An illustration of using Git hooks for automation.
January 3, 2020

How to Use Git Hooks to Automate Your Workflows

Git at Scale
Version Control

What Is a Git Hook?

Git hooks are scripts that help automate tasks before or after certain Git commands are executed. You can use Git hooks to customize and automate Git to trigger actions during your development lifecycle. These are generally used for pre-commit checks on the server side.

Git hooks can be used to:

  • Check commits for errors before they are pushed.
  • Ensure code meets project standards.
  • Notify team members about changes.
  • Push code into a production environment, and more.

Why You Should be Using Git Hooks for Automation

Although you can use git hooks for a variety of reasons, they are very effective if you have or are implementing Continuous Integration/ Continuous Delivery (CI/CD). It can help remove bottle necks in your workflow and keep teams productive.

For example, you can push changes to your staging area or a production environment without ever having to leave Git. This makes developers’ changes available immediately for testing.

How Do Git Hooks Work

Working with hooks is a matter of writing scripts in the .git/hooks subdirectory for a repository. This subdirectory is preloaded with example scripts to get your started.

Git hooks support both client-side and server-side automation.

Client-Side Git Hooks

Client-side hooks are available for pre-commit, pre-rebase, post-checkout, and post-merge, etc. They provide a fair amount of flexibility for workflows on a local machine. These are not copied with cloning a repository.

Adding hooks to client-side will not enforce a policy across your organization. To implement automation, you need to use a server-side hook.

Server-Side Git Hooks

Server-side hooks work like client hooks, but they are stored in the server repository. They run before or after changes are pushed to the server. If conditions are not met, these hooks can reject a push and send an error back to the client. Examples include:

  • Pre-receive hooks that run when changes are pushed from a client.
  • Update hooks that run once on each branch being updated prior to changes being accepted.
  • Post-receive hooks that run after the push process is completed to notify other users.

Setting Up Git Hooks

By default you’ll find the following in the .git/hooks folder :

    applypatch-msg.sample
    commit-msg.sample
    post-update.sample
    pre-applypatch.sample
    pre-commit.sample
    pre-push.sample
    pre-rebase.sample
    prepare-commit-msg.sample
    update.sample

 

These files provide examples of how to build hook scripts for the various types of tasks. Built-in scripts are mostly written in PERL, but you can use any scripting language (as long as it can be executed).

To set them up you need to:

  1. Copy an example to the same name.
  2. Delete the .sample extension.
  3. Edit it as needed.

The hook will execute the next time it’s triggered.

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Want to learn more? Explore Git best practices.