Richard Burke The Doors of Perception

Introduction to Locust

Locust is an open-source load testing tool that allows you to define user behavior and test the performance of your system under varying levels of load. Unlike traditional load testing tools, Locust uses Python for scripting, making it highly flexible and easy to extend. This tutorial will walk you through the steps to set up and run a basic load test using Locust.

Step 1: Installation

To get started with Locust, you need to install it on your machine. The simplest way to do this is via pip, Python’s package installer. Open your terminal and run the following command:

pip install locust

This will install Locust and its dependencies, allowing you to start scripting your load tests.

Step 2: Writing Your First Test

Locust tests are written in Python, which allows you to define user behavior in a highly readable and maintainable way. Create a new Python file, for example, locustfile.py, and add the following code:

from locust import HttpUser, task, between

class MyUser(HttpUser):
wait_time = between(1, 5)

@task
def my_task(self):
self.client.get("/")


This script creates a user class that performs a GET request to the root URL of your target system. The wait_time attribute defines the time each user will wait between executing tasks.

Step 3: Running the Test

With your test script ready, you can now run Locust to start the load test. Navigate to the directory containing your locustfile.py and run the following command:

locust -f locustfile.py

This will start a web interface where you can configure the number of users and the spawn rate. Open a web browser and navigate to http://localhost:8089. Enter the desired number of users and spawn rate, then click the ‘Start Swarming’ button to begin the test.

Conclusion

Locust provides a powerful and flexible way to perform load testing on your systems. By following this step-by-step tutorial, you should now have a basic understanding of how to set up and run a load test using Locust. With its ease of use and powerful features, Locust is an excellent choice for developers and testers looking to ensure their systems can handle varying levels of traffic.