Load Testing
k6 (recommended)
// load-test.js
import http from 'k6/http';
import { check, sleep } from 'k6';
export const options = {
stages: [
{ duration: '1m', target: 50 }, // Ramp up to 50 users
{ duration: '3m', target: 50 }, // Stay at 50
{ duration: '1m', target: 100 }, // Ramp to 100
{ duration: '3m', target: 100 }, // Stay at 100
{ duration: '1m', target: 0 }, // Ramp down
],
thresholds: {
http_req_duration: ['p(95)<500', 'p(99)<1000'], // 95th < 500ms
http_req_failed: ['rate<0.01'], // <1% error rate
},
};
export default function () {
const res = http.get('https://api.example.com/products');
check(res, {
'status is 200': (r) => r.status === 200,
'response time < 500ms': (r) => r.timings.duration < 500,
});
sleep(1);
}
Authenticated Requests
import http from 'k6/http';
export function setup() {
const res = http.post('https://api.example.com/auth/login', JSON.stringify({
email: 'loadtest@example.com', password: 'test-password',
}), { headers: { 'Content-Type': 'application/json' } });
return { token: res.json('token') };
}
export default function (data) {
const headers = { Authorization: `Bearer ${data.token}`, 'Content-Type': 'application/json' };
// Simulate user journey
http.get('https://api.example.com/products', { headers });
sleep(2);
http.get('https://api.example.com/products/1', { headers });
sleep(1);
http.post('https://api.example.com/orders', JSON.stringify({ productId: '1', qty: 2 }), { headers });
}
Artillery
# artillery.yml
config:
target: "https://api.example.com"
phases:
- duration: 60
arrivalRate: 10
name: "Warm up"
- duration: 120
arrivalRate: 50
name: "Sustained load"
defaults:
headers:
Content-Type: "application/json"
scenarios:
- name: "Browse and purchase"
flow:
- get:
url: "/products"
capture:
- json: "$.data[0].id"
as: "productId"
- think: 2
- get:
url: "/products/{{ productId }}"
- think: 1
- post:
url: "/orders"
json:
productId: "{{ productId }}"
quantity: 1
Locust (Python)
from locust import HttpUser, task, between
class WebUser(HttpUser):
wait_time = between(1, 3)
def on_start(self):
res = self.client.post("/auth/login", json={
"email": "test@example.com", "password": "password"
})
self.token = res.json()["token"]
self.headers = {"Authorization": f"Bearer {self.token}"}
@task(3)
def browse_products(self):
self.client.get("/products", headers=self.headers)
@task(1)
def create_order(self):
self.client.post("/orders", json={"productId": "1", "qty": 1}, headers=self.headers)
Test Types
| Type | Purpose | Duration |
|---|
| Smoke | Verify system works under minimal load | 1-2 min |
| Load | Expected normal/peak traffic | 10-30 min |
| Stress | Beyond normal capacity, find breaking point | 10-20 min |
| Soak | Sustained load to find memory leaks | 1-4 hours |
| Spike | Sudden traffic burst | 5-10 min |
Anti-Patterns
| Anti-Pattern | Fix |
|---|
| Testing from same network as server | Test from external network or cloud |
| No think time between requests | Add realistic sleep/think delays |
| Single endpoint only | Test realistic user journeys |
| No thresholds defined | Set p95/p99 latency and error rate thresholds |
| Running load tests against production | Use staging environment |
Production Checklist
- Realistic user scenarios (not just single endpoints)
- Thresholds for latency (p95, p99) and error rate
- Ramp-up pattern matching expected traffic shape
- Test data seeded (not reusing same record)
- CI/CD integration for regression detection
- Results archived for comparison over time
