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Chapter 07: Git and GitHub

Mastering version control ensures source code integrity, streamlines team collaboration, provides clear audit trails, and enables automated deployment pipelines.

1. Fundamental Git Architecture & States

Git tracks file snapshots across three primary local areas before synchronizing with a remote repository.

┌─────────────────────────┐      git add       ┌─────────────────────────┐
│    Working Directory    │ ─────────────────> │      Staging Area       │
│  (Unstaged modifications)│                    │  (Index / Prepared)     │
└─────────────────────────┘                    └────────────┬────────────┘
             ▲                                              │
             │                                              │ git commit
             │              git checkout / switch           │
             └──────────────────────────────────────────────┼────────────┐
                                                            ▼            │
                                               ┌─────────────────────────┴┐
                                               │    Local Repository      │
                                               │  (.git directory / HEAD) │
                                               └────────────┬─────────────┘
                                                            │
                                                            │ git push
                                                            ▼
                                               ┌──────────────────────────┐
                                               │    Remote Repository     │
                                               │   (GitHub / GitLab)      │
                                               └──────────────────────────┘

2. Branching Strategies: Trunk-Based vs. GitFlow

Choosing the right branching strategy depends on team velocity, delivery cadence, and release models.

Trunk-Based Development (Recommended for Modern SaaS / CI/CD)

  main ───●───────●───────●───────●───────●─── (Continuous Integration)
           \     /       \     /
  feature   └──●─┘        └──●─┘
Feature Trunk-Based Development GitFlow
Branch Lifetime Short-lived (hours to days) Long-lived (weeks to months)
Complexity Low High (main, develop, feature, release, hotfix)
Merge Friction Minimal (Frequent small merges) High (Infrequent massive merges)
Best For Continuous Delivery, SaaS, Microservices Scheduled releases, Mobile apps, On-premise software

3. Merge vs. Rebase & Conflict Resolution

Merging vs. Rebasing

  • git merge: Creates a non-destructive merge commit combining history. Preserves exact historical chronology but can result in messy commit graphs.
  • git rebase: Replays local commits on top of the target branch's latest HEAD. Produces a clean, linear project history.
Git Merge:                               Git Rebase:
      A---B---C  (feature)                     A'--B'--C' (feature)
     /                                        /
D---E---F---G    (main)                  D---E---F---G    (main)

Golden Rule of Rebasing: Never rebase branches that have already been pushed to a public or shared repository.

Interactive Rebase Command Checklist

# Squash or edit the last 3 commits before merging a pull request
git rebase -i HEAD~3
  • pick: Keep the commit.
  • squash (s): Meld the commit into the previous commit.
  • reword (r): Keep commit content but rewrite the commit message.

4. Conventional Commits Standard

Standardizing commit messages enables automated semantic versioning (semver), changelog generation, and automated release notes.

Commit Format

<type>(<scope>): <short description>

[optional body]

[optional footer]

Common Commit Types

  • feat: A new feature for the user.
  • fix: A bug fix.
  • docs: Documentation changes only.
  • style: Code style/formatting changes (no logic change).
  • refactor: Code change that neither fixes a bug nor adds a feature.
  • test: Adding or correcting tests.
  • chore: Maintenance, dependencies, or build tool updates.

Example

feat(auth): add JWT refresh token rotation mechanism

Implements token rotation on every refresh request to prevent replay attacks.
Invalidates compromised refresh tokens automatically upon reuse.

Closes #104