r) => r.headers['Content-Type'],
});
          

Load Stages (Ramp Up/Down)

export const options = {
  stages: [
    { duration: '2m', target: 100 },   // Ramp up to 100 users
    { duration: '5m', target: 100 },   // Stay at 100 users
    { duration: '2m', target: 0 },     // Ramp down to 0
  ],
};
          

Thresholds (Pass/Fail Criteria)

export const options = {
  thresholds: {
    http_req_duration: ['p(95)<500'],      // 95% under 500ms
    http_req_failed: ['rate<0.01'],        // Error rate under 1%
    checks: ['rate>0.99'],                  // 99% checks pass
    http_reqs: ['rate>100'],                 // Min 100 req/s
  },
};
          

Built-in Metrics

http_reqsTotal requests
http_req_durationResponse time
http_req_failedFailed requests
iterationsCompleted iterations
vusActive VUs
data_receivedData downloaded

POST JSON Data

const payload = JSON.stringify({
  username: 'test',
  password: 'secret'
});

const params = {
  headers: {
    'Content-Type': 'application/json'
  }
};

http.post(url, payload, params);
          

Output & Reporting

# Output to JSON
k6 run --out json=results.json script.js

# Output to InfluxDB
k6 run --out influxdb=http://localhost:8086/k6 script.js

# Output to CSV
k6 run --out csv=results.csv script.js

# Multiple outputs
k6 run --out json=out.json --out influxdb=http://localhost:8086/k6 script.js
          

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