Load Testing with HTTP POST Requests in Locust

Understanding HTTP POST in Load Testing

POST requests are used to send data to a server to create or update a resource. They are typically employed in scenarios like:

• Submitting forms

• Uploading files

• Sending data to APIs for storage or processing

For load testing, simulating POST requests helps evaluate how well an application handles concurrent writes and ensures data integrity under high loads.

Example: Performing POST Requests with Locust

Below is an example of a Locust HttpUser class that performs both GET and POST requests

from locust import HttpUser, constant, task
import uuid


class MyReqRes(HttpUser):

    wait_time = constant(1)  # Wait 1 second between tasks
    host = "http://localhost:8001"  # Base URL for the API

    @task
    def get_todos(self):
        # GET request to retrieve a specific todo item
        res = self.client.get("/todos/104")
        print(res.text)

    @task
    def create_todos(self):
        # Generate a unique ID and create a todo item
        request = {
            "id": str(uuid.uuid4()),
            "name": "Meet at 9 AM",
            "description": "Need to meet client at 9 AM tomorrow"
        }
        # POST request to create a new todo
        res = self.client.post("/todos", json=request)
        print(res.text)

Explanation of the Code

1. MyReqRes Class

This class defines the user behavior, combining both GET and POST requests.

• HttpUser Base Class: Provides built-in methods like get and post for HTTP requests.

• wait_time: The constant(1) function ensures the user waits 1 second between tasks.

• host: Sets the base URL for the API.

2. create_todos Task

This task simulates creating a new "todo" item:

• Dynamic Data with uuid: A unique ID is generated for each request using Python’s uuid module.

• Payload (request): Contains data to be sent to the server, including an ID, name, and description.

• POST Request: The self.client.post method sends the payload as JSON to the /todos endpoint.

3. get_todos Task

This task retrieves an existing "todo" item to validate the GET functionality.