git commit-msg hook to reject bad formated messages

commit-msg

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import sys
import re

def checkMessage(msg):
  """
  Checks if the message content matches one of the message rules
  B: <message>
  R: <message>
  F: <message>
  S: <message>
  Merge
  Added tag v\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3} for changeset \.{12}
  """
  message_pattern = re.compile(
    "^((B|F|S|R)(:\s)(.)*)|"
    "^(Merge)$|"
    "^(Added tag v\d{1,3}\.\d{1,3}\.\d{1,5}\.\d{1,5} for changeset .{12})$|"
    "^(Removed tag v\d{1,3}\.\d{1,3}\.\d{1,5}\.\d{1,5})$",
    re.IGNORECASE)
  if message_pattern.match(msg):
    return False
  return True

def printUsage(msg, lineNumber):
  """
  Print all allowed message formats
  Added tag v1.4.3.6 for changeset 91ed85071cd4
  Removed tag v1.4.3.6
  """
  valid_messages = {'B: <message>': 'Bug', 'F: <message>': 'Feature',
                    'R: <message>': 'Refactoring',
                    'S: <message>': 'Specification'}

  out = 'Your commit message: %s in line %d is not valid \n' \
        'the following message formats are allowed\n\n' % (msg, lineNumber + 1)
  out += '{0:20}    {1:20}\n'.format('Message Format', 'Description')

  for msg, desc in valid_messages.items():
    out += '{0:20} =  {1:20}\n'.format(msg, desc)

  out += '{0:20} =  {1:20}\n'.format('Merge', 'Merge')
  print(out + '\n')
  return


def main():
    lines = []

    with open(sys.argv[1], 'r') as msgfile:
        lines = msgfile.readlines()

    for i, line in enumerate(lines):
        invalid = checkMessage(line)
        if invalid:
            printUsage(line, i)
            sys.exit(1)
    sys.exit(0)


if __name__ == '__main__':
    main()

Git commit-msg hook

What is this script about?

This script checks every commit message before you commit your changes. The pattern that I use on commit messages looks like this

• B: for a Bug
• F: for a Feature
• R: for Refactoring
• S: for a Specification
• and Merge for Merges

Setup global git hook

Unfortunately it's not as easy as on mercurial but here we go.

1. you have to setup a custom template directory for git
   make a directory where you like to have it, I placed mine under my home folder
   ~\.git_template\hooks\ on windows
   ~/.git_template/hooks/ on unix based
   now let's tell git to take this folder as template folder by running the following command in a shell
   git config --global init.templatedir ~\.git_template on windows
   git config --global init.templatedir ~/.git_template on unix based
2. place the script 'commit-msg' in the ~\.git_template\hooks\ folder
   on Unix based systems use ~/.git_template/hooks/
3. init a new or reinit a old git repository by putting git init to your shell at your target location
4. there is no 4. point!

Possible fault

• do not add a file extension to the file
• make sure the file is executable on unix based systems chmod a+x [commit-msg]
• if you get a env: python\r: No such file or directory on Unix based systems you have to run dos2unix on the script file