Git for DevOps: The Essential Guide to Version Control

Welcome back to the No BS DevOps: Zero to One series. In our first post, we established the foundation with Linux and networking fundamentals. Now, we're diving into the next essential pillar for any DevOps engineer: version control with Git.

Core Git Workflow

Understanding the basic Git workflow is crucial:

Working Directory → git add → Staging Area → git commit → Local Repository → git push → Remote Repository

Why the Staging Area?

The staging area acts as a buffer between your working directory and commits. This allows you to:

• Review changes before committing
• Stage only specific files or parts of files
• Create focused, logical commits

Essential Commands

# Check status of working directory and staging area
git status

# View commit history
git log
git log --oneline --graph  # Compact view with branch visualization

# Configure Git (do this once)
git config --list
git config --global user.name "Your Name"
git config --global user.email "[e-mail]"

Repository Setup

Connecting Local to Remote

# Add remote repository
git remote add origin [e-mail]:username/repository.git

# Push and set upstream tracking
git push --set-upstream origin master

Branching Strategies

Feature vs Trunk-Based Development

Feature-Based (Traditional):

• Create separate branches for each feature/bugfix
• Merge back to main branch via pull requests
• Good for larger teams, complex features

Trunk-Based (Modern DevOps):

• Work directly on main branch or very short-lived branches
• Frequent small commits
• Enables faster CI/CD cycles
• Requires good testing practices

Branch Operations

# Switch to existing branch
git checkout branch_name

# Create and switch to new branch
git checkout -b branch_name

# Push new branch to remote
git push --set-upstream origin branch_name

# Delete local branch after merge
git branch -d branch_name

Handling Changes and Conflicts

Pulling Changes

When someone else pushes changes:

# Standard pull (creates merge commit)
git pull

# Rebase pull (cleaner history, no merge commit)
git pull -r

Merge Conflicts

When Git can't automatically merge changes:

1. Git marks conflicted files
2. Manually edit files to resolve conflicts
3. Stage resolved files: git add conflicted_file
4. Continue rebase: git rebase --continue
5. Push changes: git push

Pull/Merge Requests

Essential for code review and collaboration:

• Purpose: Request to merge one branch into another
• Process: Create → Review → Approve → Merge
• Benefits: Code review, discussion, quality control

Managing Files

.gitignore

Exclude files/directories from version control:

# Create .gitignore file
echo ".idea/" >> .gitignore
echo "*.log" >> .gitignore

# Remove already tracked files
git rm -r --cached .idea
git commit -m "Remove .idea from tracking"

Temporary Storage

# Temporarily store changes
git stash

# Retrieve stashed changes
git stash pop

Viewing History and Navigation

# View commit history with graph
git log --oneline --graph

# Go to specific commit (detached HEAD)
git checkout commit_hash

# Return to latest commit
git checkout branch_name

Undoing Changes

Local Changes (Use Carefully)

# Undo last commit, keep changes in working directory
git reset --soft HEAD~1

# Undo last commit, discard changes completely
git reset --hard HEAD~1

# Modify last commit (add changes or fix message)
git add .
git commit --amend

Remote Changes (When Working Alone)

# Remove commit from remote (dangerous!)
git reset --hard HEAD~1
git push --force

Safe Undoing (Team Environment)

# Create new commit that undoes previous commit
git revert commit_hash

Rule of Thumb: Use reset when working alone, use revert when working in a team.

Branch Merging

# Merge source_branch into current branch
git checkout target_branch
git merge source_branch

Key Takeaways for DevOps

1. Infrastructure as Code: Your Terraform files, Ansible playbooks, and Kubernetes manifests should live in Git
2. Automation Scripts: Python scripts, shell scripts, and other automation tools need version control
3. CI/CD Integration: Build systems need to interact with Git repositories
4. Collaboration: Even infrastructure changes need code review through pull requests
5. Rollback Capability: Git history allows you to rollback infrastructure changes safely

Best Practices

• Write descriptive commit messages
• Commit small, related changes together
• Pull frequently to stay in sync
• Don't push directly to main/master branch
• Use meaningful branch names: feature/user-auth, bugfix/memory-leak
• Set up proper .gitignore files for your projects
• Use git pull -r to maintain clean history

Git Commands Cheat Sheet

Git Configuration

Command	Description
git config --global user.name <name>	Define the author name to be used for all commits by the current user
git config --global user.email <email>	Define the author email to be used for all commits by the current user
git config --global alias.<alias-name> <git-command>	Create shortcut for a Git command. E.g. alias glog "log --graph --oneline"
git config --system core.editor <editor>	Set text editor used by commands for all users on the machine
git config --global --edit	Open the global configuration file in a text editor for manual editing

Git Basics

Command	Description
git init <directory>	Create empty Git repo in specified directory. Run with no arguments to initialize the current directory as a git repository
git clone <repo>	Clone repo located at <repo> onto local machine. Original repo can be located on the local filesystem or on a remote machine via HTTP or SSH
git add <directory>	Stage all changes in <directory> for the next commit. Replace <directory> with a <file> to change a specific file
git commit -m "<message>"	Commit the staged snapshot, but instead of launching a text editor, use <message> as the commit message
git status	List which files are staged, unstaged, and untracked
git log	Display the entire commit history using the default format. For customization see additional options
git diff	Show unstaged changes between your index and working directory

Git Branches

Command	Description
git branch	List all of the branches in your repo. Add a <branch> argument to create a new branch with the name <branch>
git checkout -b <branch>	Create and check out a new branch named <branch>. Drop the -b flag to checkout an existing branch
git merge <branch>	Merge <branch> into the current branch

Git Log Options

Command	Description
git log --limit=<limit>	Limit number of commits by <limit>. E.g. "git log -5" will limit to 5 commits
git log --oneline	Condense each commit to a single line
git log -p	Display the full diff of each commit
git log --stat	Include which files were altered and the relative number of lines that were added or deleted from each of them
git log --author="<pattern>"	Search for commits by a particular author
git log --grep="<pattern>"	Search for commits with a commit message that matches <pattern>
git log <since>..<until>	Show commits that occur between <since> and <until>. Args can be a commit ID, branch name, HEAD, or any other kind of revision reference
git log -- <file>	Only display commits that have the specified file
git log --graph --decorate	--graph flag draws a text based graph of commits on left side of commit msgs. --decorate adds names of branches or tags of commits shown

Git Diff

Command	Description
git diff HEAD	Show difference between working directory and last commit
git diff --cached	Show difference between staged changes and last commit

Git Reset

Command	Description
git reset	Reset staging area to match most recent commit, but leave the working directory unchanged
git reset --hard	Reset staging area and working directory to match most recent commit and overwrites all changes in the working directory
git reset <commit>	Move the current branch tip backward to <commit>, reset the staging area to match, but leave the working directory alone
git reset --hard <commit>	Same as previous, but resets both the staging area & working directory to match. Deletes uncommitted changes, and all commits after <commit>

Git Rebase

Command	Description
git rebase -i <base>	Interactively rebase current branch onto <base>. Launches editor to enter commands for how each commit will be transferred to the new base

Git Pull

Command	Description
git pull --rebase <remote>	Fetch the remote's copy of current branch and rebases it into the local copy. Uses git rebase instead of merge to integrate the branches

Git Push

Command	Description
git push <remote> --force	Forces the git push even if it results in a non-fast-forward merge. Do not use the --force flag unless you're absolutely sure you know what you're doing
git push <remote> --all	Push all of your local branches to the specified remote
git push <remote> --tags	Tags aren't automatically pushed when you push a branch or use the --all flag. The --tags flag sends all of your local tags to the remote repo

Undoing Changes

Command	Description
git revert <commit>	Create new commit that undoes all of the changes made in <commit>, then apply it to the current branch
git reset <file>	Remove <file> from the staging area, but leave the working directory unchanged. This unstages a file without overwriting any changes
git clean -n	Shows which files would be removed from working directory. Use the -f flag in place of the -n flag to execute the clean

Rewriting Git History

Command	Description
git commit --amend	Replace the last commit with the staged changes and last commit combined. Use with nothing staged to edit the last commit's message
git rebase <base>	Rebase the current branch onto <base>. <base> can be a commit ID, branch name, a tag, or a relative reference to HEAD
git reflog	Show a log of changes to the local repository's HEAD. Add --relative-date flag to show date info or --all to show all refs

Remote Repositories

Command	Description
git remote add <name> <url>	Create a new connection to a remote repo. After adding a remote, you can use <name> as a shortcut for <url> in other commands
git fetch <remote> <branch>	Fetches a specific <branch> from the repo. Leave off <branch> to fetch all remote refs
git pull <remote>	Fetch the specified remote's copy of current branch and immediately merge it into the local copy
git push <remote> <branch>	Push the branch to <remote>, along with necessary commits and objects. Creates named branch in the remote repo if it doesn't exist