Git & Version Control

Git Basics

# Configure Git
git config --global user.name "Your Name"
git config --global user.email "you@example.com"
git config --global init.defaultBranch main

# Initialize a repository
git init
git add .
git commit -m "Initial commit"

# Basic workflow
git status                   # Check what's changed
git add file.txt             # Stage specific file
git add .                    # Stage all changes
git commit -m "feat: add user auth"  # Commit with message
git log --oneline --graph    # View commit history

Branching

# Create and switch to a branch
git checkout -b feature/user-auth

# List branches
git branch -a

# Switch branches
git checkout main

# Merge a branch
git checkout main
git merge feature/user-auth

# Delete a branch
git branch -d feature/user-auth
git push origin --delete feature/user-auth

Remote Repositories

# Clone a repository
git clone https://github.com/user/repo.git

# Add remote
git remote add origin https://github.com/user/repo.git

# Push changes
git push origin main
git push -u origin feature/new-api

# Pull changes
git pull origin main

# Fetch without merging
git fetch origin

Git Workflows

Trunk-Based Development (Recommended for DevOps)

• Short-lived feature branches (< 1 day)
• Frequent integration to main
• Feature flags for incomplete features
• CI runs on every commit

Git Flow

• main — Production-ready code
• develop — Integration branch
• feature/* — New features
• release/* — Release preparation
• hotfix/* — Production fixes

Merge vs Rebase

# Merge — preserves history, creates merge commit
git checkout main
git merge feature/api

# Rebase — linear history, rewrites commits
git checkout feature/api
git rebase main

# Interactive rebase (squash, reword, reorder)
git rebase -i HEAD~5

# Golden rule: Never rebase public/shared branches

Advanced Commands

# Stash changes
git stash
git stash list
git stash pop
git stash apply stash@{0}

# Cherry-pick a commit
git cherry-pick abc1234

# Bisect — find the commit that introduced a bug
git bisect start
git bisect bad               # Current commit is bad
git bisect good v1.0         # v1.0 was good
# Git will checkout commits for you to test
git bisect good              # or git bisect bad
git bisect reset             # When done

# Reset (dangerous — know what you're doing)
git reset --soft HEAD~1      # Undo commit, keep staged
git reset --mixed HEAD~1     # Undo commit, unstage
git reset --hard HEAD~1      # Undo commit, discard changes

# Reflog — recover lost commits
git reflog
git checkout HEAD@{5}

GitOps

GitOps uses Git as the single source of truth for declarative infrastructure and applications. Any changes to the system are made through Git commits.

Git Hooks

# .git/hooks/pre-commit
#!/bin/bash
# Run linting before commit
npm run lint
if [ $? -ne 0 ]; then
  echo "❌ Linting failed. Fix errors before committing."
  exit 1
fi

# .git/hooks/commit-msg
#!/bin/bash
# Enforce conventional commits
if ! grep -qE "^(feat|fix|docs|style|refactor|test|chore|ci|perf)(\(.+\))?: .+" "$1"; then
  echo "❌ Commit message must follow conventional commits format"
  echo "Example: feat(auth): add OAuth2 support"
  exit 1
fi

# Use Husky for managing hooks (npm projects)
npx husky init
echo "npm run lint" > .husky/pre-commit