How to Perform Load Testing in NestJS with k6

Load testing is a crucial part of the development process to ensure that your NestJS application can handle real-world traffic and user loads. In this tutorial, we'll walk you through the process of performing load testing on a NestJS application using the k6 tool. k6 is a popular open-source load testing tool that's easy to use and provides powerful scripting capabilities.

Prerequisites

Before you begin, make sure you have the following prerequisites in place:

1. Node.js and npm: Ensure that you have Node.js and npm (Node Package Manager) installed on your machine.
2. NestJS Application: You should have a NestJS application that you want to load test.

Install k6

To get started, you'll need to install k6 globally on your machine. Open your terminal and run the following command:

npm install -g k6         

This command installs k6 globally so you can run it from any directory.

Create a Load Testing Script

Now it's time to create a load testing script using k6. Create a new file named loadtest.js in your project directory.

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

export let options = {
  vus: 10, // Virtual Users
  duration: '30s', // Duration of the test
};

export default function () {
  let res = http.get('https://localhost:3000/api/endpoint'); // Update with your API endpoint
  check(res, {
    'status is 200': (r) => r.status === 200,
  });
  sleep(1);
}        

In this script:

• We import the necessary functions from the k6 library.
• We define the load testing configuration using the options object. Here, we're simulating 10 virtual users (vus) for a duration of 30 seconds.
• Inside the default function, we make an HTTP GET request to your NestJS API endpoint and perform a simple status code check.
• The sleep function introduces a 1-second delay between each request to simulate a more realistic scenario.

Replace 'https://localhost:3000/api/endpoint' with the actual endpoint you want to test.

Run the Load Test

With the load testing script in place, you can now run the load test. Open your terminal and navigate to the directory containing the loadtest.js script. Run the following command:

k6 run loadtest.js         

k6 will start executing the load test script and display real-time statistics as the test progresses.

Analyze Results

Once the load test completes, k6 will provide detailed statistics about the test's performance, including response times, error rates, throughput, and more. Analyze these results to identify any bottlenecks or performance issues in your NestJS application.The results of the load test can be analyzed using the k6 dashboard. To open the k6 dashboard, you can run the following command

k6 dashboard        

Conclusion

In this tutorial, we learned how to perform load testing in NestJS with k6. We created a simple load test script and ran it against a NestJS application. We then analyzed the results of the load test using the k6 dashboard.

I hope this tutorial was helpful. For more information on k6, please visit the k6 documentation: https://k6.io/docs/.