Git hooks are a good way of enforcing controls on events within a git repository. There are two types of git hooks.

1. Client-side hooks
2. Server-side hooks

Client-side hooks

This may be obvious, but the client-side hooks are designed to control actions that the git user typically does client side. Examples of this are git commit commands are controlled by pre-commit hooks. Note the convention…some are named with the pre- prefix signifying that it runs before some event, and some are named with the post- prefix signifying that it runs after some event.

These are stored in the repo’s /.git/hooks directory. There are sample hooks in the hooks directory that are not active with the post-fix of .sample. If you remove the post-fix and do a chmod +x <filename> on the hook, it will become active.

Here is an example of the /.git/hooks/ directory:

Things that you may want to control with client-side hooks are:

• Allow a commit, if all unit tests execute cleanly without errors
• Allow a commit, if the commit message contains a Jira ticket prepended to the developer’s commit message
• Allow a commit, if a code linter executes cleanly without errors

Something to note with this technique is that client-side hooks are not stored as part of the repository. So, as an example, if you have a client-side hook on repo 123 of your laptop and go to a second machine with a clone of repo 123, the second machine will not have the client-side hook in the /.git/hooks directory. I will discuss ways to share these types of hooks in future blog posts.

Server-side hooks

If you are hosting your git repository in a host like GitHub, Bitbucket, etc, you can also have a server-side hook. The types of events that can be controlled on the server-side is a bit different because it focused on network events. An example of this is the pre-push hook, which controls the git push event on the server-side (host’s side). I will post more about server-side hooks in future blog posts.

For a good listing of git hooks, see digtial ocean’s blog.