How to Use HTTP Requests in Locust

Using HTTP requests in Locust is very straightforward, as Locust is primarily designed for load testing and performance testing, with built-in support for HTTP requests. With Locust’s HttpUser class, you can easily send GET, POST, and other types of HTTP requests, and leverage Locust’s powerful features to simulate the behavior of a large number of concurrent users.

Basic Steps

1. Install Locust

First, ensure that you have Locust installed. If you haven’t installed it yet, you can do so via pip:

pip install locust

2. Write a Locust Script

Here is a simple example demonstrating how to write a Locust script to perform HTTP requests.

Example Script: locustfile.py

from locust import HttpUser, task, between

class WebsiteUser(HttpUser):
    wait_time = between(1, 5)  # Wait between 1 to 5 seconds between tasks

    @task
    def index_page(self):
        """Access the homepage"""
        self.client.get("/")

    @task
    def get_posts(self):
        """Get the list of posts"""
        self.client.get("/posts")

    @task
    def create_post(self):
        """Create a new post"""
        post_data = {
            "title": "foo",
            "body": "bar",
            "userId": 1,
        }
        headers = {'Content-Type': 'application/json'}
        self.client.post("/posts", json=post_data, headers=headers)

In this example, we define a class named WebsiteUser that inherits from HttpUser. This class contains three task methods, each representing a type of HTTP request (GET or POST).

The index_page() method sends a GET request to the root path.

The get_posts() method sends a GET request to the /posts path.

The create_post() method sends a POST request to the /posts path, along with some JSON formatted data.

3. Start Locust

After saving the above code as locustfile.py, navigate to the directory containing this file in the command line and run the following command to start Locust:

locust -f locustfile.py

By default, Locust listens on http://localhost:8089. Open your browser and visit this address to see the Locust web interface.

4. Set Parameters in the Locust Web Interface

In the Locust web interface, you can set the number of users to simulate and the hatch rate (the rate at which users are started per second). Once set, click the “Start swarming” button to begin testing.

Advanced Usage

In addition to basic GET and POST requests, Locust also supports other HTTP methods such as PUT and DELETE. Furthermore, you can utilize other features provided by the client object to enhance your test scripts.

Using Headers

If you need to add specific headers to your requests, you can specify them using the headers parameter when calling client.get() or client.post():

self.client.get(“/path”, headers={“Authorization”: “Bearer your_token”})

Using Cookies

If you want to use cookies, you can add them directly in the request:

self.client.get(“/path”, cookies={“session_id”: “your_session_id”})

Or set global cookies when initializing the HttpUser instance:

def on_start(self):

self.client.cookies.set(“session_id”, “your_session_id”)

Handling Responses

You can check the response status code or content to determine subsequent actions:

with self.client.get(“/path”, catch_response=True) as response:

if response.status_code == 200:

response.success()

else:

response.failure(“Failed with status code: {}”.format(response.status_code))

This concludes the basic guide and some advanced tips for using HTTP requests in Locust. I hope this information helps you build effective performance testing scripts! If you have any further questions, feel free to ask.

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