Home » Software Development » Auto-switchable multiple Git identities on one computer – Git Tricks #1

About Marcin Zajaczkowski

Marcin Zajaczkowski
Marcin is an experienced architect who specializes in creating high quality software. Being under the impression of the Agile methodologies and the Software Craftsmanship movement, he believes in the value of good, testable and maintainable code. He aims to forge good software that makes the client delighted and the team proud of how the code itself looks.In his teaching, as a conference speaker, college lecturer, IT coach and trainer, he shows how to guide software development effectively using tests (with TDD, pair programming, Clean Code, design patterns, etc.) and maintaining a quality-oriented development environment (with CI, Sonar, automatic deployment, etc.).He is also a FOSS projects author and contributor, a Linux enthusiast.

Auto-switchable multiple Git identities on one computer – Git Tricks #1

Have you even committed to Git using wrong email address working on/for different projects/companies? Luckily with a little configuration Git can auto-switch the identities for you.

(Too long) introduction and reasoning

Being an (experienced) IT professional can give you an opportunity to work on different things in the same time frame. For instance, in addition to work for the main client, I do some consultancy stuff with code quality & testing and Continuoues Delivery for other companies. What’s more, I also conduct training sessions (will a lot of exercises with code) and work on my own and other’s FOSS projects. Usually, it is convenient to do it on the same computer. It can happen to commit something with the wrong email address (to be detected later on by an external auditor ;-) ) and a push with force to a remote master after rebase is not the best possible solution :-). I started with some Fish-based script to deal with it, but in the end I have found a built-in mechanism in Git itself.

Disclaimer. This particular blog post doesn’t treat about anything new or revolutionary. However, I’ve been living in unawareness long enough to give my blog readers a chance to know that mechanism right now.

Project situation

My ~/Code directory structure could be simplified to something like that:

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Code/
├── gradle-nexus-staging-plugin
├── mockito-java8
├── spock-global-unroll
├── ...
├── external-foss
│   ├── ...
│   ├── awaitility
│   └── spock
├── training
│   ├── ...
│   ├── code-testing
│   ├── java11
│   └── jenkins-as-code
└── work
    ├── ...
    ├── codearte
    └── companyX

The goal is to keep an email address in the company’s projects appropriate.

Solution

The first idea which can spring to your mind is to manually override git config user.email "..." in every clonned company repository. However, it’s tedious and error prone (especially in the microservice-based architecture :) ).

Luckily, one of the features introduces in Git 2.13.0 (long time ago – May 2017) is a conditional configuration applying (aka Conditional includes). Armed with it our task is pretty simple.

First, keep your default name and email defined in the [user] section in ~/.gitconfig:

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[user]
  name = Marcin Zajączkowski
  email = foss.hacker@mydomain.example.com

Next, create a company related config file in the home directory, e.g. ~/.gitconfig-companyX with just overriden email address:

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[user]
  email = marcin.zajaczkowski@companyx.example.com

Glue it together by placing in ~/.gitconfig the following code:

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[includeIf "gitdir:~/Code/work/companyX/"]
  path = .gitconfig-companyX

The .gitconfig-companyX is applied only if a current path prefix matches the one defined in includeIf. Simple, yet powerful. That mechanism can be also used to configure different things – such as conditionally using GPG to sign your commits.

Btw, being a paranoid you can even remove the email field from the root configuration to be notified if you forgot to add an email for any new company you colaborate with.

Summary

Thanks to the includeIf mechanism you will never (*) again commit to a repo with wrong name or email. That and other Git related tricks and commands/aliases (such as collected in git-kurka make it easier to focus on delivering the stuff :).

Feel free to leave your favorite Git tips & tricks in the comments.

The lead photo based on the Elias Sch‘s work published in Pixabay, Pixabay License.

Published on Java Code Geeks with permission by Marcin Zajaczkowski, partner at our JCG program. See the original article here: Auto-switchable multiple Git identities on one computer – Git Tricks #1

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