k6-spike-test-demo.js

import http from 'k6/http';
import { check, sleep } from 'k6';
import { Rate } from 'k6/metrics';
import { htmlReport } from "https://raw.githubusercontent.com/benc-uk/k6-reporter/main/dist/bundle.js";
import { textSummary } from "https://jslib.k6.io/k6-summary/0.0.1/index.js";

// Custom metric to track failure rate (for our checks)
const failureRate = new Rate('check_failure_rate');

/*
  Spike test example:
  - Keep a small baseline of virtual users for a period
  - Suddenly spike to a very large number of users for a short time
  - Return quickly back to baseline and observe recovery

  This demonstrates how the system behaves under a sudden surge of traffic.
*/
export const options = {
  stages: [
    // Baseline warm-up
    { duration: '10s', target: 10 },     // Ramp up to 10 users
    { duration: '30s', target: 10 },      // Steady baseline for 30 seconds

    // Spike
    { duration: '5s', target: 500 },    // Rapid ramp up to 500 users (spike)
    { duration: '30s', target: 500 },     // Stay at spike load for 30 seconds

    // Recovery back to baseline
    { duration: '20s', target: 10 },     // Rapid ramp down to baseline
    { duration: '30s', target: 10 },      // Let the system recover at baseline

    // Cooldown to 0
    { duration: '30s', target: 0 },      // Ramp down to 0 users
  ],

  // Thresholds tuned for spike (we allow some degradation during spike but keep limits reasonable)
  thresholds: {
    'http_req_duration': [
      'p(95)<2000',  // 95% of requests should be below 2s
      'p(99)<5000',  // 99% of requests should be below 5s during a big spike
    ],
    'http_req_failed': ['rate<0.10'],      // Allow up to 10% failure rate during the spike
    'check_failure_rate': ['rate<0.10'],   // Same threshold for our custom check
  },
};

export default function () {
  // Target URL - adjust if your API runs on a different host/port
  const url = 'http://localhost:5127/mostborrowedbook';

  // Add a tag so metrics in k6 can be filtered/grouped by endpoint
  const response = http.get(url, { tags: { name: 'MostBorrowedBook' } });

  // Basic checks to validate correctness and a soft latency guard
  const checks = check(response, {
    'status is 200': (r) => r.status === 200,
    'response time < 2000ms': (r) => r.timings.duration < 2000,
    'valid response body': (r) => r.body && r.body.length > 0,
  });

  // Record custom metric for later assertions
  failureRate.add(!checks);

  // Helpful debug log when things fail — keep minimal to avoid log spam during large spikes
  if (!checks) {
    console.log(`Check failed. status=${response.status} duration=${response.timings.duration}`);
  }

  // Short randomized sleep to avoid perfectly synchronized requests
  sleep(Math.random() * 1 + 0.5); // 0.5 - 1.5s
}

// Produce an HTML report plus a console summary when the test finishes
export function handleSummary(data) {
  return {
    "spike-test-results.html": htmlReport(data),
    stdout: textSummary(data, { indent: ' ', enableColors: true }),
  };
}