DevOps Classsroom Series – 07/Feb/2021

Git Contd..

Scenario: Understanding Branches

• There will be many cases where parallel tracks of development will happpen on your projects
• Git branches enable you to create parallel tracks of development. In Git there is already a default branch which is referred as master
• Now lets create two more branches
  • rel_1.0
  • rel_1.1
• Now lets make a change in rel_1.0 and commit the changes to local repo
• Now lets make a change in rel_1.1 and commit the changes to local repo
• Branch will point to the latest commit on that branch and head will be pointing towards branch which points to latest commit
• Now we need changes of rel_1.0 branch to be in master.
  • Fast forward merge
• Lets make changes in master branch and commit those changes and also do some changes on rel_1.0 branch
• Now we need to merge the changes from rel_1.0 to master
  • Merges might lead to conflicts and that needs to be resolved
• Git Rebase
  • Refer Here for documenation
  • Lets rebase master onto rel_1.1

  git checkout rel_1.1
  git rebase master
  # fix merge conflicts 
  # add the changes usign git add
  # then continue the rebase git rebase --continue
  

  
• In git if you want to pick certain commits and add it to the branch then that is referred as cherry-picking
• Now lets create two branches from master
  • rel_1.2
  • rel_1.3
• Refer Here for cherry-pick documentation
• Now we have understood three ways bringing changes from one branch to other
  • merge
  • rebase
  • cherry-pick

How Git Works

• To understand how git works, we need to know about

  • Hashing (SHA1):
    • This is transformation of string of characters into a shorted fixed length value
    • Two text with same value will have same hash

• Git can be reffered as a stupid content tracker.

• In Git every commit id is generated by calculating hash of

  • Changes
  • Author
  • Date time
  • Message

• Every commit will have a parent commit

• In Git Commit tree stands for folder and binary large object (blob) stands for file

Fourth Area of git

• Fourth area of git is referred as remote repository, which is used to collobarate work done by multiple developers in an orginization
• Git remote repository contains the same .git folder and in addition to that it will have
  • connectivity options (for developers to connect)
• To have this on git remote repository some daemon will be running.
• There are many ways to configure git remote repository
  • We can host git remote repository on some shared folder in your organization
  • We can use some git remote repository softwares
    • Gitolite
    • GitLab
  • We can use some hosted git remote repository options
    • GitHub
    • BitBucket Cloud
    • GitLab
    • Azure Source repos
    • AWS Code Commit
• We can have a local repository which is connected to multiple remote repositories
• Just like master was a default branch, the default remote repository also will have a name origin
• So now lets create a new repository in GitHub and send all the changes which we have done in the class to that repository
  • Add remote repository to local repo
  • Sending the changes from local repo to remote repo is referred as push and the command for pushing is git push <name-of-remote> <name-of-branch>
  • Lets try to push all the branches to remote repo
• How to get the copy of the code from existing remote repository
  • This operation is referred as clone.
  • Now lets checkout to rel_1.1
• To push the changes to remote repository, we need permissions

Next Steps

• Understanding multiple users workflow
• Understanding recieving latest changes from remote repository
• Understanding git tags
• How to make changes to the existing commits