/rebase-and-you

Rebase and YOU!

  • 10 min | what is a pull request, and why are we using it.
  • 25 min | walk thru of what the process looks like
  • 10 min | integration with codeship, and plans for the future
  • 15 min | questions

###What is a Pull Request?

  • PR's are a feature of GitHub, not GIT.
  • PR's are just a fancy diff between two branches.
  • PR's provide a venue for feedback and testing.
  • PR's can be a testing gate for CI systems (codeship, travis, jenkins, et cetera.)

###Why SHS-Web is using PRs

  • Master must be deployable.
  • Humans make mistakes.
  • Our team is growing, and code reviews are helpful.

###Rebasing. Why not just git pull?

Lets understand the problem first:

  • What does git pull actually do? pull = fetch + merge
    • fetch = update your tracking branches
    • merge = create a commit that blends two branches
      • GOTCHA: combine their history using timestamps!

This has some cofusing results. Especially when you're not done yet!

  • Your INCOMPLETE feture is now split into diff parts of the history by changes in master. Weak.
* e589d92 - feature apples! (6 minutes ago) <Dean Shelton>
*   fe21613 - Merge branch 'master' into feature (9 minutes ago) <Dean Shelton>
|\
| * b3891f9 - master-SUPER-IMPORTANT-THING-YOU-NEED (39 minutes ago) <GARY>
| * 6de3722 - master-cucumber! (39 minutes ago) <GARY>
* | d90186c - feature strawb (38 minutes ago) <Dean Shelton>
* | 3e72b4b - feature-bananas! (40 minutes ago) <Dean Shelton>
|/
* 57fc63c - initial commit! (41 minutes ago) <Dean Shelton>

###How does Rebasing solve this? git pull --rebase origin master would have given us this:

* e589d92 - (feature) feature apples! (6 minutes ago) <Dean Shelton>
|\
| * d90186c - feature strawb (38 minutes ago) <Dean Shelton>
| * 3e72b4b - feature-bananas! (40 minutes ago) <Dean Shelton>
* | b3891f9 - master-SUPER-IMPORTANT-THING-YOU-NEED (39 minutes ago) <GARY>
* | 6de3722 - master-cucumber! (39 minutes ago) <GARY>
|/
* 57fc63c - initial commit! (41 minutes ago) <Dean Shelton>

Note: All of your feature work is together! As it should be. You're not done, and may need to edit your commits before you're ready to merge.

Interactive Rebase git rebase -i HEAD~2 Rewind 2 commits back git rebase -i master Rewind since your current branched diverged from master.

###What does the process look like?

  1. Joe creates a local feature branch git checkout -b my_feature_branch_name`
  2. Joe runs npm run rebase to get up-to-date with origin master
  3. Joe does some work and makes a commit git add . && git commit -m 'changed something'
  4. Gary merges a pull request into master with super important changes
  5. Joe does a rebase git pull --rebase origin master (or npm run rebase)
  6. Joe resolves a merge conflict, and continues working.
  7. Joe makes 3 more commits
  8. Joe wants to PR his changes, but some of his commits before the rebase make the history confusing.
  9. Joes does an interactive rebase, git rebase -i master to combine two commits into one, and reword one of his commit messages.
  10. Joe pushes his code as a feature branch on origin git push origin my_feature_branch_name
  11. Joe opens his repo in github and creates the pull request.
  12. Joes tests are green, and he merges his code

Things that are now illegal

  • git push origin master
  • git merge or git pull without using --rebase