README.md

argparsenv

This project extends python's argparse module to allow for environment variable overrides of command line arguments.

The rule for environment variable overrides is as follows:

1. If the argument is provided on the command line, the environment variable is ignored.
2. If the argument is not provided on the command line, the environment variable is used if it is set.
3. If the argument is not provided on the command line and the environment variable is not set, the default value is used.
4. If the argument is environment variable is set both on the command line and in the environment, the command line value is used.

Installation

Stable release version:

pip install argparsenv

Latest development version:

pip install git+https://github.com/snaeil/argparsenv

Usage

This module builds on top of python's standard library argparse.

import argparsenv

env_arg_parser = ArgumentParser()
env_arg_parser.add_argument(
    "--port",
    dest="port",
    env_var="MY_APP_DB_PORT",
    default="3306",
)

With this ArgumentParser instance, the port argument can be set in three ways:

1. On the command line:

python my_app.py --port 3307

2. As an environment variable (this can also be done by using a .env file):

export MY_APP_DB_PORT=3307
python my_app.py

3. Using the default value (here 3306):

python my_app.py

Contributing

Contributions are welcome! For feature requests, bug reports or questions, please open an issue. For code contributions, please open a pull request.

Please make sure to install pre-commit before making changes to the code (this enables checks for code formatting, linting, etc. before committing changes):

pip install poetry
poetry install
cd path/to/argparsenv
pre-commit install