The document outlines a strategy for adopting Git with a focus on using branches and pull requests to enhance code delivery efficiency and quality. It emphasizes the importance of creating feature, bug, and hotfix branches off the master branch, regularly pushing changes, and using pull requests for code reviews and integration. Additionally, it discusses the role of continuous integration testing, highlighting tools and best practices that help streamline the process.

1. Switching to Git
Using branches and pull requests

2. What’s the goal?

3. Ship code that is ready for production often.
•
Build software that we are confident in
shipping
•
Ship code more often to address needs
•
Become better developers through industry
standard practices (with fewer bad habits)

4. Three kinds of tasks ...
•
Features (Add or change marketable
features)
•
Bugs (Fix issues reported by users and staff)
•
Hotfix (Fix very urgent issue with platform)

5. But how often has this happened?

6. Too much going on
Release
r100
Release
r101
r102
r103

7. What if we could ...
Release Release
r103
r100
Release Release
r102
r101

8. You could make this work with subversion
•
Create a branch for each task (feature, bug,
hotfix)
•
Reintegrate / release in whatever order is
needed
•
Slow process and lots of opportunity for
errors.

9. Turns out, we are not alone in having
this issue ...

10. ... and there’s already a (better/best)
practice

11. Most Important Slide™
•
Anything in the master branch is deployable
•
To work on something new, create a descriptively named branch off of master
(e.g. feature/new-oauth2-scopes)
•
Commit to that branch locally and regularly push your work to the same
named branch on the server
•
When you need feedback or help, or you think the branch is ready for
merging, open a pull request.
•
After someone else has reviewed and signed off on the feature, you can
merge it into master
•
Once it is merged and pushed to master, you can and should deploy
immediately
Stolen from http://scottchacon.com/2011/08/31/github-flow.html

12. What are git branches?
•
Files are blob objects in a database, stored
in .git/
•
A branch is really just a pointer to those objects
•
Switching branches is moving a pointer and
replacing the files (milliseconds)
•
Transparent to the file system
More on how it works at http://ftp.newartisans.com/pub/git.from.bottom.up.pdf

13. What is master?
•
The production-ready branch
•
Not the same thing as /trunk, other than it is
what all branches use as a parent
•
Git tags are created on code merged into
master, and those are then deployed to
production servers

14. Clone the repository
•
Grab a copy of the repository (only once)
$ cd ~/Sites/
$ git clone git@github.com/youruser/yourapp.git
Cloning into ‘yourapp’ ...

15. Create a branch
•
When you start a specific task, every time
$
*
$
$
*
git branch -l
master
git checkout -b bug/5012-fix-oauth
git branch -l
bug/5012-fix-oauth
master

16. Make changes
•
Do the work, commit it (and amend if
needed)
$ git branch -l
* bug/5012-fix-oauth
master
$ vim configuration/production.php
$ git add configuration/production.php
$ git commit -m “Fix OAuth secret for Twitter”
$ vim configuration/production.php
$ git add configuration/production.php
$ git commit --amend -m “Fix OAuth secret for Twitter, fixes
redmine #5012”

17. Push branch commits
•
Push to a named branch in the repository
$ git status
# On branch bug/5012-fix-oauth
nothing to commit, working directory clean
$ git push origin bug/5012-fix-oauth
Counting objects: 46, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (22/22), done.
Writing objects: 100% (24/24), 3.83 KiB | 0 bytes/s, done.
Total 24 (delta 17), reused 8 (delta 1)
To git@github.com:youruser/yourapp.git
06ff761..b3ea751 bug/5012-fix-oauth -> bug/5012-fix-oauth

18. Open a pull request
•
A pull request is used for integration or
feedback

19. Discuss pull request, merge accepted
•
Each pull request is a candidate for inclusion
in master, or at least a discussion about best
approach
•
Even “good” pull requests might have
multiple revisions
•
False starts happen – branches are “cheap”

20. Continuous integration testing
•
Pull requests will trigger a Jenkins build job and
add a contextual link to it within Github
•
A “build” is a snapshot of the repository at a
particular commit that is run through a testing
regimen
•
At minimum, committed files are run through
linters and the results are reported back on the
pull request via an API

21. Cleaning up
•
Once a branch is merged, it can be deleted
$ git branch --merged
bug/5012-fix-oauth
$ git branch --no-merge
* master
feature/top-secret
$ git branch -d bug/5012-fix-oauth
Deleted branch bug/5012-fix-oauth (was a705432).

22. Wait, what about forks?

23. Not necessary
Stolen from http://zachholman.com/talk/how-github-uses-github-to-build-github/

24. Pulling upstream changes

25. Get upstream changes
•
Pick up changes in the master branch
•
Merge from another fork/branch of changes
$ git pull origin master
remote: Counting objects: 18, done.
remote: Compressing objects: 100% (5/5), done.
remote: Total 11 (delta 8), reused 9 (delta 6)
Unpacking objects: 100% (11/11), done.
From git://github.com/youruser/yourapp
bfbb16f..75737c6 master
-> origin/master
Updating bfbb16f..75737c6
Fast-forward
src/unit/engine/PhpunitTestEngine.php | 2 +src/workflow/ArcanistUnitWorkflow.php | 3 ++2 files changed, 3 insertions(+), 2 deletions(-)

26. Get another branch
•
Fetch all branches, checkout from origin
$ git fetch origin
$ git checkout -b feature/acme origin/feature/acme
remote: Counting objects: 18, done.
remote: Compressing objects: 100% (5/5), done.
remote: Total 11 (delta 8), reused 9 (delta 6)
Unpacking objects: 100% (11/11), done.

27. A few tools to make the process easier

28. github/hub
•
Wrapper that shortens git commands for
GitHub

29. GitHub for Mac
•
Yes, there is a GUI, but learn to use the CLI

30. Quick recap
•
We’re switching to git to improve the code
review process and ship better code more often
•
All code changes are done through pull requests
and reviewed by appropriate developers
•
Continuous integration testing framework
through Jenkins works in tandem with pull
requests

31. That’s it.