real world git workflows - eclipsecon europe 2013

Real World Workflows

Nicola PaolucciDeveloper Advocate / Git Evangelist

@durdndurdn.comI come out nice in pictures, I know :-).

Cheap local branchingFull local history

Speed

Staging area

prominent in Open Source

Huge community

You heard has

Feature based workflow

10x the speed of svn

Distributedcryptographic integrity

ground breaking paradigm is ground breaking

Workflow building blocks

rebasepowerful merging

fork

clone

cheap branching

distributed

RELEASECan we fix a bug for the

upcoming?

FEATUREIs the code for that

complete?

BUILDCan we

the current code ?

REVIEWEDHas everybody

the code for this feature ?

HOTFIXCan we do a fast

for the current release?

What we’ll cover:

1

What we’ll cover:

Branching models

Practices & Decisions

1

2

What we’ll cover:

Branching models


1

2

What we’ll cover:

Branching models

Tooling & Automation3


1

2

What we’ll cover:

Branching models


4 Continuous Integration

Which branching model?

Which branching model?1

Two common Branching Models

1 Continuous Delivery


Product Releases

1 Continuous Delivery

2


for Continuous Delivery

1.1 for Continuous Delivery

Tim

emaster/

productionstagingfeature

Tim

emaster/


master is in production

Tim

emaster/



staging is the next version

Tim

emaster/




new features off staging

with branch names like: username/ISSUE-KEY-summary

Tim

emaster/






PR

Tim

emaster/






promoted from staging, can receive hotfixes

PR

Tim

emaster/






promoted from staging, can receive hotfixes

Hotfix

PR

for Product Releases

for Product Releases1.2

One Central Repository1


One Branch per Feature2

Tim

emasterfeature

branches

PRJ-

123-

desc

ript

ion


One Branch per Feature

One Branch per Bugfix

2

3

Tim

emasterbugfix

branch

PRJ-

123-

bug-

desc

ript

ion

Tim

emasterrelease

branch

PRJ-

345-

bug-

desc

ript

ion

bugfix

2.2

Release Branches4

Tim

emasterrelease

branch

PRJ-

345-

bug-

desc

ript

ion

bugfix

2.2

Release Branches4

Long running

Tim

emasterrelease

branch

PRJ-

345-

bug-

desc

ript

ion

bugfix

2.2

Release Branches4

master is alpha / RC5

Long running

Tim

emasterrelease

branch

PRJ-

345-

bug-

desc

ript

ion

bugfix

2.2

Automatic merges for the win!

PRJ-

345-

bug-

desc

ript

ion

Tim

e

release branch

master

2.2

release branch

bugfix

2.1

PRJ-

345-

bug-

desc

ript

ion

Tim

e

release branch

master

2.2

release branch

bugfix

2.1

Automatic MERGES!

Placeholder for changes you DON’T want to merge!

release branch

2.2

release branch

2.1

2.2.1

release branch

2.2

release branch

2.1

2.1.4

2.2.1

release branch

2.2

release branch

2.1

2.1.4

2.2.1

2.1.5-SNAPSHOT

release branch

2.2

release branch

2.1

2.1.4

2.2.1

We don’t want to merge the 2.1.x version!

2.1.5-SNAPSHOT

release branch

2.2

release branch

2.1

2.1.4

2.2.1

We don’t want to merge the 2.1.x version!

2.1.5-SNAPSHOT

What can we do here?

git merge

git mergegit merge --strategy= resolve

git merge --strategy= recursive

git merge --strategy=

git merge --strategy= ours

stable branch

2.2

stable branch

2.1

2.1.4

2.2.1

2.1.5-SNAPSHOT

stable branch

2.2

stable branch

2.1

2.1.4

2.2.1

2.1.5-SNAPSHOT

$> git checkout stable-2.2$> git merge -s ours stable-2.1

stable branch

2.2

stable branch

2.1

2.1.4

2.2.1

2.1.5-SNAPSHOT

merge commit, content discarded$> git checkout stable-2.2

$> git merge -s ours stable-2.1

Deep breath, it’s really simple

The merge protocolThe secret sauce

Release branch


When a branch is: Change flows from branch to baseline:

Change flows from baseline to branch:

More stable than its baseline

Less stable than its baseline

Continuously Never

When code complete Continuously

Release branch






Continuously Never


Release branch

Release branch






Continuously Never


Release branch

Release branch

Feature branches






Continuously Never


Release branch

Release branch

Feature branchesCredit: Laura Wingerd - The Flow of change


Release branch

Release Branch

Master


Release branch

Release Branch

Master

Mergecontinuously


Release branch

Release Branch

Master

Mergecontinuously

Never merge!


Release branch

Release Branch

Master

Mergecontinuously

Backport single changes using git cherry-pick

Never merge!

Practices & Decisions2

turbo boost!

What is a Pull Request?

Hey I have some code I want to merge here,

take a look?

Low friction collaboration

Pull Request

I have some code here!

Can I merge it here?

Does a debate even exist?

Merge vs Rebase

MER

GE REBA

SE

What is a Rebase?

master

feature

What is a Rebase?Merge commit

master

feature

master

feature

What is a Rebase?Merge commit

master

feature

Merge as team policy

Traceability1


Traceability1

At a cost: readability2


Traceability1


3


bisect debugging is harder

Traceability1


3


bisect debugging is harder

with no fast-forwards

Rebase as team policy [1]

History flat and clean1



Delicate with Pull Requests2



Delicate with Pull Requests

Dangerous for unexperienced

2

3


Re-resolve similar conflicts4



Requires often a force push5



Requires often a force push

Loses context for feature

5

6


Rebase as a local cleanup

Do it1


Do it1


git rebase --interactive

Do it1

Do it2



Do it1

Do it

Do it!!!!!!

2

3



Recommendation?

If team unfamiliar, don’t rebase1

Recommendation?


Encourage rebase as cleanup2

Recommendation?

and proper ecology


Encourage rebase as cleanup

Choose clean or traceable

2

3

Recommendation?

and proper ecology

Recommendation?

Don’t fear the Merge! Use it!4

Recommendation?


Recommendation?Explicit merges into the mainline


Recommendation?

git log --first-parent

Explicit merges into the mainline


May rebase feature branches5

Recommendation?





Recommendation?


To update the feature branch




Recommendation?




After review!


May rebase feature branches

Work with the tool!

5

6

Recommendation?




After review!


May rebase feature branches

Work with the tool!

5

6

Recommendation?


Trying to strive for a linearized history is less useful than you think



After review!

Single Repositoryvs

Remote Forks

Every one has their remote repository

With Forks

Every one has their remote repository

With Forks

Full remote copy,each has one Integrator, Gatekeeper,

Tech Lead, etc.

Pros of a Single Repo

Complete visibility1

Pros of a Single Repo


Pros of a Single RepoAll feature branches available


No per Dev remotes required2



No per Dev remotes required

KISS

2

3


Forks Are Great too BTW

FORKING IN THE

ENTERPRISE

FORKING IN

ENTERPRISE5 Reasons for...

FORKING IN

ENTERPRISE

REASON 1

Great for customizing libraries

FORKING IN

ENTERPRISE

REASON 1

Great for customizing librariesand still get bug fixes

REASON 2

Great for innovation spikes

FORKING IN

ENTERPRISE

REASON 2

Great for innovation spikesand maybe add it later

FORKING IN

ENTERPRISE

REASON 3

Protecting your components

FORKING IN

ENTERPRISE

REASON 3

Protecting your components

but still be open for changes

FORKING IN

ENTERPRISE

REASON 4

Reduce the noise

FORKING IN

ENTERPRISE

REASON 4

Reduce the noise

and keep the overview for huge projects

FORKING IN

ENTERPRISE

REASON 5

Interaction with Contractors & Interns

FORKING IN

ENTERPRISE

REASON 5

Interaction with Contractors & Interns

protect your sources

FORKING IN

ENTERPRISE

Tooling & Automation

Hooks are little scripts you can place in

the `$GIT_DIR/hooks` directory to trigger

action at certain points.

– githooks Documentation

”“

Pre Post

Local Remote

Local Remotepre-receiveupdatepost-receivepost-update

pre-/post-applypatchpre-/post-commit

pre-rebasepost-checkout

post-mergepre-push

Code Quality via pre-commit hooks

.git/hooks/pre-commit

git add -ugit commit -m "TEST checkstyle"

Starting audit...

/Users/user/[...]/com/atlassian/stash/web/projects/ProjectController.java:161:12: 'for' is not followed by whitespace.

Audit done.Commit aborted.

Branch from green builds

.git/hooks/post-checkout

$ git checkout mastermaster is lookin'good! c4f3b4b has 4 green builds. $ git checkout stable-2.3 DANGER! stable-2.3 is busted. e1324fa has 2 red builds.

Get it at: bitly.com/green-builds

What happens to CI with ?

4 What happens to CI with ?

What happens to CI with git?1


An explosion of branches2


An explosion of branches2

3 Performance degradation of build sys

Building everything is expensive1


Automatically build stable and master2


Automatically build stable and master2

3 Manually trigger feature branch builds

In Conclusion: the recipe

BranchingModel


Automation & CI setup

ConclusionsCollaboration

Model

BranchingModel



ConclusionsCollaboration

Model

Centralized

BranchingModel



Conclusions

Product workflow

CollaborationModel

Centralized

BranchingModel



Conclusions

Product workflow

Continuous delivery workflow

CollaborationModel

Centralized

BranchingModel



Conclusions

Product workflow


Embrace PR

CollaborationModel

Centralized

BranchingModel



Conclusions

Product workflow


Embrace PR

CollaborationModel

Centralized Merge vs Rebase

BranchingModel



Conclusions

Product workflow


Embrace PR

Single Repo or Forks

CollaborationModel

Centralized Merge vs Rebase

BranchingModel



Conclusions

Product workflow


Embrace PR

Single Repo or Forks

CollaborationModel

Centralized

Hooks, hooks everywhere

Merge vs Rebase

BranchingModel



Conclusions

Product workflow


Embrace PR

Build automatically,

but leave knobs!Single Repo

or Forks

CollaborationModel

Centralized

Hooks, hooks everywhere

Merge vs Rebase

Nicola PaolucciTHANK YOU FOR YOUR ATTENTION!

@durdndurdn.comShould I change the pic? ;-)

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real world git workflows - eclipsecon europe 2013

Technology

branch names

release branchrelease

feature3one branch

stable branchstable

git merge s

production staging

merge commit

git checkout stable