Example of extracting and flattening git logs and writing them into BigQuery

bq_load.sh

#Copyright 2022 Google LLC.
#SPDX-License-Identifier: Apache-2.0

bq --location="EU" load \
    --replace \
    --source_format="NEWLINE_DELIMITED_JSON" \
    --autodetect \
    your_dataset.your_table \
    ./logs.jsonl

example_output.jsonl

{"commit_hash": "1e0e4b74e2fad3a", "commit_subject": "Example commit 1", "author_name": "Author 1", "author_email": "[email protected]", "author_date": "1655894118", "commiter_email": "[email protected]", "commiter_name": "GitHub", "file": "tools/sometool1/file.py\n"}
{"commit_hash": "e551dd384acc13f", "commit_subject": "Example commit 2", "author_name": "Author 2", "author_email": "[email protected]", "author_date": "1655821884", "commiter_email": "[email protected]", "commiter_name": "GitHub", "file": "tools/sometool2/path/config.yaml\n"}
{"commit_hash": "f96748b7b3b8f54", "commit_subject": "Example commit 3", "author_name": "Author 3", "author_email": "[email protected]", "author_date": "1655797941", "commiter_email": "[email protected]", "commiter_name": "GitHub", "file": "tools/sometool3/README.md\n"}
{"commit_hash": "f96748b7b3b8f54", "commit_subject": "Example commit 3", "author_name": "Author 3", "author_email": "[email protected]", "author_date": "1655797941", "commiter_email": "[email protected]", "commiter_name": "GitHub", "file": "tools/sometool3/src/main/java/functions/SendNotification.java\n"}
{"commit_hash": "f96748b7b3b8f54", "commit_subject": "Example commit 3", "author_name": "Author 3", "author_email": "[email protected]", "author_date": "1655797941", "commiter_email": "[email protected]", "commiter_name": "GitHub", "file": "tools/sometool3/src/main/java/functions/eventpojos/PubSubMessage.java\n"}
{"commit_hash": "f96748b7b3b8f54", "commit_subject": "Example commit 3", "author_name": "Author 3", "author_email": "[email protected]", "author_date": "1655797941", "commiter_email": "[email protected]", "commiter_name": "GitHub", "file": "tools/sometool3/src/test/java/functions/SendNotificationTest.java\n"}

example_run.sh

#Copyright 2022 Google LLC.
#SPDX-License-Identifier: Apache-2.0

python extract.py \
    --git-dir='/path/to/your/repository/.git' \
    --branch='main' \
    --output='./logs.jsonl'

gitlogs_to_jsonl.py

#Copyright 2022 Google LLC.
#SPDX-License-Identifier: Apache-2.0
"""
A simple script for extracting and flattening git logs per commit into:
file, commit, subject, author, commiter, date. formatted as JSONL,
compatible for loading into BigQuery
"""
import io
import json
import re
import argparse
import subprocess


def get_logs(git_dir, fields, branch):
    """
    Runs a git log command and returns output results line by line
    """
    pretty_format = '%n'.join([f'{k}: {v}' for k, v in fields])

    command = [
        'git', '--git-dir', git_dir, 'log', f'origin/{branch}', '--name-only',
        f'--pretty=format:{pretty_format}'
    ]

    proc = subprocess.Popen(command, stdout=subprocess.PIPE)
    for line in io.TextIOWrapper(proc.stdout, encoding='utf-8'):
        yield line


def parse_logs(logs, fields):
    """
    Iterate through a git log output line by line, flatten by yielding
    a log item for every file in each commit. Each new log item is a
    dict containing file name, author, commit hash, commit date etc...
    """
    state = {k: None for k, v in fields}
    file_path_pattern = re.compile(r'^([a-zA-Z_\-\s0-9]+)(\/[a-zA-Z_\-\s0-9\.]+)+(\.[a-zA-Z]+)?$')
    commit_detail_pattern = re.compile(r'^(?P<type>.*): (?P<value>.*)')

    for line in logs:
        if file_path_pattern.match(line):
            temp_out = dict(state)
            temp_out['file'] = line
            yield temp_out
        else:
            matches = commit_detail_pattern.match(line)
            if matches:
                groups = matches.groups()
                k = groups[0].strip()
                if k in state:
                    state[k] = groups[1].strip()


def main():
    parser = argparse.ArgumentParser(
        description='Utility to extract git logs into jsonl')
    parser.add_argument('--git-dir',
                        required=True,
                        help='Git directory to read logs from')
    parser.add_argument('--branch',
                        required=True,
                        help='Git branch to read logs from')
    parser.add_argument('--output',
                        required=True,
                        help='Target file to write transformed logs to')

    args = parser.parse_args()

    fields = [('commit_hash', '%H'), ('commit_subject', '%s'),
              ('author_name', '%aN'), ('author_email', '%aE'),
              ('author_date', '%at'), ('commiter_email', '%ce'),
              ('commiter_name', '%cn')]

    logs = get_logs(args.git_dir, fields, args.branch)

    parsed_logs = parse_logs(logs, fields)

    with open(args.output, mode='w', encoding='UTF-8') as file:
        for line in parsed_logs:
            file.write(f'{json.dumps(line)}\n')


if __name__ == '__main__':
    main()