Get commit history grouped by tag / user

changelog.py

import argparse
from subprocess import check_output
from datetime import datetime

parser = argparse.ArgumentParser()
parser.add_argument('--dir', default='.', help='Git Directory')
parser.add_argument('--start', help='From Date YYYY-MM-DD')
args = parser.parse_args()

if args.start:
    start_date = datetime.strptime(args.start, "%Y-%m-%d")

git_tags_cmd = "git for-each-ref --sort=taggerdate --format '%(refname) %(taggerdate)' refs/tags"

tags = []
for line in check_output(git_tags_cmd, shell=True, cwd=args.dir).strip().split("\n"):
    parts = line.split(" ")
    name = "".join(parts[0].split("/")[2:])
    date = datetime.strptime(" ".join(parts[1:-1]), "%c")
    tags.append(dict(name=name, date=date))


for i in range(len(tags)):
    if i == 0:
        continue

    if start_date and start_date > tags[i]['date']:
        continue

    tags[i]['changes'] = check_output("git shortlog {0} --not {1}".format(tags[i]['name'], tags[i-1]['name']), shell=True, cwd=args.dir)
    print("{0} - {1}".format(tags[i]['name'], tags[i]['date'].isoformat()))
    print(tags[i]['changes'])
    print('---------------------------------------------')

python changelog.py --dir /my/git/repo --start 2018-01-01 > changes.txt