python script to release gradle project based on commit message in travis-ci environment

travis-release.py

#!/usr/bin/env python

import logging
import os
import re
import subprocess
import sys

logging.basicConfig(format="%(asctime)s %(levelname)s %(message)s", datefmt='%Y-%m-%dT%H:%M:%SZ')
logging.getLogger().setLevel(logging.DEBUG)

git_exec = lambda *args: subprocess.check_call(['git'] + list(args))
gradle_exec = lambda *args: subprocess.check_call(['./gradlew'] + list(args))

def get_release_task(commit_message):
    # e.g. [ci release] or [ci :example:release]
    match = re.search("\[ci (([^][]*:)?release)\]", commit_message)
    if match:
        return match.group(1)
    elif re.match('PUBLISH', commit_message):
        return 'release'

def checkout_branch(branch):
    def decorator(func):
        def wrapper(*args, **kwargs):
            logging.info("Checking out '%s'", branch)
            git_exec('checkout', branch)
            try:
                func(*args, **kwargs)
            finally:
                logging.info('Checking out previous branch')
                git_exec('checkout', '@{-1}')
        return wrapper if branch else func
    return decorator

def main():
    commit = os.environ.get('TRAVIS_COMMIT', 'HEAD')
    commit_message = subprocess.check_output(['git', 'log', '--format=%B', '-n', '1', commit])
    release_task = get_release_task(commit_message)
    if not release_task:
        logging.info("Skipping release")
        return

    # by default Travis checks out in detached mode
    @checkout_branch(os.environ.get('TRAVIS_BRANCH', None))
    def gradle_release():
        logging.info("Running Gradle task '%s'", release_task)
        gradle_exec(release_task, '-Prelease.useAutomaticVersion=true')

    logging.info("Starting release...")
    gradle_release()
    logging.info("Completed release.")

if __name__ == '__main__':
    main()