EnvValidator

EnvValidator is a lightweight Python library that helps validate environment variables against a predefined schema. It ensures that required variables exist, follow the correct type or format, and falls back to system environment variables when an .env file is missing.

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Features

• Schema-Based Validation - Define expected environment variables and their types (string, int, bool, regex).
• Automatic Fallback - If no .env file is found, it retrieves values from system environment variables.
• Regex Support - Enforce custom formats (e.g., API keys, UUIDs).
• Error Handling - Provides clear error messages when validation fails.
• Lightweight & Fast - Minimal overhead with a simple API.

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Requirements

• Python 3.x (recommended: 3.7 or higher)

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Installation

Install the package using pip:

pip install envvalidator

Usage

Here is an example of how to use EnvValidator:

# Define the expected schema
schema = {
    "DATABASE_URL": "string",
    "DEBUG": "bool",
    "PORT": "int",
    "API_KEY": {"regex": r"^[A-Za-z0-9]{32}$"}  # Ensure 32-character API key format
}

try:
    ENV = envvalidator.validate_env(".env", schema)
    print(ENV)
except ValueError as e:
    print("Configuration error:", e)

Output Example

If .env contains:

DATABASE_URL=postgres://user:pass@localhost:5432/db
DEBUG=true
PORT=8080
API_KEY=1234567890abcdef1234567890abcdef

The output would be:

{
    "DATABASE_URL": "postgres://user:pass@localhost:5432/db",
    "DEBUG": "true",
    "PORT": "8080",
    "API_KEY": "1234567890abcdef1234567890abcdef"
}

If a required variable is missing or does not match the expected type, an error is raised.

How It Works

1. Reads the .env file (if available).
2. Parses key-value pairs and trims whitespace.
3. Checks each variable against the schema:
   • If defined in .env, it is validated.
   • If missing, it looks in system environment variables.
   • If validation fails, an error is raised.
4. Returns a dictionary of validated environment variables.

Limitations

• Does not support deeply nested configurations (e.g., JSON-like structures).
• Assumes all values are stored as strings in environment variables.

Contributing

Contributions are welcome! Feel free to open an issue or submit a pull request if you have suggestions or improvements.

Local Development

To set up a local development environment, follow these steps:

1. Create and activate a virtual environment:

   python -m venv venv
   source venv/bin/activate  # macOS/Linux
   venv\Scripts\activate     # Windows
   pip install -r requirements.txt

2. Build & install the project

   python setup.py build
   python setup.py install

3. Run an example script to test:

   python examples/example.py

The module is now installed in the virtual environment. You can test it by running the example script:

python examples/example.py

License

This project is licensed under the Apache-2.0 License. See the LICENSE file for details.

Author

Developed by Qiyaya

Acknowledgements

Thanks to the Python (and ...) development communities for providing tools and resources to make this project possible.

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