pre-commit hook to prevent committing a Helm chart change without bumping Chart.yaml

chart-bump-pre-commit.py

#!/usr/bin/env python3

"""Check a git commit for changes to charts with no bumps of Chart.yaml"""

import os
import re
import subprocess
import sys

def command(command_s: str) -> (str, str):
    with subprocess.Popen(command_s.split(" "),
                          stdout=subprocess.PIPE, stderr=subprocess.PIPE) as command_p:
        stdout, stderr = command_p.communicate()
        if command_p.returncode:
            raise Exception(f"Failed to execute process {command_s}: {stderr}")
        return stdout.decode()

def check_amend() -> bool:

    ppid = os.getppid()
    ps_output = subprocess.Popen(["ps", "-f", "-p", str(ppid)],
                                 stdout=subprocess.PIPE,
                                 stderr=subprocess.PIPE)
    if "--amend" in ps_output.communicate()[0].decode():
        return True
    return False

def main():

    if check_amend():
        # If the commit is an amend, assume that we have already run
        # the hook on the base commit
        sys.exit(0)

    changed_files = command("git diff HEAD --name-only")
    changed_charts = set()
    bumped_charts = set()

    for changed_file in changed_files.strip().split("\n"):
        chart_match = re.match("^charts/([\w-]+)/(.*)", changed_file)
        if chart_match:
            chartname, chartrest = chart_match.groups()

            changed_charts.add(chartname)
            if chartrest == "Chart.yaml":
                bumped_charts.add(chartname)

    not_bumped = changed_charts.difference(bumped_charts)
    if not_bumped:
        print("Charts changed without Chart.yaml bumped: {}".format(",".join(not_bumped)))
        sys.exit(1)

if __name__ == "__main__":
    main()