Prepend commit message with ticket number from branch name

prepare-commit-msg

#!/usr/bin/env python3

# https://gist.github.com/kevindb/a360c8e90bcdf6364f1523a5787c8d89

import sys, re
from subprocess import check_output

commit_msg_filepath = sys.argv[1]

branch = check_output(['git', 'branch', '--show-current']).decode('utf-8').strip()

# Branch name is empty if in detached HEAD state (e.g. rebase)
if len(branch) > 0:
    # Regex breakdown:
    #   ^                                   # Start of string
    #   (?:(feature|hotfix|bugfix|epic)/)?  # Optional group for prefix and slash
    #   (\w+-\d+)                           # JIRA-style issue key (e.g. ENG-1000)
    regex = r'^(?:(feature|hotfix|bugfix|epic)/)?(\w+-\d+)'

    match = re.match(regex, branch)
    if match:
        issue = match.group(2)
        with open(commit_msg_filepath, 'r+') as fh:
            commit_msg = fh.read()
            fh.seek(0, 0)
            fh.write(f"[{issue}] {commit_msg}")
    else:
        print("Incorrect branch name.")
        print("Please use the format <feature|epic|hotfix|bugfix>/<ticket number> [-additional-description] or <ticket number>")
        print("e.g. 'feature/ENG-1000', 'hotfix/ENG-2500-this-is-the-fix', or just 'ENG-1000'")
        sys.exit(1)

Installation

Create file .git/hooks/prepare-commit-msg (no extension), paste the script and make the file executable.

Usage

For instance with branch feature/ARQ-123
$ git commit -m 'Fixed bug'
will result with commit '[ARQ-653] Fixed bug'

Branch name must be in the format: <feature|epic|hotfix|bugfix>/<ticket number> [-additional-description]
Script handles branching name which is for example used in git-flow. Eg for branch 'hotfix/ABC-399' it will extract ABC-399

Examples

Branch Name	Commit Prefix
feature/ARQ-123	[ARQ-123]
epic/ARQ-123-add-login-form	[ARQ-123]
hotfix/ARQ-123/fixes-the-thing	[ARQ-123]
epic/ARQ-123-authentication	[ARQ-123]
ARQ-123	Invalid branch name

Credits:

• https://andy-carter.com/blog/automating-git-commit-messages-with-git-hooks
• https://gist.github.com/franksteinberg/8dff00204255154ab8190d6974db914e
• http://blog.bartoszmajsak.com/blog/2012/11/07/lazy-developers-toolbox-number-1-prepend-git-commit-messages/

Python3 version in case you don't have v2 installed or python is pointing to python3 in your environment.

import sys, re
from subprocess import check_output

commit_msg_filepath = sys.argv[1]

branch = check_output(['git', 'branch', '--show-current']).decode('utf-8')

# Branch name is empty if in detached HEAD state (e.g. rebase)
if len(branch) > 0 : 
    regex = '(feature|hotfix|bugfix|epic)\/(\w+-\d+)'

    if re.match(regex, branch):
        issue = re.match(regex, branch).group(2)
        with open(commit_msg_filepath, 'r+') as fh: 
            commit_msg = fh.read()
            fh.seek(0, 0)
            fh.write(f'[{issue}] {commit_msg}')
    else:
        print('Incorrect branch name.')
        print('Please use the format <feature|epic|hotfix|bugfix>/<ticket number> [-additional-description]')
        print("e.g. 'feature/CP-1000' or 'hotfix/CP-2500-this-is-the-fix'")
        sys.exit(1)