Skip to content

Latest commit

 

History

History
165 lines (109 loc) · 4.3 KB

README.md

File metadata and controls

165 lines (109 loc) · 4.3 KB
Raw

Presentation URL: https://gitpitch.com/devopsacademyau/academy?p=classes/01class/git/

Let's Get Started with Git

Versioning: The "old way"

  • Pessimistic locking, code duplication
    • Local versioning -> Copy and paste (Let's duplicate!)
    • Version overwriting (Who deleted my version!?)
    • Locked file (Can you please release file customers.xls, please!?)
  • Are there other problems?

What is Git?

  • Created by Linus Torvalds in 2005 for development of the Linux kernel
  • Git is a distributed VCS
  • Centralized vs Distributed VCS?
  • Optimistic vs Pessimistic locking?

IMAGE

Centralised vs Distributed VCS

  • Centralised:
    • Centralised master version
    • Code Check outs (one developer is allowed to work on that part of the code at any one time.)
    • Locking controlled by the server
    • Release records version numbers of all elements
  • Distributed:
    • Entire history of changes cloned by developers
    • No locking
    • Changes modify history (append or rewrite)
    • Release is a history of changes

Optimistic Locking

IMAGE

So, how git achieves optimistic locking so developers can work in parallel in the same file?

Git Storage

IMAGE

Git Main Commands

  • start a working area (see also: git help tutorial)

    • clone Clone a repository into a new directory
    • init Create an empty Git repository or reinitialize an existing one

  • work on the current change (see also: git help everyday)

    • add Add file contents to the index
    • mv Move or rename a file, a directory, or a symlink
    • reset Reset current HEAD to the specified state
    • rm Remove files from the working tree and from the index

  • examine the history and state (see also: git help revisions)

    • bisect Use binary search to find the commit that introduced a bug
    • grep Print lines matching a pattern
    • log Show commit logs
    • show Show various types of objects
    • status Show the working tree status

Git Main Commands (more)

  • grow, mark and tweak your common history

    • branch List, create, or delete branches
    • checkout Switch branches or restore working tree files
    • commit Record changes to the repository
    • diff Show changes between commits, commit and working tree, etc
    • merge Join two or more development histories together
    • rebase Reapply commits on top of another base tip
    • tag Create, list, delete or verify a tag object signed with GPG

  • collaborate (see also: git help workflows)

    • fetch Download objects and refs from another repository
    • pull Fetch from and integrate with another repository or a local branch
    • push Update remote refs along with associated objects

Let's do it together

Let's add a folder to hold exercises for classes

  1. Check README.md in the root for instructions.
  2. Add, commit and push it to your remote dev branch 🎉
  3. Create a Pull Request (PR)

Checking in code can get complex (quickly!)

IMAGE

How can we have a standard approach to work as one team?

A solution: Trunk based development

Short lived branches simplify a lot of things! https://trunkbaseddevelopment.com/

See also GitFlow

IMAGE

Merging vs Rebasing

git checkout feature git merge master IMAGE

git checkout feature git rebase master IMAGE

What is the problem of re-writing the history with git rebase?

Let's do it together - Exercise

Merging and Rebasing

  1. Access https://learngitbranching.js.org/
  2. Merging exercise:
    1. type level intro3
  3. Rebasing exercise:
    1. type level intro4

OMG, I don't know what I did!

https://ohshitgit.com/

References

  1. https://martinfowler.com/eaaCatalog/optimisticOfflineLock.html
  2. https://www.teamstudio.com/blog/distributed-vs-centralized-version-control-systems-for-lotus-notes
  3. https://www.atlassian.com/git/tutorials/merging-vs-rebasing