Git Hooks

Git hooks are shell scripts that execute after an event such as a commit or push.

In the following video, we will take you through the basics of what a Git hook is and demonstrate how to use one in GitKraken Desktop.

Where are Git hooks?

Hooks are stored in the hooks subdirectory of the .git directory. This folder is automatically created when you initialize a new repository in GitKraken Desktop and is located in .githooks in your project directory with a README.sample file in it.

Hooks are unique to your local repository and will not be copied over if you create a new repository nor will be tracked by git. Feel free to add, change, or remove scripts from this folder as necessary.

GitKraken Desktop will seamlessly detect any Git hooks in your repository, but if you are running OSX or Linux, you need to give execution rights to the hook file. If you forgot to set your files to executables, GitKraken Desktop will throw an error as a heads up.

Any script that exits with anything other than exit code 0 is considered a fail.

Define a custom hook path

Users can define a custom path for git hooks by going to Preferences Git Hooks. Browse to the location or enter the path to your git hook folder.

This custom git hook path is defined on a per-repository basis.

What hooks are supported by GitKraken Desktop?

Here are the hooks supported by GitKraken Desktop. Where appropriate, beneath each hook are the actions during which GitKraken Desktop calls that hook:

Git hooks example

Git hooks are scripts that perform automated actions when a specific action is performed in GitKraken Desktop or the command line. The git hook name usually indicates the hook’s trigger (e.g. pre-commit).

Git hooks live under the .git folder of your repo in a directory called hooks. The path to the hooks will look similar to repo/.git/hooks.

Tools needed

• GitKraken Desktop
• Text Editor – I will be using Visual Studio Code
• Terminal – I will be using Gitkraken Terminal

Hook Purpose

In this example, we’ll create a pre-commit hook. This hook validates the git config’s global user email. The hook is useful so that the commits contain the correct committer email address.

Creating the git hook

Step 1

First navigate to the hooks directory for the target repo. Open a Visual Studio Code window and navigate to ~/repo/.git/hooks. From here, add a new file to the .git/hooks directory called pre-commit.

Step 2

Now that we have our pre-commit file, we need to make it executable. To do this we will need the command line.

Open the Gitkraken Terminal window by clicking the Terminal icon in toolbar (or by searching “terminal” in the command palette). Once the terminal is open, change directory to .git/hooks.

Then use the command chmod +x pre-commit to make the pre-commit file executable.

Step 3

Now we create our script using bash. Open the pre-commit file in VS Code as we did before.

The first instruction we need to specify is the shell used in the script, do this by using #!/bin/bash at the beginning of your script for bash or #!/bin/sh if using the sh shell.

This pre-commit hook watches for incorrect commit authors using the script below.

Script variables:
globalEmail – Get email in global git config
workEmail – This is your target email address. The email needed to commit successfully.

In the first condition we validate that the global git config user.email matches with our workEmail. If it fails we will see:

        echo "Commit email and global git config email differ"
        echo "Global commit email: "$globalEmail""
        echo "Committing email expected: $workEmail"
        exit 1

If the condition is successful the script will run and the commit will be made.

Full script

#!/bin/bash

globalEmail=`git config --global --get user.email`
workEmail="[email protected]"

if [[ $globalEmail != $workEmail ]];
then
        echo "Commit email and global git config email differ"
        echo "Global commit email: "$globalEmail""
        echo "Committing email expected: $workEmail"
        exit 1
else
        echo ""
        exit 0
fi

Git hook in action

Environment Variables & Git Hooks

On macOS, GUI applications do not have access to the environment variables set in your shell profile. This means that if you have environment variables set in your shell profile that you want to use in your Git hooks, you need to use the following command:

launchctl setenv YOURVAR variable

Bypass git hooks

There may be times when you want to skip your Git hooks when making a commit. This can be done on a commit-by-commit basis by selecting the Commit and skip hooks option.