This document summarizes a software company's migration from Mercurial to Git for source control and their new workflow using Git. They implemented Vincent Driessen's branching model with long-running branches for master, staging, and development. Developers work in their own forks, rebase regularly, and submit pull requests to integrators for review and merging into staging or development. This standardized process aims to reduce merge conflicts and enable predictable integration and deployment between branches.

1. 40 Square’s GIT Workflow
Who Am I?
Lead developer in 40 square software
First Love: 6 years in Java (omfg what was I thinking)
Ex-GF: PHP hobbyist turned full time engineer
Wife: Node.JS, and Javascript in general
Twitter: @roguejs
This will be a warp speed presentation!

2. Mercurial vs Git
We used fogbugz + kiln initially
Started off with feature branches
Merging conflicts took forever
REAL REASON: Bad practices
HIDDEN REASON: Fogbugz is expensive...

3. Other annoyances
No dry runs
Difficult to do code review
No cherry-picking
Bad planning and structure
Branching is expensive?

4. Our Deployment Process
LDC
Dev C1 LDC
B1
push hg
pull CDC
Dev
repo B
Branches CDC
Dev - qa C
- master

5. Deployment Problems
Accidentally merge into master? RED ALERT
QA testing on old code
Dev: “Is my feature merged yet?”
Lead: “Hold on, I’m fixing conflict #13285582309583”
live
dev1
invalidates previous test
dev2

6. Why Git?
Because github is sexy
Actually, because it’s cheaper than Kiln
Why not bitbucket?
Because github is sexy, and because I said so
Actually, because github still is cheaper (repo vs users)
Git has more options for branching and merging

7. Our Goals
Have a staging server that is a clone of live server
Abstract devs from live server
No more “it’s just one line of code, can I push to live
directly?”
Rapid deployment and lesser merge conflicts
Build better practices

8. Vincent Driessen Model
40 square style
Long Running Branches:
master - live servers
staging - last line of defense
devel - weekly deployments
Distributed blessed repo model
Blessed repo managed by integrators
Each dev gets own fork

9. Forking Model & Policy
Your own fork is your own responsibility
Feel free to force update your own fork
Rebase before sending pull requests

10. Typical Workflow (dev)
Dev starts work on an issue in Pivotal
Determine what kind of issue:
P1- branch off from staging
Bugs & Features - branch off from devel
Pull upstream often and rebase on upstream
Rebase again before sending pull request

11. Typical Workflow (dev)
git fetch --all (git version 1.7.x)
git branch --track up-devel upstream/devel
git branch P1-1305 up-devel
git fetch upstream devel
git checkout up-devel
git merge upstream/devel
git checkout P1-1305
git rebase up-devel

12. Typical Workflow (integrator)
Integrator receives pull request
Create a new branch in blessed repo
Pull update into that branch
Review code
Merge into staging/devel

13. Typical Workflow (Integrator)
git branch soggie-P1-1305 devel
git checkout soggie-P1-1305
git pull soggie P1-1305
git rebase devel
git checkout devel
git merge soggie-P1-1305
git push origin devel:devel

14. Overall Workflow
LDC
Dev C1 LDC
git
B1
repo
push
git git
pull CDC
Dev
repo integrate repo B
git
CDC
repo
Dev C

15. Timeline View
Black line = master
Blue line = staging
Green line = dev

16. Devel branch deployment
Every MONDAY, merge to staging
Once testing completes, tag and merge to master
If testing fails, all bug fixes are designated as P1
Bug fixes for release candidate is merged into staging
master
fail
staging
fix
devel

17. Staging branch deployment
Merge to staging and test
Once QA approves it, merge to master AND devel
Policy: Only one commit allowed to dangle
master
never!!!
staging
devel

18. Policies
Do NOT force update blessed repo
I will hunt you down, and kill you
Always rebase before sending pull request
If P1, branch off staging. Otherwise, branch off devel
Manage pull requests NOW
No dangling commits on staging

19. Benefits
Established workflow = peaceful work environment
Predictable integration & deployment
Conflicts = dev responsibility instead of integrator’s
Can dick around with own repo without killing blessed
repo
No more unpredictable testing environment

20. More Information
A successful branching model
http://nvie.com/posts/a-successful-git-branching-
model/
Git
http://git-scm.com/
Github
http://github.com/
Git video tutorials
http://gitcasts.com/