Git trick #628: automatically set commit author based on repo URL

Standard

If you have more than one email identity that you use to commit to different projects you have to remember to change it in .git/config every time you git clone a new repository. I suck at remembering things and it’s been annoying me for a long time that I kept pushing commits with wrong email addresses to wrong repositories.

I can’t believe I am the only one having this problem, but I could not find anything on the interwebs so I just fixed it myself and I’m posting it here so that maybe hopefuly someone else will find it useful too :).

The trick is very simple: we create a post-checkout hook that will check the value of user.email in .git/config and set it to whatever we want based on URL of the “origin” remote.  Why post-checkout? Because there’s no post-clone hook, but git automatically checkouts master after clone so the hook gets executed. It also gets executed every time you run git checkout by hand but the overhead is minimal and we have a guard against overwriting the identity in case it’s already set.

#!/usr/bin/python
# -*- coding: utf-8 -*-
#
# (C) 2015 Daniel Vrátil <dvratil@kde.org>
# License: GPL
#
# Requires: Python 2 or 3 and compatible GitPython
#

# https://github.com/gitpython-developers/GitPython
import git
import ConfigParser
import os
import sys

repo = git.Repo(os.getcwd())

# Don't do anything if an identity is already configured in this
# repo's .git/config
config = repo.config_reader(config_level = 'repository')
try:
    # The value of user.email is non-empty, stop here
    if config.get_value('user', 'email'):
        sys.exit(0)
except (ConfigParser.NoSectionError, ConfigParser.NoOptionError):
    # Section or option does not exist, continue
    pass


origin = repo.remote('origin')
if not origin:
    print('** Failed to detect remote origin, identity not updated! **')
    sys.exit(0)

# This is where you adjust the code to fit your needs
if 'kde.org' in origin.url or origin.url.startswith('kde:'):
    email = 'dvratil@kde.org'
elif 'fedoraproject.org' in origin.url:
    email = 'dvratil@fedoraproject.org'
elif 'kdab.com' in origin.url:
    email = 'daniel.vratil@kdab.com'
else:
    print('** Failed to detect identity! **')
    sys.exit(0)

# Write the option to .git/config
config = repo.config_writer()
config.set_value('user', 'email', email)
config.release()
print('** User identity for this repository set to \'%s\' **' % email)

To install it, just copy the script above to ~/.git-templates/hooks/post-checkout, make it executable and run

git config --global init.templatedir ~/.git-templates

All hooks from templatedir are automatically copied into .git/hooks when a new repository is created (git init or git clone) – this way the hook will get automatically deployed to every new repo.

And here’s a proof that it works :-)

[dvratil@Odin ~/devel/KDE]
$ git clone kde:kasync
Cloning into 'kasync'...
remote: Counting objects: 450, done.
remote: Compressing objects: 100% (173/173), done.
remote: Total 450 (delta 285), reused 431 (delta 273)
Receiving objects: 100% (450/450), 116.44 KiB | 0 bytes/s, done.
Resolving deltas: 100% (285/285), done.
Checking connectivity... done.
** User identity for this repository set to 'dvratil@kde.org' **

[dvratil@Odin ~/packaging/fedpkg]
$ git clone ssh://dvratil@pkgs.fedoraproject.org/gammaray
Cloning into 'gammaray'...
remote: Counting objects: 287, done.
remote: Compressing objects: 100% (286/286), done.
remote: Total 287 (delta 113), reused 0 (delta 0)
Receiving objects: 100% (287/287), 57.24 KiB | 0 bytes/s, done.
Resolving deltas: 100% (113/113), done.
Checking connectivity... done.
** User identity for this repository set to 'dvratil@fedoraproject.org' **

Update 1: added utf-8 coding (thanks, Andrea)
Update 2: changed shebang to more common /usr/bin/python (/bin/python is rather Fedora-specific), added “Requires” comment to top of the script (thanks, Derek)

6 thoughts on “Git trick #628: automatically set commit author based on repo URL

  1. Aurélien Gâteau

    Oh, that’s awesome! Didn’t know about the ~/.git-templates dir… so much new possibilities!

  2. Derek Bassett

    These instructions are great, a couple of things though, your script requires python installed and also has a dependency on gitpython being installed as well.
    Also on the Mac the python located at either /usr/bin/python or /usr/local/bin/python not /bin/python.
    So you might want to throw some requirements up at the top of your post.
    Once I got those two things resolved I had no problems either. Thanks great script.

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