Git Flow

transcript

GIT Flowfacebook.com/mfernandes.fernando

Friday, August 10, 12

Why GIT?

Why GIT?• Distributed

• A clone of the *entire* repository (history, tags) in each dev machine

• Code on the road! You are the repository. Multiple backups.

• Branching model

• Easy: git checkout -b <someFeature>

• Branching model

• Convenient: Create, try out an idea, commit, switch back, merge or discard.

• Branching model

• Small and Fast

• Branching model

• Small and Fast

• Written in C (which reduces runtime overhead associated with high-level languages)

• Branching model

• Small and Fast

• Written in C (which reduces runtime overhead associated with high-level languages)

• Built to work on the Linux kernel (it has had to effectively handle large repositories from day one)

Benchmarks

Staging (or index) Area

Free and Open Source

• GPLv2

• Free, forever

• GPLv2

• Free, forever

• Download, inspect and modify GIT source

Workflows

• getBestWorkflow()

Workflows

• NPE

Workflows

• NPE

• ANY!

Subversion-Style

Integration Manager

Dictator and Lieutenants

gitflow

gitflow• GIT abstraction

• Just a bunch of scripts

• Greatly inspired by existing models

• Main branches:

• master

• Main branches:

• master

• develop

• Main branches:

• master

• develop

• Support branches:

• Main branches:

• master

• develop

• feature

• Main branches:

• master

• develop

• feature

• release

• Main branches:

• master

• develop

• feature

• release

• hotfix

gitflowThe BIG picture

gitflow: Main branches

gitflow: Main branches• origin/master is

where the source code of HEAD always reflects a production-ready state.

gitflow: Main branches• origin/master is

where the source code of HEAD always reflects a production-ready state.

• origin/develop is where the source code of HEAD always reflects a state with the latest delivered development changes for the next release.

gitflow: Supporting branches - FEATURE

• Definition: used to develop new features for the upcoming or a distant future release.

• Tipically exist in developer repos only, NOT IN ORIGIN

• Branch off from: DEVELOP

• Must merge back into: DEVELOP

• Branch naming convention:

• <devName>-* (fernando-gallery)

• (!) Not allowed: master, develop, release-* or hotfix-*

gitflow: Supporting branches - RELEASE

gitflow: Supporting branches - RELEASE• Definition: support preparation of a new

production release. Allow for MINOR bug fixes and preparing meta-data for a release (version number, build dates, etc.)

• When? develop (almost) reflect the desired state of the new release. All planned features were implemented.

• Must merge back into: DEVELOP and MASTER

• <release>-* (release-1.0)Friday, August 10, 12

gitflow: Supporting branches - HOTFIX

gitflow: Supporting branches - HOTFIX• Definition: arise from the necessity to

act immediately upon an undesired state of a live production version. CRITICAL bugs!

• Branched off from the corresponding tag on the master branch that marks the production version.

• Branch off from: MASTER

• hotfix-* (hotfix-1.2.1)Friday, August 10, 12

(again)

Feature. How?

Feature. How?• git checkout -b myfeature develop

• Switched to a new branch “myfeature”

• Do some work. When done...

• git checkout develop

• Switched to branch ‘develop’

• git merge --no-ff myfeature

• Updating ea1b92a...

• git branch -d myfeature

• Deleted branch myfeature

• git push origin develop

--no-ff

--no-ff• This flags causes the merge to

always create a new commit object.

• Without it, it’s impossible to see from Git history which of the commit objects together have implemented a feature.

• You will have to read all the log messages manually.

• Compare:

Create a release. How?

• git checkout -b release-1.2 develop

• Switched to a new branch “release-1.2”

• Manually modify the README, RELEASE NOTES, etc.

• git commit -a -m “Bumped to version 1.2”

• [release-1.2 74d9424] Bumped to version 1.2

• 1 files changed, 1 insertions(+), 1 deletions(-)

Finish a release. How?

Finish a release. How?• When the release branch is ready to become a real release, it is merged into master (every commit on

master is a new release by definition) and the commit is tagged for easy future reference to this historical version. Finally it’s merged back into develop, so future releases contain the bug fixes.

• git checkout master

• Switched to branch “master”

• git merge --no-ff release-1.2

• Merge made by recursive. (Summary of changes)

• To keep the changes made in the release branch, we need to merge those back into develop.

• git tag -a 1.2 // Can use -s or -u <key> to sign cryptographically

• Switched to branch “develop”

• It may lead to a merge conflict. Fix it and commit.

• Now we are really done and the release branch may be removed, since we don’t need it anymore.

• git branch -d release-1.2

• Deleted branch release-1.2 (was ff452fe)

Create a hotfix. How?

Create a hotfix. How?• git checkout -b hotfix-1.2.1 master

• Switched to a new branch “hotfix-1.2.1”

• git commit -a -m “Bumped to version 1.2.1”

• [hotfix-1.2.1 416e61] Bumped to version 1.2.1

• Fix the bug and commit the fix.

• git commit -m “Fixed severe production problem”

• [hotfix-1.2.1 416e61] Fixed severe production problem.

Finish a hotfix. How?

Finish a hotfix. How?• git checkout master

• git merge --no-ff hotfix-1.2.1

• git tag -a 1.2.1 // Again, this can be done cryptographically

• Include the bugfix in develop too. The exception: if there is a release branch, the hotfix changes need to be merge into that release branch instead of develop.

• Finally remove the temporary branch

• git branch -d hotfix-1.2.1

• Deleted branch hotfix-1.2.1 (was abbe5d6)

It was just a flesh wound, right?

That’s it!

Referenceshttp://nvie.com/posts/a-successful-git-branching-model/

http://learn.github.com/p/tagging.html

http://reinh.com/blog/2009/03/02/a-git-workflow-for-agile-teams.html

http://stackoverflow.com/questions/1616957/how-do-you-roll-back-reset-a-git-repository-to-a-particular-commit

http://stackoverflow.com/questions/1457103/what-is-the-difference-between-a-tag-and-a-branch-in-git

Thanks!

Git Flow

Technology