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 Preview
    • rel_1.1 Preview
  • Now lets make a change in rel_1.0 and commit the changes to local repo Preview
  • 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 Preview
  • Lets make changes in master branch and commit those changes and also do some changes on rel_1.0 branch Preview Preview
  • Now we need to merge the changes from rel_1.0 to master
    • Merges might lead to conflicts and that needs to be resolved Preview Preview
  • 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 Preview

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

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 Preview
  • 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 Preview
    • 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> Preview Preview Preview
    • Lets try to push all the branches to remote repo Preview Preview
  • How to get the copy of the code from existing remote repository
    • This operation is referred as clone. Preview Preview
    • Now lets checkout to rel_1.1 Preview
  • To push the changes to remote repository, we need permissions Preview

Next Steps

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

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