Update your default branch in GitHub (default: main)

update_github_default_branch.py

"""Update your default branch in GitHub (default: main).

This script will rename the master branch (default: main), push the new branch to GitHub,
optionally delete the master branch (default: True, delete master).

python update_github_default_branch.py

Installation
------------

pip install GitPython PyGitHub

# Create a Github Token: https://github.com/settings/tokens/

export GITHUB_API_KEY=<token>

cd <into a clone of the repo to update>

This assumes your remote is named "origin" and you are currently on the 'master'
branch.
"""
import os

import git
import github

from git import InvalidGitRepositoryError

def main(argv=None):
    api_key = os.environ.get('GITHUB_API_KEY')

    try:
        repo = git.Repo('.')
    except InvalidGitRepositoryError as err:
        print(f'Please change to the root repo directory. Currently at: {err}')
        return 0

    try:
        assert repo.active_branch.name == 'master'
    except AssertionError:
        print('Please change to the master branch of this repo.')
        #return 0

    repo.active_branch.rename(argv.branch)
    remote = repo.remote()
    remote.push('main')

    remote_url = list(remote.urls)[0]
    if remote_url.startswith('https'):
        repo_name = '/'.join(remote_url.split('.')[1].split('/')[1:])
    elif remote_url.startswith('git'):
        repo_name = remote_url.split('.')[1].split(':')[1]
    else:
        print('Remote URL protocol unknown: {remot_url}')
        return 0

    try:
        print(f'Setting default branch for: {repo_name}')
        g = github.Github(api_key)
        gh_repo = g.get_repo(repo_name)
    except UnknownObjectException:
        print('Please ensure that your API key has permissions to manage this repo.')
        return 0

    gh_repo.edit(default_branch=argv.branch)

    if argv.delete_master:
        gh_repo.get_git_ref('heads/master').delete()

if __name__ == '__main__':
    import sys
    import argparse
    parser = argparse.ArgumentParser(prog='update_github_default_branch.py',
                                     description='Update your default branch in GitHub.',
                                     formatter_class=argparse.RawDescriptionHelpFormatter,
                                     epilog=__doc__)
    parser.add_argument('-b --branch',
                        dest='branch',
                        type=str,
                        default='main',
                        help="Set the name of the default branch in Github.")
    parser.add_argument('-d --delete-master',
                        dest='delete_master',
                        type=bool,
                        default=True,
                        help="Delete the master branch.")
    args = parser.parse_args()
    sys.exit(main(argv=args))