Locust installation and setup

Installation

To install Locust, follow the instructions at Locust Installation

Create a directory for the Locust project
Create a subdirectory for the source code
Create a new Anaconda virtual Python environment. ( At the time of writing Python version 3.10 is the latest. )
conda create -n locust python=3.10
Activate the new virtual environment
conda activate locust
Install Locust
pip3 install locust
Check the success of the installation
locust -V

Troubleshooting

If the check fails with the error message

ValueError: greenlet.greenlet size changed, may indicate binary incompatibility. Expected 152 from C header, got 40 from PyObject

Make sure you use the Anaconda virtual Python environment to avoid version conflicts between installed Python components.

Create your first test

See https://docs.locust.io/en/stable/quickstart.html for the Quick Start tutorial.

Create the test file
locustfile.py
Specify the actions to be taken

import time
from locust import HttpUser, task, between

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

  @task(3)
  def view_items(self):
    # self.client.get(url + "/")
    self.client.get("/")

  @task
  def hello_world(self):
    # self.client.get(url + "/about")
    self.client.get("/about")


  def on_start(self):
    a = 0 # Just a placeholder, as every def has to have at least one executable instruction
    # No login is necessary for this site
    # self.client.post("/login", json={"username":"foo", "password":"bar"})

Starting Locust

Open a terminal in the directory where the locustfile.py is located.
Start Locust with
locust -f locustfile.py
Open the web UI at http://localhost:8089/
Specify the number of concurrent users and the span rate of the users. Enter the URL of the site to be tested. IMPORTANT: Make sure there is no slash at the end of the URL, otherwise the generated URL will contain double slashes!!!
Click the Start swarming button.

Changing the load test script

To make sure, Locust will execute the updated script

Stop the Locust process in the terminal with CTRL-C
Modify and save the locustfile.py file
Start the Locust process with
locust -f locustfile.py