🚀 API Performance Testing using Locust

This project sets up API performance testing using Locust—a scalable, open-source load testing tool that lets you simulate thousands of concurrent users to test the performance of your API endpoints.

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📌 What Is Locust?

Locust is a modern load testing tool that allows you to write test scenarios in Python. It's developer-friendly, supports real-time web UI monitoring, and integrates easily with CI/CD pipelines.

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🧪 What You Can Test

• Concurrent user load on REST APIs
• Response time under load
• RPS (Requests Per Second) benchmarking
• Performance regressions
• Load limits and bottlenecks
• Apply Custom Load shapes

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Install Dependencies

pip install -r requirements.txt

1. Create Virtual Environment

1. Go to project directory and Create a virtual environment using python -m venv venv
2. Type venv\Scripts\activate.bat and hit enter
3. Create a requirements.txt file and add the required library. For Ex: To install locust, add locust==2.24.0 in the file. (This i have added alerady)
4. Run the command to install the library. pip install -r requirements.txt.
5. Run the application locust -f getorder.py

2. Launch Locust Web UI:

locust -f locustfile.py --host=http://localhost:8000

3. Open browser and navigate to:

http://localhost:8089

Enter load parameters:

Number of users (e.g., 100) Spawn rate (e.g., 10 users/sec) Click Start Swarming

📈 Using Custom Load Shape For more control over traffic patterns (e.g., ramp-up, plateau, ramp-down), use a custom load shape defined in customshapes/collectionlist-bellcurve.py

✅ Run with Custom Load Shape locust -f locustfile.py load_shape.py --host=http://localhost:8000

🛠️ Headless Mode (CI/CD) locust -f locustfile.py --host=http://localhost:8000 --headless -u 100 -r 10 -t 2m

📊 Metrics Observed Requests per second (RPS)

Average and percentile response times (p50, p95)

Failure rates

Active users and throughput over time