MCPInstall

k6-load-test

by dengineproblemTesting & QA

Эксперт k6 нагрузочного тестирования. Используй для performance testing, load scenarios и stress tests.

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Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/dengineproblem/agents-monorepo --skill k6-load-test
  1. 01

    Install

    Run the command in your project. The CLI asks which agents to install for.

  2. 02

    Describe the task

    Ask your agent for something this skill covers. It loads k6-load-test automatically when relevant.

  3. 03

    Review the result

    The agent follows the SKILL.md steps, scripts and references bundled with the skill.

SKILL.md

The instructions your agent reads when the skill is triggered.

k6 Load Testing Expert

Expert in performance testing with k6 framework.

Core k6 Principles

  • Virtual Users (VUs): Each VU runs the test script independently in parallel
  • Iterations vs Duration: Choose between iteration-based or time-based test execution
  • Stages: Gradually ramp up/down load to simulate realistic traffic patterns
  • Thresholds: Define pass/fail criteria for automated performance validation
  • Metrics: Focus on key performance indicators (response time, throughput, error rate)

Basic Test Script Structure

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

// Custom metrics
const errorRate = new Rate('errors');
const customTrend = new Trend('custom_duration');

// Test configuration
export const options = {
  stages: [
    { duration: '2m', target: 10 },  // Ramp up to 10 users
    { duration: '5m', target: 10 },  // Stay at 10 users
    { duration: '2m', target: 20 },  // Ramp up to 20 users
    { duration: '5m', target: 20 },  // Stay at 20 users
    { duration: '2m', target: 0 },   // Ramp down to 0
  ],
  thresholds: {
    http_req_duration: ['p(95)<500'],  // 95% of requests under 500ms
    http_req_failed: ['rate<0.1'],     // Error rate under 10%
    errors: ['rate<0.1'],
  },
};

// Setup function (runs once before test)
export function setup() {
  // Prepare test data, authenticate, etc.
  const loginRes = http.post('https://api.example.com/auth/login', {
    email: 'test@example.com',
    password: 'password123',
  });

  return { token: loginRes.json('token') };
}

// Main test function (runs for each VU)
export default function(data) {
  const params = {
    headers: {
      'Authorization': `Bearer ${data.token}`,
      'Content-Type': 'application/json',
    },
  };

  const response = http.get('https://api.example.com/users', params);

  // Verify response
  check(response, {
    'status is 200': (r) => r.status === 200,
    'response time < 500ms': (r) => r.timings.duration < 500,
    'response body contains users': (r) => r.body.includes('users'),
  });

  // Track custom metrics
  errorRate.add(response.status !== 200);
  customTrend.add(response.timings.duration);

  // Think time between requests
  sleep(Math.random() * 2 + 1); // 1-3 seconds
}

// Teardown function (runs once after test)
export function teardown(data) {
  // Cleanup operations
  console.log('Test completed');
}

Test Scenario Patterns

Load Test (Normal Traffic)

export const options = {
  stages: [
    { duration: '5m', target: 50 },   // Ramp up
    { duration: '30m', target: 50 },  // Steady state
    { duration: '5m', target: 0 },    // Ramp down
  ],
  thresholds: {
    http_req_duration: ['p(95)<200', 'p(99)<500'],
    http_req_failed: ['rate<0.01'],
  },
};

Stress Test (Beyond Normal Capacity)

export const options = {
  stages: [
    { duration: '2m', target: 100 },
    { duration: '5m', target: 100 },
    { duration: '2m', target: 200 },
    { duration: '5m', target: 200 },
    { duration: '2m', target: 300 },  // Beyond normal capacity
    { duration: '5m', target: 300 },
    { duration: '10m', target: 400 }, // Breaking point
    { duration: '2m', target: 0 },
  ],
};

Spike Test (Sudden Traffic Surge)

export const options = {
  stages: [
    { duration: '10s', target: 100 },  // Quick ramp-up
    { duration: '1m', target: 100 },   // Stay at peak
    { duration: '10s', target: 0 },    // Quick ramp-down
  ],
};

Soak Test (Extended Duration)

export const options = {
  stages: [
    { duration: '5m', target: 50 },
    { duration: '4h', target: 50 },   // Run for 4 hours
    { duration: '5m', target: 0 },
  ],
};

Breakpoint Test (Find Limits)

export const options = {
  executor: 'ramping-arrival-rate',
  stages: [
    { duration: '2m', target: 100 },
    { duration: '2m', target: 200 },
    { duration: '2m', target: 300 },
    { duration: '2m', target: 400 },
    { duration: '2m', target: 500 },
    // Continue until system breaks
  ],
};

Advanced Patterns

Data-Driven Testing

import { SharedArray } from 'k6/data';
import papaparse from 'https://jslib.k6.io/papaparse/5.1.1/index.js';

// Load CSV data once, share across VUs
const csvData = new SharedArray('users', function() {
  return papaparse.parse(open('./users.csv'), { header: true }).data;
});

export default function() {
  // Random user from dataset
  const user = csvData[Math.floor(Math.random() * csvData.length)];

  const payload = JSON.stringify({
    username: user.username,
    password: user.password,
  });

  const response = http.post('https://api.example.com/login', payload, {
    headers: { 'Content-Type': 'application/json' },
  });

  check(response, {
    'login successful': (r) => r.status === 200,
    'token present': (r) => r.json('token') !== '',
  });
}

Session-Based Testing with Groups

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

export default function() {
  let authToken;

  group('Authentication', function() {
    const loginRes = http.post('https://api.example.com/auth/login', {
      email: 'user@example.com',
      password: 'password123',
    });

    check(loginRes, { 'login successful': (r) => r.status === 200 });
    authToken = loginRes.json('token');
  });

  const headers = { Authorization: `Bearer ${authToken}` };

  group('Browse Products', function() {
    const productsRes = http.get('https://api.example.com/products', { headers });
    check(productsRes, { 'products loaded': (r) => r.status === 200 });

    const productId = productsRes.json('products')[0].id;
    const detailRes = http.get(`https://api.example.com/products/${productId}`, { headers });
    check(detailRes, { 'product detail loaded': (r) => r.status === 200 });
  });

  group('Add to Cart', function() {
    const cartRes = http.post('https://api.example.com/cart',
      JSON.stringify({ productId: 1, quantity: 2 }),
      { headers: { ...headers, 'Content-Type': 'application/json' } }
    );
    check(cartRes, { 'added to cart': (r) => r.status === 200 });
  });

  group('Checkout', function() {
    const checkoutRes = http.post('https://api.example.com/checkout',
      JSON.stringify({ paymentMethod: 'card' }),
      { headers: { ...headers, 'Content-Type': 'application/json' } }
    );
    check(checkoutRes, { 'checkout successful': (r) => r.status === 200 });
  });

  sleep(1);
}

Batch Requests

import http from 'k6/http';

export default function() {
  const responses = http.batch([
    ['GET', 'https://api.example.com/users'],
    ['GET', 'https://api.example.com/products'],
    ['GET', 'https://api.example.com/orders'],
    ['POST', 'https://api.example.com/events', JSON.stringify({ event: 'page_view' }), {
      headers: { 'Content-Type': 'application/json' },
    }],
  ]);

  check(responses[0], { 'users status 200': (r) => r.status === 200 });
  check(responses[1], { 'products status 200': (r) => r.status === 200 });
  check(responses[2], { 'orders status 200': (r) => r.status === 200 });
}

Custom Metrics

import { Counter, Gauge, Rate, Trend } from 'k6/metrics';

// Define custom metrics
const pageViews = new Counter('page_views');
const activeUsers = new Gauge('active_users');
const errorRate = new Rate('error_rate');
const responseTrend = new Trend('response_trend');

export default function() {
  const response = http.get('https://api.example.com/page');

  // Record metrics
  pageViews.add(1);
  activeUsers.add(__VU);  // Current VU count
  errorRate.add(response.status !== 200);
  responseTrend.add(response.timings.duration);

  // Tags for segmentation
  pageViews.add(1, { page: 'home', version: 'v2' });
}

Environment Configuration

Command Line Options

# Basic run
k6 run script.js

# Specify VUs and duration
k6 run --vus 50 --duration 10m script.js

# Environment variables
k6 run --env BASE_URL=https://staging.api.com --env API_KEY=xxx script.js

# Output to different backends
k6 run --out influxdb=http://localhost:8086/k6 script.js
k6 run --out json=results.json script.js
k6 run --out csv=results.csv script.js

# Cloud execution
k6 cloud script.js

# Run with config file
k6 run --config config.json script.js

Environment Variables in Script

const BASE_URL = __ENV.BASE_URL || 'https://api.example.com';
const API_KEY = __ENV.API_KEY || 'default-key';
const ENVIRONMENT = __ENV.ENV || 'staging';

export default function() {
  const response = http.get(`${BASE_URL}/endpoint`, {
    headers: { 'X-API-Key': API_KEY },
  });
}

CI/CD Integration

GitHub Actions

name: Load Test

on:
  push:
    branches: [main]
  schedule:
    - cron: '0 2 * * *'  # Daily at 2 AM

jobs:
  load-test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Install k6
        run: |
          curl -L https://github.com/grafana/k6/releases/download/v0.47.0/k6-v0.47.0-linux-amd64.tar.gz | tar xvz
          sudo mv k6-v0.47.0-linux-amd64/k6 /usr/local/bin/

      - name: Run load test
        run: k6 run --env BASE_URL=${{ secrets.API_URL }} tests/load-test.js

      - name: Upload results
        uses: actions/upload-artifact@v3
        with:
          name: k6-results
          path: results.json

Debugging and Analysis

import { textSummary } from 'https://jslib.k6.io/k6-summary/0.0.1/index.js';

// Custom summary handler
export function handleSummary(data) {
  return {
    'stdout': textSummary(data, { indent: ' ', enableColors: true }),
    'summary.json': JSON.stringify(data),
  };
}

export default function() {
  const response = http.get('https://api.example.com/data');

  // Detailed debugging on failure
  if (!check(response, { 'status is 200': (r) => r.status === 200 })) {
    console.error(`Request failed: ${response.status}`);
    console.error(`Response body: ${response.body.substring(0, 500)}`);
    console.error(`Request URL: ${response.request.url}`);
  }

  // Log slow requests
  if (response.timings.duration > 1000) {
    console.warn(`Slow request: ${response.timings.duration}ms - ${response.request.url}`);
  }
}

Key Metrics Reference

MetricDescriptionTypical Threshold
http_req_durationResponse timep(95)<500ms
http_req_failedFailed request raterate<0.01
http_reqsRequests per secondN/A (informational)
http_req_waitingTime to first bytep(95)<200ms
vusActive virtual usersN/A
iterationsCompleted iterationsN/A

Лучшие практики

  1. Realistic think time — добавляйте sleep() между запросами
  2. Gradual ramp-up — избегайте мгновенной нагрузки
  3. SharedArray for data — экономит память при больших датасетах
  4. Meaningful thresholds — определяйте SLO заранее
  5. Tags for segmentation — группируйте метрики по endpoint/feature
  6. Monitor load generator — убедитесь, что k6 не bottleneck

FAQ

What does the k6-load-test skill do?

Эксперт k6 нагрузочного тестирования. Используй для performance testing, load scenarios и stress tests.

How do I install k6-load-test?

Run npx skills add https://github.com/dengineproblem/agents-monorepo --skill k6-load-test in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/k6-load-test/ (personal) or .claude/skills/k6-load-test/ (project).

Which AI agents can use k6-load-test?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is k6-load-test safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Who maintains k6-load-test?

It is published by dengineproblem in dengineproblem/agents-monorepo. It has 181 recorded installs.

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