Working with Git

Working with Git
For the Android Developer
slideshare.net/thillerson
Tony Hillerson, AnDevCon Spring 2014

Presentation tackmobile.comPresentation tackmobile.com
About Me
• @thillerson, +thillerson
• Partner, Developer at Tack Mobile 
(tackmobile.com), @tackmobile
• Android, iOS, and Mobile Web
• Rails, Node, maybe Elixir (one day)

Presentation tackmobile.comPresentation tackmobile.com
What We’ll Cover Today
• The Git Database
• Conﬁguration
• Working with Multiple Repositories
• ssh, submodules, subtrees
• Advanced Querying
• Git Flow for Delivering Releases

Presentation tackmobile.com
The Git Database
Get Acquainted

.git
• Each git repository has a database in the .git
directory
• HEAD, FETCH_HEAD, ORIG_HEAD
• objects
• refs
• etc… hooks

Poking Around
• git show <commit>
• Shows blob contents, tree info, commit/ref
logs
• git ls-tree
• git rev-list

Conﬁguration
Get Comfortable

gitconfig locations
Global /etc/gitconfig
User ~/.gitconfig
Local Project 
(not shared)
.git/config
git-scm.com/book/en/Customizing-Git-Git-
Configuration

Conﬁgure Colors
• git conﬁg color.diff auto
• [color] 
diff = auto 
status = auto 
branch = auto 
ui = true

Conﬁgure Aliases
• git conﬁg alias.co checkout
• [alias] 
co = checkout 
cp = cherry-pick 
unstage = reset HEAD 
lop = log -p

Terse Log
• [alias] 
lol = log --pretty=format:'%Cred%h%Creset -
%C(yellow)%d%Creset %s %Cgreen(%cr)
%C(bold blue)<%an>%Creset' --abbrev-
commit --graph —decorate
• - Scott Chacon

You Have Questions
Get Answers

When Was The First Commit?
• Assuming “master” is the conventional
“master”:
• git log master --oneline | tail -n1

When Did This Branch Branch?
• git merge-base <branch> <parent>
• probably…
• git help merge-base

Do I Have The Latest Changes?
• git fetch - git must have the latest changes
locally to tell you
• git log develop..origin/develop
• If no commits - yes, you have the latest
• Tools like SourceTree will often do automatic
fetches

Do I Have Unpushed Changes?
• The opposite!
• git log origin/develop..develop

What’s Upstream?
• Upstream is the repository/branch from which
changes come
• ➜ git status
# On branch develop 
# Your branch is behind 'origin/develop' by 2
commits, and can be fast-forwarded. 
# (use "git pull" to update your local branch) 
# 
nothing to commit, working directory clean

Setting Upstream
• In .gitconﬁg: 
[branch] 
autosetupmerge = always
• git branch -u <remote> [branch]

Checking All Branches
• ➜ git branch -lvv
* develop 24c4398 [origin/develop: behind 2] 
warning ﬁxed. 
master 3cc12bb [origin/master: behind 3] 
Giving username an email keyboard for what seems to be the
common use case.
• Add -a to include remotes

Is This Branch Merged?
• Which branches contain a given commit?
• git branch --contains <branch/commit>
• ➜ git branch --contains develop
* develop
• ➜ git branch --contains master 
* develop 
master

Where Did This Bug Come From?
• git bisect!
• Known Good Commit <|> Latest Buggy Commit
• build and run
• mark a commit good or bad
• git walks forward or backward
• repeat

Where Did My Commit Go?
• Have you lost a commit you know you made?
• git reﬂog!

Working With
Multiple Repositories
Get Integrated

Local Repos
• git clone <path> <new path>
• git push origin <branch>
• git pull origin <branch>
WAT

ssh
• git clone ssh://user@host/path/.git
• Push to origin
• Pull from origin
• Use when just starting out a private project?

Multiple Remotes
• git remote add <path>
• git push otherremote branch
• git pull otherremote branch
• Why? other upstream repo, maybe a fork

Submodules
• A git repository tracked as part of the tree of
another repository
• Git (kind of) manages it
• cd in -> get another git repo
• Sort of a broken SVN external (the only thing I
like better about SVN than git)

Submodules: What are they good for?
• Dependencies
• That are under frequent development
• That are not distributed as a jar or through
maven

Submodules: Why do they suck?
• You have to be explicit about them; git won’t
manage them for you
• Devs on your team need to be educated
• Have to jump through hoops to connect the
repo back to its origin
• Hard to share local changes

Working with Submodules
• git submodule add <repo> <local name>
• .gitmodules
• Keeps submodule at a explicit commit
• ignore = dirty
• git submodule deinit, git rm

Submodules: Workﬂow
• If you need to move the submodule’s commit
• cd to submodule
• move to the new commit
• cd to parent
• git add and commit
• When you pull, add: 
git submodule update —install —recursive

Submodule Examples
• Utility Project

Submodule tips
• Avoid them.
• If you need to use them, make sure your team
understands them.

Subtrees
• Add repo contents directly to tree
• http://blogs.atlassian.com/2013/05/
alternatives-to-git-submodule-git-subtree/

Git Flow
Getting Apps Shipped

Git Flow
• Conventions to follow
• Tools to help you follow conventions
• http://nvie.com/posts/a-successful-git-
branching-model/

Git Flow Conventions: Master Branch
• The master branch is what is publicly available
now
• You don’t commit directly to master

Git Flow Conventions: Develop Branch
• A branch called “develop” is what will become
the next version
• Day to day work happens on develop
• “Integration branch”

Git Flow Conventions: Feature Branches
• Long running development go on feature
branches: “feature/foo”
• Long running: “more than one commit”
• Can be pushed to the server and shared
• Branch from develop

Git Flow Conventions: Hotfixes
• OMG Problems in Production, create a hotfix:
“hotfix/foo”
• Branch from master (not develop)

Git Flow Conventions: Releases
• When a release is almost ready on develop,
create a release branch: “release/2.0.4”
• Branch from develop
• Develop continues on for the next release
• Small changes to release go on release branch

Branch Lifecycle
• Features
• Start from develop
• Finished and merged to develop
• Releases
• Start from develop
• Finished and merged to master and develop

Git Flow in Action: Features
feature/somefeature
master
develop

Git Flow in Action: Releases
release/v1.0
master
develop

The Take Home
• You know your way around .git
• You can customize and conﬁgure git
• You understand submodules and where they
work (and don’t work)
• You know how git ﬂow can help when releasing
apps with a team

Thank you!
Working with Git for the Android Developer • Tony Hillerson
• Questions?
• We’re Hiring! careers@tackmobile.com
• Excellent Team
• Awesome Projects
• Great Ofﬁce

Working with Git

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