GitHooks

Pre-Commit setup example which can be shared with other. Using gitleaks for detecting secrets prior to commit.

• What are Git hooks and how can they help improve developer experience??
  • When to use Git hooks?
  • When not to use Git Hooks
• Can this replace pipeline steps or actions?
• What tools should I run part of my githooks?
  • Development Tools
  • Security Tools
• How to setup a githook?
• What hooks are available?

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What are Git hooks and how can they help improve developer experience?

Git hooks are scripts triggered on a given git event(commit, push). Git hooks should be used to improve developer experience. Using custom scripts we can improve developer experience by shortening the feedback loop and automating the following(not limited):

• Linting
• Formatting
• Versioning
• Commit message formatting
• Running tests prior to pushing changes
• Security code scanning(secrets, vulnerable code)

When to use Git hooks?

• Enforce Coding Standard(linting,formatting)
• Automate tasks(versioning, unit-tests)

When not to use Git hooks?

• Impose Personal Prefrences
• Running checks/tools that disrupt developer flow (long running checks - ideally your checks/hooks should not run for longer than 15 seconds)

Can this replace pipeline steps or actions?

No. Githooks should be used in conjunection with the pipeline as they act as a preliminerary gate on the developers device rather than in the central repository. The hooks should detect/catch major of the issues that will be found later on.

• Faster feedback loop for devs (don't have to wait for maintainers or pipeline steps to run)
• Code pushed to PR meets standards prior to review - Linting/Formatting should be lower priority for maintainers when reviewing code as this can be automated.
• Cheaper(Time vs Resource) to fix issues when they are caught as the code is commited rather than when its in production and identified months later.
• Save Cost on Build Minutes - why run entire pipeline just to findout the code does not meet standards. Some pipeline run for 10 minutes or longer.

What tools should I run part of my git hooks?

I'm not sure. As githooks act as the first set of checks/gates in a SDLC which is why it is important these only catch the most common issues and run automation which reduces the effort required by the reviewer to review the code. So, for example linters and formatter the maintiners do not want to spend time on enforcing standards why its a waste of their time and can be automated. These tools should not hinder the developer experience. Remember these are tools to help standardize good practicies and such should only run tools to catch issues early/faster.

Development Tools

• Code Linter
• Code Formatter
• Test Status Checker(all test must pass prior to push)

Security Tools

• Scan for vulnerable code
• Scan for vulnerable dependencies
• Scan for hardcoded secrets

How to setup a githook?

• Create a directory named hooks in the root of your project.
• Create a bash executeable script named setup.sh in the hooks directory.
• Add the following code to setup.sh - source.

DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

cd "${DIR}/.."

# Symlink git hooks
for filename in ${DIR}/git/*; do
	filename=$(basename ${filename})
	ln -s "../../hooks/git/${filename}" ".git/hooks/${filename}"
	if test -f ".git/hooks/${filename}.sample"; then
		rm -f ".git/hooks/${filename}.sample" # removes the .sample from the file
	fi
done

• Create a sub-directory in the hooks directory named git which will now contain our hooks.
• Create a file with the same name as the hook that you want to setup. In this case lets setup a pre-commit hook.
• Add the code you want to run when a user attempts to commit code. Maybe run a linter or formatter. Try adding echo ("Running prior to commit code";
• Now when run the ./hooks/setup.sh to setup the symlink between your hook in the hook/git/pre-commit and .git/hooks/pre-commit.
• Now try to commit some code and you will the the line Running prior to commit code printed before your code is commited.

What hooks are available?

Available commits can be viewed in the ./git/hooks/ directory. See also git hooks

• applypatch-msg
• commit-msg
• fsmonitor-watchman
• post-update
• pre-applypatch
• pre-commit
• pre-merge-commit
• pre-push
• pre-rebase
• pre-receive
• prepare-commit-msg
• push-to-checkout
• update.sample