git commit message hook, that automatically adds ticket number to commit message

commit-msg.py

#!/usr/bin/python
#-*- coding: utf-8 -*-
import os
import re
import sys
import shutil
import subprocess


re_ticket = re.compile(ur'(?u)^([0-9]+)-.+')


def git(*args):
    p = subprocess.Popen(
        ('git',) + args,
        shell=True,
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT,
    )
    p.wait()
    return p.stdout.read()


def current_branch():
    return git('symbolic-ref', '--short', '-q', 'HEAD').strip()


def ensure_message_file_refs(filename):
    if os.path.exists(filename):
        m = re_ticket.match(current_branch())
        if m:
            ticket_nbr = '#' + m.group(1)
            with open(filename, 'rt') as fp:
                content = fp.read()
            if ticket_nbr not in content:
                content = content.rstrip() + u'\nRefs ' + ticket_nbr
                with open(filename, 'wt') as fp:
                    fp.write(content)
                print 'Succesfully appended "Refs ' + ticket_nbr + '"'
                return 0
    else:
        print 'message file not found at %r' % (filename)
        return 1


if __name__ == '__main__':
    if len(sys.argv) > 1:
        sys.exit(ensure_message_file_refs(sys.argv[1]))
    else:
        here = os.path.dirname(os.path.abspath(__file__))
        hook = os.path.join(here, '.git', 'hooks', 'commit-msg')
        shutil.copy(__file__, hook)
        print 'Succesfully installed commit-msg hook'