Setting up project-level gitconfig

Last week, I completely shifted my system to Arch Linux and during this process, I lost some config(s), settings, etc.

git config was one of them. I used to have a separate config like username, email, ssh key to use based on which project I was working on.
For example, my work projects require a different set of credentials (username, email, ssh-key) than the credentials I use on my personal projects.

I have done this before too but, after a while, I just tend to forget how to do it. This time, I am writing it in a post so that I can refer to it when required.

Steps

1. Go to the directory where you store the projects and create a .project.gitconfig with the desired credentials:

[user]
    name = work-username
    email = username@work-domain.com

1. Edit the user level .gitconfig present under $HOME/.gitconfig to include the following condition:

[includeIf "gitdir:ABSOLUTE_PROJECT_DIRECTORY_PATH"]
    path = "ABSOLUTE_PROJECT_DIRECTORY_PATH/.project.gitconfig"

Basically, we are telling git:

"If you find a .git directory nested under this path then, use these set of credentials."

Verify

Now, go to a project inside the work/project-root directory and verify that the correct credentials is being used:

git config --list | grep -P "user|email"

Note (or Gotcha)

Keep in mind that this config will only be used by git if it finds .git directory at that path or a parent .git directory.
For example:

work/
|- .work.gitconfig
|- project-a/
   |- .git/
|- project-b/
   |- .git/

Now, my .work.gitconfig will be used when I am inside project-a or project-b but, not inside work.