DevOps Classroom Series – 21/Feb/2021 (Evg)

Git Hooks are scripts that run automatically every time a particular event occurs in Git Repository
Git Hooks are located in the .git/hooks
Git Hooks call the scripts which can be in any scripting language
Git Hooks are of two types
- Client Side Hooks:
  - These are executed on the commiter’s system
  - This can be further categorized as
    - Commiting workflow hooks
    - Email Workflow Hooks
    - Other
- Server-Side Hooks: These are executed on the remote repository. These are divided into following categories.
  - Pre-receive and Post-receive hooks
  - Update
- Server Side Hooks are the scripts which are executed on server, but if the organization is using cloud/hosted repositories like GitHub/Code Commit/ Azure Source Repos/Bit Bucket then web hooks are enabled.
Some of the popular hooks
- applypatch-msg: Invoked by git am
- pre-applypatch:
- post-applypatch:
- pre-commit: executed by git commit
- prepare-commit-msg: executed by git commit
- commit-msg: executed by git commit
- post-commit: executed by git commit
- pre-rebase
- post-checkout: git checkout and git clone
- post-merge: git merge and git pull
- pre-push
- pre-recieve
- update
- post-recieve
- post-update
Sample pre-commit hook

#!/bin/bash
echo " precommit"
set

With hooks whenever developer submits code we can execute functionality by calling hook scripts, So when developer submits code we can call
- Jenkins to build
- Ansible to deploy
- Terraform to deploy
If you do these kind of activities where your pipeline is triggered as part of git hook it is also referred as git ops.
In the case of git hub we can configure web hooks and from there call the pipeline