Git and GitHub Fundamentals

Overview of Git/GitHub

Working without Version Control:

Working with Version Control:

Git

• Free and open source software
• Distributed VCS
• Accessible anywhere in the world
• One of the most common version control systems available
• Can also version control images, documents, etc.

Short Glossary of Terms

SSH protocol – A method for secure remote login from one computer to another.

Repository – The folders of your projects that are set up for version control.

Fork – The process you use to request that someone reviews and approves your changes before they become final.

Working directory – A directory on your file system, including its files and subdirectories, that is associated with a git repository.

Introduction to GitHub

Background of Git:

• Large software projects need a way to track and control source code updates
• Linux needs automated source-version control
• Key characteristics include:
  • Strong support for non-linear development
  • Distributed development
  • Compatibility with existing systems and protocols
  • Efficient handling of large projects
  • Cryptographic authentication of history
  • Pluggable merge strategies

Git Repository Model:

• What is special about the Git Repository model?

  • Distributed VCS
  • Tracks source code
  • Coordinates among programmers
    • Tracks changes
    • Supports non-linear workflows

• Created in 2005 by Linus Torvalds

  What is Git?

• Git is a distributed VCS

  • Tracks changes to content
  • Provides a central point for collaboration

• Git allows for centralized administration

  • Teams have controlled access scope
  • The main branch should always correspond to deployable code

• IBM Cloud is built around open-source tools including Git repositories

GitHub

• GitHub is an online hosting service for Git repositories
  • Hosted by a subsidiary of Microsoft
  • Offers free, professional, and enterprise accounts
  • Till 2022, it had over 100M repos
  • What is a Repository?
    • A data structure for storing documents including application source code
    • A repository can track and maintain version-control

GitLab

GitLab is:

• A DevOps platform, delivered as a single application

• Provides access to Git repositories

• Provides source code management

  GitLab enables developers to:

• Collaborate

• Work from a local copy

• Branch and merge code

• Streamline testing and delivery with CI/CD

Using Git Commands and Managing GitHub Projects

GitHub Workflows with Branches and Git Commands

GitHub Branches

What are branches?

• Branches store all files in GitHub
• The master branch stores the deployable code
• Create a new branch for planned changes

Merging Branches:

• Start with a common base
• The code is branched while new features are developed
• Both branches are undergoing changes
• When the two streams of work are ready to merge, each branch’s code is identified as a tip and the two tips are merged into a third, combined branch

What is a Pull Request?

• A PR makes the proposed (committed) changes available for others to review and use

• A pull can follow any commits, even if code is unfinished

• PRs can target specific users

• GitHub automatically makes a PR if you make a change on a branch you don’t own

• Log files record the approval of the merge

  Merging into the Master/Main Branch

• The master branch should be the only deployed code

• Developers can change source files in a branch, but the changes are not released until

  • They are committed
  • A Pull command is issued
  • The code is reviewed and approved
  • The approved code is merged back into the master code

Cloning and Forking GitHub Projects

• Powerful tools include forking and cloning a repository

• Cloning creates a copy of a repository on your local machine

• Cloned copies can sync between locations

• Forking modifies or extends a project

  Remote Repositories:

• Remote repos are stored elsewhere

• Push, pull, and fetch data to share work

• Origin refers to your fork

• Upstream refers to the original work

Forking a Project

• Forking
  • Takes a copy of a GitHub repository to use it as the base for a new project
  • Submit changes back to the original repository
• Independently make changes to a project
  • Submit a PR to the original project owner
  • Owner decides whether to accept updates
• Keep a copy of the license file
  • Often a legal requirement
  • Good practice

Syncing a Fork of a Project:

To keep a fork in sync with the original work from a local clone:

• Create a local clone of the project

• Configure Git to sync the fork

  • Open terminal and change to the directory containing the clone
  • To access the remote repository, type git remote -v
  • Type git remote add upstream <clone repo url>
  • To see the changes, type git remote -v

  Commands for Managing Forks:

  To grab upstream branches

git fetch upstream

To merge changes into the master branch

git merge upstream/master

Managing GitHub Projects

GitHub Developer:

A Developer communicates with others using these commands:

• git-clone from the upstream to prime the local repository
• git-pull and git-fetch from “origin” to keep-up-to-date with the upstream
• git-push to shared repository, if you adopt CVS style shared repository workflow
• git-format-patch to prepare email submission
• git-send-email to send your email submission without corruption by your MUA (Mail User Agent)
• git-request-pull to create a summary of changes for your upstream to pull

GitHub Integrator:

An integrator

• Receives changes made by others

• Reviews and responds to PRs

• Publishes the result for others to use

  Integrators use the following commands:

• git-am to apply patches emailed in from your contributors

• git-pull to merge from your trusted lieutenants

• git-format-patch to prepare and send suggested alternatives to contributors

• git-revert to undo botched commits

• git-push to publish the bleeding edge

GitHub Repository Administrator

A Repository Administrator sets up and maintains access to the repository by developers

• git-daemon to allow anonymous download from repository
• git-shell can be used as a restricted login shell for shared central repository users
• git-http-backend provides a server-side implementation of Git-over-HTTP (Smart HTTP) allowing both fetch and push services
• gitweb provides a web front-end to Git repositories, which can be set-up using the git-instaweb script