# curl https://devtools.krishanchawla.com/raw/k6-load-testing-cheatsheet.txt

K6 LOAD TESTING CHEATSHEET
Enterprise-ready K6 performance testing cheatsheet with commands, scripts, thresholds, and CI usage

Category: Testing · Type: cheatsheet
Official docs: https://k6.io/

────────────────────────────────────────────────────────────

## What is K6?

**K6** is a modern, developer-friendly load testing tool built for testing the performance of APIs, microservices, and websites. Write tests in JavaScript and run them from the CLI or CI/CD pipeline.

**⚡ Key Features**
- JavaScript-based test scripts
- Virtual users and load stages
- Performance thresholds (SLOs)
- Metrics and assertions
- Cloud and local execution

**🎯 Use Cases**
- API performance testing
- Load and stress testing
- Spike and soak testing
- CI/CD integration
- Performance regression detection

---

## 🛠️ Interactive Command Builder

Build a `k6 run` command without memorizing flag order — fill in the fields below and copy the result.

## 📥 K6 - Installation

Install K6 on different operating systems.

### macOS
```bash
brew install k6
```

### Linux (Debian / Ubuntu)
```bash
sudo apt update
sudo apt install k6
```

### Windows
```bash
choco install k6
```

Verify installation:
```bash
k6 version
```

---

## 🚀 K6 - Basic Test Script

Minimal HTTP load test example.

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

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

Run:
```bash
k6 run script.js
```

---

## 👥 K6 - Virtual Users & Duration

Control load using VUs and duration.

```bash
k6 run --vus 10 --duration 30s script.js
```

---

## 📊 K6 - Stages (Ramp Up / Down)

Simulate realistic traffic patterns.

```javascript
export const options = {
  stages: [
    { duration: '30s', target: 10 },
    { duration: '1m', target: 50 },
    { duration: '30s', target: 0 }
  ],
};
```

---

## 🎯 K6 - Thresholds (SLAs / SLOs)

Fail tests if performance criteria are breached.

```javascript
export const options = {
  thresholds: {
    http_req_duration: ['p(95)<500'],
    http_req_failed: ['rate<0.01'],
  },
};
```

---

## ✅ K6 - Checks (Assertions)

Validate responses during load.

```javascript
import { check } from 'k6';

check(res, {
  'status is 200': (r) => r.status === 200,
  'response time < 500ms': (r) => r.timings.duration < 500,
});
```

---

## 🌐 K6 - HTTP Methods

```javascript
http.get(url);
http.post(url, payload, params);
http.put(url, payload);
http.del(url);
```

---

## 🔐 K6 - Headers & Authentication

```javascript
const params = {
  headers: {
    'Authorization': 'Bearer TOKEN',
    'Content-Type': 'application/json',
  },
};
```

---

## 🔧 K6 - Environment Variables

```bash
k6 run -e BASE_URL=https://api.test.com script.js
```

```javascript
const baseUrl = __ENV.BASE_URL;
```

---

## 📝 K6 - Data Parameterization

```javascript
import data from './users.json';

export default function () {
  const user = data[Math.floor(Math.random() * data.length)];
}
```

---

## ⚙️ K6 - Executors (Advanced)

```javascript
export const options = {
  scenarios: {
    constant_load: {
      executor: 'constant-vus',
      vus: 20,
      duration: '1m',
    },
  },
};
```

---

## 💪 K6 - Stress Testing

```javascript
stages: [
  { duration: '1m', target: 50 },
  { duration: '1m', target: 200 },
  { duration: '30s', target: 0 },
]
```

---

## ⚡ K6 - Spike Testing

```javascript
stages: [
  { duration: '10s', target: 200 },
  { duration: '1m', target: 0 },
]
```

---

## ⏱️ K6 - Soak Testing

```javascript
{ duration: '2h', target: 50 }
```

---

## 📄 K6 - Output to JSON

```bash
k6 run --out json=results.json script.js
```

---

## 📊 K6 - InfluxDB Integration

```bash
k6 run --out influxdb=http://localhost:8086/k6 script.js
```

---

## 🔄 K6 - CI/CD Usage

```bash
k6 run script.js || exit 1
```

---

## 📈 K6 - Common Metrics

| Metric | Description |
|------|-------------|
| http_req_duration | Total request time |
| http_req_failed | Failed request rate |
| vus | Active virtual users |
| checks | Assertion results |

---

## 🐛 K6 - Debugging

```bash
k6 run --http-debug="full" script.js
```

---

## ✅ K6 - Best Practices Checklist

- [ ] Define clear SLAs
- [ ] Add thresholds
- [ ] Use realistic data
- [ ] Monitor backend metrics
- [ ] Fail CI on performance breach

---

────────────────────────────────────────────────────────────

Full page: https://devtools.krishanchawla.com/devtools/k6-load-testing-cheatsheet
More tools: https://devtools.krishanchawla.com