Service: Locust

Locust

Locust is an open source load testing tool written in Python. You define user behaviour in plain Python code and Locust can simulate millions of simultaneous users to stress-test your web application or API. It includes a real-time web UI to monitor requests per second, response times, and failure rates while a test is running.

Getting Started

Launch a Locust instance from the OSC dashboard.

Prerequisites

• An OSC account. Sign up here.
• A locustfile.py hosted at a publicly accessible URL (e.g. a raw GitHub URL). This file defines the load test scenarios.

Write a Locust File

Create a locustfile.py that describes your test scenario:

from locust import HttpUser, task, between

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

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

    @task(3)
    def about(self):
        self.client.get("/about")

Push this file to a public GitHub repository and copy the raw URL (e.g. https://raw.githubusercontent.com/myorg/myrepo/main/locustfile.py).

Create a Locust Instance

Using the OSC dashboard

1. Go to Locust on OSC.
2. Click Create instance.
3. Fill in:
   • Name — alphanumeric identifier for the instance
   • LocustfileUrl — raw URL to your locustfile.py
4. Click Create.

Using the CLI

osc create locustio-locust myloadtest \
  -o LocustfileUrl="https://raw.githubusercontent.com/myorg/myrepo/main/locustfile.py"

Running a Test

1. Open the instance URL in your browser. The Locust web UI appears.
2. Enter the Host (base URL of the system under test, e.g. https://api.example.com).
3. Set the Number of users and Spawn rate.
4. Click Start swarming.
5. Monitor requests/sec, response times, and failures in real time on the Charts and Statistics tabs.
6. Click Stop when the test is complete.

Resources

• Locust official website
• Locust GitHub repository
• Locust documentation