🐍 How to Structure Your Python Projects for AWS Lambda, APIs, and CLI Tools

✅ Beginner-friendly | 🔥 Hands-on Guide | 🧩 File Structure Examples

When you start working on Python projects—whether for AWS Lambda, building an API, or creating a CLI tool—it’s important to organize your code in a clean and simple way.

A well-structured project is easy to maintain, scale, and share with others.

In this post, I will show common file and folder structures I personally use in my projects. These structures are helpful for newcomers, junior devs, or even freelancers who want to start clean from the beginning.

🐍 1. Python Project for AWS Lambda (Multiple Files)

When working with AWS Lambda, you often split your code into reusable files. This makes your handler clean and easier to manage.

📁 Folder Structure:

your-lambda-project/
├── src/
│   ├── lambda_function.py       # Main Lambda handler
│   ├── config.py                # Environment or API config
│   ├── logger.py                # Custom logger setup
│   ├── utils.py                 # Helper functions
│   ├── services.py              # AWS or API calls
│   ├── validator.py             # Input validations
│   ├── exceptions.py            # Custom error handling
│   ├── constants.py             # Static values
│   └── integration.py           # API/database integration logic
├── requirements.txt             # Dependencies
├── serverless.yml               # Serverless Framework (optional)
├── Dockerfile                   # If you deploy using containers
├── README.md
└── CHANGELOG.md

🐍 2. Python Project for API (Flask or FastAPI)

Building RESTful APIs with Flask or FastAPI? You can group files like this for better readability and code separation.

📁 Folder Structure:

your-api-project/
├── src/
│   ├── main.py                  # Entry point to run the app
│   ├── routes.py                # API routes/endpoints
│   ├── controllers.py           # Logic for each route
│   ├── services.py              # Handle DB/API calls
│   ├── models.py                # Pydantic or DB models
│   ├── config.py
│   ├── logger.py
│   ├── utils.py
│   ├── exceptions.py
│   └── constants.py
├── requirements.txt
├── .env                         # Environment variables
├── Dockerfile                   # Container support (optional)
├── README.md
└── CHANGELOG.md

🐍 3. Python CLI Tool Project

Python is also great for building command-line tools. You can use argparse or click to handle user inputs.

📁 Folder Structure:

your-cli-tool/
├── src/
│   ├── main.py                  # CLI entry script
│   ├── cli.py                   # Argument parsing or click commands
│   ├── commands.py              # CLI command logic
│   ├── utils.py
│   ├── logger.py
│   ├── config.py
│   ├── constants.py
│   └── exceptions.py
├── setup.py                     # For making your CLI installable
├── requirements.txt
├── Dockerfile                   # Optional for packaging
├── README.md
└── CHANGELOG.md

🛠️ Tips for Beginners

  • ✅ Use src/ folder to keep your Python code separate.
  • ✅ Keep your requirements.txt updated.
  • ✅ Always add README.md to explain how your code works.
  • ✅ Group similar logic into their own files (e.g., services, utils).
  • ✅ Add Dockerfile only if needed (for deployment or testing).
  • ✅ If you use Serverless Framework, include serverless.yml.

✨ Final Thoughts

Whether you are a beginner, a junior dev, or a self-learner like me—starting with the right folder structure helps you write better code, collaborate easier, and debug faster.

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