set version in python package in a github action using GITHUB_REF

set-python-version.py

#!/usr/bin/env python3
"""
see https://gist.github.com/samuelcolvin/da2f521da5d2195fbfd65da3b8f58589 for details
"""
import os
import re
import sys
from pathlib import Path


def main(version_path_env_var='VERSION_PATH', version_env_vars=('VERSION', 'GITHUB_REF')) -> int:
    version_path = os.getenv(version_path_env_var)
    if not version_path:
        print(f'✖ "{version_path_env_var}" env variable not found')
        return 1
    version_path = Path(version_path)
    if not version_path.parent.is_dir():
        print(f'✖ path "{version_path.parent}" does not exist')
        return 1

    version = None
    for var in version_env_vars:
        version_ref = os.getenv(var)
        if version_ref:
            version = re.sub('^refs/tags/v*', '', version_ref.lower())
            break
    if not version:
        print(f'✖ "{version_env_vars}" env variables not found')
        return 1

    print(f'writing version "{version}", to {version_path}')
    version_path.write_text(f"""\
__all__ = ('VERSION',)

VERSION = '{version}'
""")
    return 0


if __name__ == '__main__':
    sys.exit(main())

usage.md

To use simply run

VERSION_PATH='<your package dir>/version.py' python <(curl -Ls https://git.io/JT3rm)