Git commit-msg hook written in Python to validate that branch names and commit messages include matching references to their corresponding issue.

commit-msg

#!/usr/bin/python3

import sys
import re
import subprocess


PROJECT_IDS = ['SLO']
BRANCH_TYPES = ['feature', 'bug', 'hot']

REGEX_PROJECT_IDS = '|'.join(PROJECT_IDS)
REGEX_BRANCH_TYPES = '|'.join(BRANCH_TYPES)

# Should contain a capturing group to extract the reference:
REGEX_BRANCH = '^(?:{})/((?:{})-[\d]{{1,5}})-[a-z]+(?:-[a-z]+)*$'.format(REGEX_BRANCH_TYPES, REGEX_PROJECT_IDS)

# Should contain a capturing group to extract the reference (note the dot at the end
# is optional as this script will add it automatically for us):
REGEX_MESSAGE = '^((?:{})-[\d]{{1,5}}): .+\.?$'.format(REGEX_PROJECT_IDS)

# No capturing group. Just checking for the bare minimum:
REGEX_BASIC_MESSAGE = '^.+$'

# These branch names are not validated with this same rules (permissions should be configured
# on the server if you want to prevent pushing to any of these):
BRANCH_EXCEPTIONS = ['development', 'develop', 'dev', 'staging', 'sta', 'master', 'production']


def getBranchName():
  return subprocess.check_output(['git', 'rev-parse', '--abbrev-ref', 'HEAD']).decode('ascii').strip()

def getBranchRef(branch):
    match = re.findall(REGEX_BRANCH, branch)

    return match[0] if match and match[0] else None

def getMessageRef(message):
    match = re.findall(REGEX_MESSAGE, message)

    return match[0] if match and match[0] else None

def isCommitValid(message):
    isValid = True
    messageOverride = None
    branch = getBranchName()
    isException = branch in BRANCH_EXCEPTIONS

    if isException:
        print('\nWARNING: You might not have permissions to push to `{}`.'.format(branch))

        if not message.startswith('HOT: '):
            print('\n         Also, you might consider prefixing the commit message with `HOT:`')

        print('\n         Use `git reset HEAD~` to undo this commit, create a proper branch and/or commit message and commit the changes again.')
        print('')

        return True

    branchRef = getBranchRef(branch)
    messageRef = getMessageRef(message)

    if not re.match(REGEX_BRANCH, branch):
        isValid = False
        print('\nERROR: Invalid branch name:')
        print('\n       It should match {}'.format(REGEX_BRANCH))
        print('\n       Example: {}/{}-42-whatever-this-is'.format(
            BRANCH_TYPES[0],
            PROJECT_IDS[0]
        ))

    if not re.match(REGEX_MESSAGE, message):
        if not re.match(REGEX_BASIC_MESSAGE, message):
            # So wrong there's no way to fix it automatically:
            isValid = False
            print('\nERROR: Super invalid commit message (shame on you):')
            print('\n       It should match `{}`'.format(REGEX_MESSAGE))
            print('\n       Example: {}: Your commit message (with a dot at the end).'.format(
                branchRef if branchRef else '{}-42'.format(PROJECT_IDS[0])
            ))
        else:
            # Let's make a guess about the branch type and reference:
            messageOverride = 'feature/{}: {}'.format(branchRef, message)

            if not messageOverride.strip().endswith('.'):
                # The dot might be present in the original (but mostly incorrect) message:
                 messageOverride = messageOverride.strip() + '.\n'

            print('\nWARNING: Mostly invalid commit message:')
            print('\n         It should match `{}`'.format(REGEX_MESSAGE))
            print('\n         We have tried to fix it for you (no need to thank us):')
            print('\n         {}'.format(messageOverride))
            print('         Use `git reset HEAD~` to undo this commit if we fucked up.')
    elif isValid and not message.strip().endswith('.'):
        # The dot is optional, so both branch & message might be valid and still miss it:
        messageOverride = message.strip() + '.\n'

        print('\nWARNING: You forgot the dot at the end of your commit message:')
        print('\n         We have added it for you (you are welcome):')
        print('         {}'.format(messageOverride))

    if not messageOverride and isValid and branchRef != messageRef:
        isValid = False
        print('\nERROR: Branch ({}) and commit ({}) references do not match.'.format(
            branchRef,
            messageRef
        ))

    if not isValid or messageOverride:
        print('')

    return (isValid, messageOverride)


def main():
    messageFile = sys.argv[1]

    try:
        file = open(messageFile, 'r')
        message = file.read()
    finally:
        file.close()

    isValid, messageOverride = isCommitValid(message)

    if messageOverride:
        try:
            file = open(messageFile, 'w')
            message = file.write(messageOverride)
        except:
            isValid = False
        finally:
            file.close()

    sys.exit(0 if isValid else 1)


if __name__ == "__main__":
    main()

You can also check it out here in case I forget to update this one at some point: https://github.com/Danziger/dotfiles/blob/master/githooks/commit-msg