Git Hooks

Trunk supports triggering actions on all githooks

Features

• Seamlessly bring git-hooks under version control. git-hooks can be a major headache for organizations - they require manual installation and are not easily versioned along with the rest of your code.

• Take advantage of Trunk's powerful sandboxing and environment management to write and execute hooks using the programming language and runtime of your choice, as opposed to dealing with complicated bash scripts.

Manual Installation

trunk git-hooks sync

Automatic Installation

Trunk will automatically install and begin managing your githooks if you have any actions enabled in trunk.yaml which trigger from git events.

Triggering an action from a githook

As an example let's examine how we implement the git-lfs action in the plugins repo.

Definition

- id: git-lfs
  display_name: Git LFS
  description: Git LFS hooks
  run: git lfs "${hook}" "${@}"
  triggers:
    - git_hooks: [post-checkout, post-commit, post-merge, pre-push]

Template resolution

As documented by git, each githook generates a variable number of parameters that can be referenced in the run entry for the action.

The following special variables are made available for template resolution when reacting to a git event:

Variable	Description
${hook}	Hook that triggered this action (e.g. pre-commit, pre-push)
${1},${2}, ${3}, etc...	Positional parameters passed by git to the hook
${@}	All parameters passed to the hook

Interactivity

interactive: true

Setting interactive to true will allow your githook action to be run from an interactive terminal. This enables you to write more complicated hooks to react to user input.

Testing a githook action

The following command will simulate a githook event and execute all of the enabled actions for the provided hook in the order you defined them.

trunk git-hooks callback <hook> -- <args>

Alternatively, once an action is enabled you can call git and debug with the actual git provided data. This is sometimes easier since some git parameters point to txt files etc...and fabricating those formats through manual testing can be tricky.

Debugging a githook action

You can observe the actions that are triggered by a git event by calling:

trunk actions history <action-name>

Which will print out the last 10 executions including timestamps of the specified action \

trunk actions history for git-lfs action

Uninstalling

Remove all actions that are triggered by githooks from trunk.yaml and run

git config --unset core.hooksPath