Source Code Management

• Two kinds of code

  • Source code - written in high-level language

  • Binaries - compiled from the source code

• Provided a central location to store your code, version changes and allow multiple developers to collaborate on the same source code.

• SCM tools - Git, subversion , mercurial and cvs

Git

• Initialize the git repo

•     $ mkdir repo-name && cd repo-name/
      $ git init 
      Initialized empty Git repository in ~/repo-name/.git/
  

• Staging code changes

  • add remove from staging area

    • git add

    • git restore

•     $ touch file1
      $ git status
      On branch master
      No commits yet
      Untracked files: (use "git add <file>..." to include in what will be committed)
      file1
      nothing added to commit but untracked files present (use "git add" to track)
      $ git add file1
      $ git status
      On branch master
      No commits yet
      Changes to be committed: (use "git rm --cached <file>..." to unstage)
      new file: file1
      $ git commit -m "First commit"
      [master (root-commit) cecfb61] My first commit
      1 file changed, 0 insertions(+), 0 deletions(-)
      create mode 100644 file1
  

• Commit History

  • git log

• Differences in commit

  • git diff <first-commit-id> <second-commit-id>

• Amending last commit

  • git commit --amend

• Connecting the local repository to the remote repository

  • git remote add origin git@github.com:<username>/<repo-name>.git

• Pushing changes from the local repository to the remote repository

  • git push -u origin master

• Pulling and rebasing code

  • pulling - downloading changes

  • rebasing - applying changes on top of latest remote commit

  • git pull --rebase

• Merge conflict

• Create Git Branch

  • git branch feature/feature1

• Switch to branch

  • git branch feature/feature1

• Pushing to branch

  • git push -u origin feature/feature1

• Pull requests

  • A pull request is a request for merging a source branch to a base branch.

GitOps

• Implementing DevOps so that Git is single source of truth

• Focuses on Git to manage infrastructure provisioning and application software deployments.

• Why GitOps?

  • Deploys software quickly.

  • Provides faster recovery from errors.

  • Better credential management

  • Deployments are self-documenting.

  • Promotes shared ownership and knowledge.

• Branching strategies and GitOps workflow

  • Two kind of repository

    • Application repository

    • Environment repository

  • Deployment models

    • Push model

      • Any changes in git repo pushed to environment

      • Jenkins, CircleCI, or Travis CI + Terraform and ansible is used.

      • Need to store credentials within tool.

      • Not recommended

    • Pull model

      • agent-based deployment model

      • Agent monitors changes in git repo and applies it when needed.

      • Advantage - it monitors and reacts to environment changes alongside repo changes.

      • No need to store credential in tool as operators is within environment.

    • Branching strategies - Gitflow, GitHub flow.