Oct 12, 2018

Integrating git into our development workflow

As developers, we all are using git/github in our projects. Our most commonly used command are git add git commit git push git pull, which are used for managing version of our code. We generally don’t us these commands as helpers to improve our development workflow. Wouldn’t it be nice if we can run linter on our new changes before committing, running tests before pushing our changes to remote, maintaining a commit message format for easy understanding it. We actually can. Let’s see how.

Git hooks

What we need for doing our tasks before some git operations ? Well Git Hooks. Git hooks are ways to hook into git workflow like staging changes, committing, pushing etc. Git Hooks (i.e. pre-commit, prepare-commit-msg, commit-msg, post-commit, post-commit, update etc) are stored in hooks subdirectory in a git repository, in most projects, they are in .git/hooks. Git provides some really helpfull git hook samples in .git/hooks directory. We can categories these hooks in two categories: Client side hooks and Server side hooks. As name suggest, Client side hooks stays on developer’s machine to help them integrate in there workflow whereas Server side hooks are for Manager which want to enforce some policies over PRs.

Client side hooks

NOTE: .git is not copied over push/pull

We we browse content from .git/hooks directory, we see some sample hooks. Sample codes are written in ruby or in bash but any scripting language can be used for git hooks. Just pick any sample and remove sample from end and make it excutable to see it working. Let’s do it together. Create a new git directory.

mkdir git-hooks
cd git-hooks
git init
touch README.md
git add .
mv .git/hooks/commit-msg.sample .git/hooks/commit-msg

Now put following content in the .git/hooks/commit-msg file.

# first argument contains the file path to the commit message file

echo "Your commit message is:"
cat $1 # print the content of the commit message file which is basically out commit message
exit 1 # any non-zero status will abort the process

Now save it and make it executable chmod +x .git/hooks/commit-msg. Now run git commit -m "init commit" and you should see our message output with commit aborted (try git status to see staged changes ready to commit)

Simillar to this, there are some other git hooks which can be utilized in our workflow. A complete list can be found here. Following hooks are generally used.

pre-commit: This is the first hook that gets called when we run git commit. We normally run our linter and test (only relevant) on the staged files (we can get them by git diff --name-only --cached) in this hook.
commit-msg: This hooks gets called when git is about to commit the changes. Here we get the commit message file path as argument and can easily enforce a commit policy on client side.
pre-push: This hook gets called before pushing our changes to remove. We can use this hook to run all tests to make sure everything is working fine.

Server side hooks

Server side hooks are created in the same way as we create our client side hooks, but they presist on server where pushes and PRs are handled to enforce some development policies.