Performance testing is a crucial part of ensuring the stability and scalability of web applications. k6 is a modern, open-source load testing tool that allows developers and testers to script and execute performance tests efficiently. In this blog, we’ll explore the basics of k6 and write a simple test script to get started.

What is k6?

k6 is a load testing tool designed for developers. It is written in Go but uses JavaScript for scripting tests. Key features include,

• High performance with minimal resource consumption
• JavaScript-based scripting
• CLI-based execution with detailed reporting
• Integration with monitoring tools like Grafana and Prometheus

Installation

For installation check : https://grafana.com/docs/k6/latest/set-up/install-k6/

Writing a Basic k6 Test

A k6 test is written in JavaScript. Here’s a simple script to test an API endpoint,

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

export let options = {
  vus: 10, // Number of virtual users
  duration: '10s', // Test duration
};

export default function () {
  let res = http.get('https://api.restful-api.dev/objects');
  check(res, {
    'is status 200': (r) => r.status === 200,
  });
  sleep(1); // Simulate user wait time
}

Running the Test

Save the script as script.js and execute the test using the following command,

k6 run script.js

Understanding the Output

After running the test, k6 will provide a summary including

1. HTTP requests: Total number of requests made during the test.

2. Response time metrics:

• min: The shortest response time recorded.

• max: The longest response time recorded.

• avg: The average response time of all requests.

• p(90), p(95), p(99): Percentile values indicating response time distribution.

3. Checks: Number of checks passed or failed, such as status code validation.

4. Virtual users (VUs):

• vus_max: The maximum number of virtual users active at any time.

• vus: The current number of active virtual users.

5. Request Rate (RPS – Requests Per Second): The number of requests handled per second.

6. Failures: Number of errors or failed requests due to timeouts or HTTP status codes other than expected.

Next Steps

Once you’ve successfully run your first k6 test, you can explore,

• Load testing different APIs and endpoints
• Running distributed tests
• Exporting results to Grafana
• Integrating k6 with CI/CD pipelines

k6 is a powerful tool that helps developers and QA engineers ensure their applications perform under load. Stay tuned for more in-depth tutorials on advanced k6 features!