Git: conditional configurations

June 11, 2017
(git)

More than five years ago Jeff King has added include directive to git config subprogram. This directive allows splitting configuration file across multiple files. A nice feature by itself was boosted in Git 2.13.0 by adding conditional includes - one of my favourite features of this release. And something that makes me sad.

Consider a simple example of ~/.gitconfig file.

# content of ~/.gitconfig

[core]
    editor = emacsclient

[user]
    useconfigonly = true

[include]
    path = ~/.gitconfig_machine_specific
    path = ~/.gitconfig_sensitive

# include ~/.gitconfig_personal only when active repository is under
# ~/Projects/personal/
[includeIf "gitdir:~/Projects/personal/"]
    path = ~/.gitconfig_personal

# include ~/.gitconfig_work only when active repository is under
# ~/Projects/work/
[includeIf "gitdir:~/Projects/work/"]
    path = ~/.gitconfig_work

As you can see, using include and includeIf directives allows to achieve following things.

  1. File ~/.gitconfig can be shared among different computers as machine specific configurations are included as a separate file (~/.gitconfig_machine_specific).
  2. File ~/.gitconfig can be made public as all sensitive configurations are included as a separate file (~/.gitconfig_sensitive).
  3. You can set some configurations based on git repository location (e. g. personal or work).

Please note that these directives can be used in any git configuration level (system level, user level, repository level or individual command invocation). Which makes it even more powerful.

Also, note that the only condition implemented now is gitdir that matches against repository path.

The same but different

Almost a year ago I have created a tool named git-config-manager. The idea is simple1, you have several configuration schemes which you may apply on a repository level. For example, you may use one name, email address and commit sign key when working on open source projects and totally different identity when committing to your day job repository. You just ask the tool to set one or several schemes in current repository and it loops through key-values and sets them using git config. Nothing fancy.

With git-config-manager you define schemes in a single json file.

When you ask git-config-manager to set configurations from the personal scheme ($ git-config-manager set personal), it takes the definition and calls git config for every configuration key-value pair. This is really straightforward.

But the simple approach has several drawbacks. First of all, you have to manually call git-config-manager set scheme (from the terminal or using the magit extension). While with includeIf directory everything is handled automatically. Secondly, if you wish to change configuration piece in all affected repositories (e. g. update sign key in all work projects), git configuration system allows you to make the change in one place (in the ~/.gitconfig_work file) and it will be automatically propagated to all affected repositories. With git-config-manager it’s not that simple because it just sets values when it’s asked to set.

What’s the point?

When I learned about includeIf directory I thought that the time has come to deprecate git-config-manager. But then I realised that while they overlap in use cases, I might implement several new features I’ve been thinking about lately.

So again, stay tuned. Meanwhile, please read about other changes in Git 2.13.0.


  1. The idea is simple, but solution is slightly over-engineered. Mostly because I didn’t know about include directive in the first place. And partly because I wanted to write it in Haskell.