Git hook to automatically tag new versions

post-commit

#!/usr/bin/env python3
# -*- coding: UTF-8 -*-

"""
This git hooks makes sure a tag is created each time the version is increased.
This version only works with version from `setup.py` and `settings.gradle`, but can be adapted.
To enable it on git 2.9+, use::
	chmod u+x dev/hooks/*
	git config core.hooksPath dev/hooks
On older versions, copy or symlink the hooks to `.git/hooks`
https://gist.github.com/mverleg/9988b44d57b63b0eef40dd9ce7b48e45
"""

from re import findall
from sys import stderr
from subprocess import Popen, PIPE
from os.path import exists


def git(cmd):
	"""
	Run a git command and return the output.
	"""
	out, err = Popen('git {0:s}'.format(cmd), shell=True, stdout=PIPE, stderr=PIPE).communicate()
	assert not err.strip()
	return out.decode('utf-8')


def get_existing_versions():
	"""
	Get all versions for which there is a tag.
	"""
	return set(tag.strip().lstrip('v') for tag in
			git('tag --list --format "%(refname:short)"').splitlines())


def get_setup_py_version():
	if exists('setup.py'):
		with open('setup.py', 'r') as fh:
			res = findall(r'\n[^#\n]*version\s*=[\'"]([\w.-_]+)[\'"]', fh.read())
		assert len(res) != 0, 'Did not find version inside setup.py'
		assert len(res) < 2, 'Found multiple versions inside setup.py'
		return res[0].strip().lstrip('v')
	return None


def get_settings_gradle_version():
	if exists('settings.gradle'):
		with open('settings.gradle', 'r') as fh:
			""" Only single-quotes supported, because double quotes may contain variables. """
			res = findall(r'\n\s*version\s*=\s*\'([\w.-_]+)\'', fh.read())
		assert len(res) != 0, 'Did not find version inside settings.gradle'
		assert len(res) < 2, 'Found multiple versions inside settings.gradle'
		return res[0].strip().lstrip('v')
	return None


def get_current_version():
	"""
	Get the current version of the project, according to package file.
	PWD is the root of the git project.
	"""
	return get_setup_py_version() or get_settings_gradle_version() or None


def version_tag():
	"""
	Create a tag for the current version if there isn't one yet.
	"""
	version = get_current_version()
	if version is None:
		""" No version found. """
		return
	versions = get_existing_versions()
	if version in versions:
		""" Version already tagged. """
		return
	print('CREATING TAG {0:} (use `git tag --delete {0:}` if not desired)'.format(version))
	git('tag v{0:}'.format(version))


try:
	exit(version_tag())
except Exception as err:
	stderr.write(err)
exit(1)

Used in json-tricks and Mango