As your app code gets larger and more complex, it makes sense to break your project out into smaller reusable components. But what’s the best way to do this? How can you clearly version your internal libraries? What kind of setup and maintenance can you expect? How much could it slow down development time? In this talk we’ll dive into the various ways you can manage internal library dependencies. We’ll chat about the current state of Android dependency management, Gradle multi-project builds, Git submodules, and creating a private maven repository in Artifactory. The speaker will share real-world examples, and the pros and cons of each approach.

1. Internal Library
Dependency Management
@KellyShuster

2. @KellyShuster

3. @KellyShuster

7. dependency-sample dependency-sample-lib

9. Git Submodules
Google’s Repo Tool
Artifactory
Jitpack

10. Git Submodules

11. dependency-sample dependency-sample-lib
app mylibrary

14. 02-git-submodules

15. How do you set it up?

16. git submodule add <lib-repo>

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19. dependency-sample
|
+--.gitmodules
+--dependency-sample-library

20. [submodule "dependency-sample-library"]
path = dependency-sample-library
url = https://github.com/KioKrofovitch/dependency-sample-library.git
.gitmodules

21. Add Gradle References

22. settings.gradle
include ':app'
include ':dependency-sample-library:mylibrary'

23. build.gradle (app)
dependencies {
...
compile project(':dependency-sample-library:mylibrary')
}

24. Check Submodule Status

25. git submodule

29. How do you get code?

30. git clone <repo> --recursive

31. git clone <repo>
git submodule init
git submodule update

32. git checkout <branch>
git submodule init
git submodule update

33. git checkout <branch>

37. git submodule init

38. git submodule update

41. Upstream changes

42. git pull
git submodule update

43. Changing the library

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49. Committing on a Detached Head

51. How it happens

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58. 1bd7125
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59. How to recover

63. Removing Submodules

66. .gitmodules
.git/modules

67. Pros
Versioning brought to you by git

68. Pros
Versioning brought to you by git
Versioning is specific and repeatable

69. Pros
Versioning brought to you by git
Versioning is specific and repeatable
One Android Studio Project

70. Pros
Versioning brought to you by git
Versioning is specific and repeatable
One Android Studio Project
Code access

71. Cons
Magic is involved:

72. Cons
Magic is involved:
Working with a detached head

73. Cons
Magic is involved:
Working with a detached head
Pulling down latest submodule

74. Cons
Magic is involved:
Working with a detached head
Pulling down latest submodule
Adding & tracking submodule reference

75. Cons
Magic is involved:
Working with a detached head
Pulling down latest submodule
Adding & tracking submodule reference
Library versions are commit SHAs

76. Google’s Repo Tool

77. dependency-sample dependency-sample-lib
app mylibrary
dependency-parent
manifest

79. 04-repo-tool

80. How do you set it up?

81. dependency-parent
manifest

82. default.xml
<?xml version="1.0" encoding="UTF-8"?>
<manifest>
<remote ... />
<default ... />
<project ... />
</manifest>

83. default.xml
<?xml version="1.0" encoding="UTF-8"?>
<manifest>
<remote name="github"
fetch="https://github.com" />
<default ... />
<project ... />
<project ... />
</manifest>

84. default.xml
<?xml version="1.0" encoding="UTF-8"?>
<manifest>
<remote ... />
<default revision="master"
remote="github" />
<project ... />
</manifest>

85. default.xml
<?xml version="1.0" encoding="UTF-8"?>
<manifest>
<remote ... />
<default ... />
<project name="KioKrofovitch/dependency-sample"
</manifest>

86. default.xml
<?xml version="1.0" encoding="UTF-8"?>
<manifest>
<remote ... />
<default ... />
<project name="KioKrofovitch/dependency-sample"
remote="github"
</manifest>

87. default.xml
<?xml version="1.0" encoding="UTF-8"?>
<manifest>
<remote ... />
<default ... />
<project name="KioKrofovitch/dependency-sample"
remote="github"
revision="04-repo-tool"
</manifest>

88. default.xml
<?xml version="1.0" encoding="UTF-8"?>
<manifest>
<remote ... />
<default ... />
<project name="KioKrofovitch/dependency-sample"
remote="github"
revision="04-repo-tool"
path="dependency-sample"/>
</manifest>

89. default.xml
<?xml version="1.0" encoding="UTF-8"?>
<manifest>
<remote ... />
<default ... />
<project name="KioKrofovitch/dependency-sample"
remote="github"
revision="04-repo-tool"
path="dependency-sample"/>
<project name="KioKrofovitch/dependency-sample-library"
remote="github"
path="dependency-sample-library"/>
</manifest>

90. default.xml
<?xml version="1.0" encoding="UTF-8"?>
<manifest>
<remote ... />
<default ... />
<project name="KioKrofovitch/dependency-sample"
remote="github"
revision="04-repo-tool"
path="dependency-sample"/>
<project name="KioKrofovitch/dependency-sample-library"
remote="github"
path="dependency-sample-library"/>
</manifest>

91. repo init -u <parent-repo>

92. parent
|
+--.repo

93. repo sync

94. parent
|
+--.repo
+--dependency-sample
+--dependency-sample-library

95. Add Gradle References

96. settings.gradle
include ':app'
include ':mylibrary'

97. settings.gradle
include ':app'
include ':mylibrary'
project(':mylibrary').projectDir
= new File('../dependency-sample-library/mylibrary')

98. build.gradle
dependencies {
...
compile project(':mylibrary')
}

101. 78c7046
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102. Pros
Versioning is a “flexible” version of git

103. Pros
Versioning is a “flexible” version of git
Versions are clearly defined in one place

104. Pros
Versioning is a “flexible” version of git
Versions are clearly defined in one place
One Android Studio project

105. Pros
Versioning is a “flexible” version of git
Versions are clearly defined in one place
One Android Studio project
Code access

106. Pros
Versioning is a “flexible” version of git
Versions are clearly defined in one place
One Android Studio project
Code access
It’s cool because AOSP uses it

107. Cons
Overkill?

108. Cons
Overkill?
Repo + Git

109. Cons
Overkill?
Repo + Git
Detached head++

110. Cons
Overkill?
Repo + Git
Detached head++
Documentation / Community

111. Cons
Overkill?
Repo + Git
Detached head++
Documentation / Community
Less repeatable builds

112. Multiple Repositories,
Linked Using Maven

113. Artifactory

114. dependency-sample dependency-sample-lib
app
Artifactory
mylibrary

115. dependency-sample dependency-sample-lib
app mylibrary
Artifactory
Reference

116. dependency-sample dependency-sample-lib
app
Artifactory
Publish
mylibrary

117. 03-artifactory

119. Publishing

121. build.gradle (project level)
buildscript {
repositories {
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:1.3.0'
classpath "org.jfrog.buildinfo:build-info-extractor-gradle:3.1.1"
// NOTE: Do not place your application dependencies here; they
// belong in the individual module build.gradle files
}
}

122. build.gradle (project level)
buildscript {
repositories {
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:1.3.0'
classpath "org.jfrog.buildinfo:build-info-extractor-gradle:3.1.1"
// NOTE: Do not place your application dependencies here; they
// belong in the individual module build.gradle files
}
}

123. build.gradle (mylibrary)
apply plugin: 'com.android.library'
apply plugin: 'com.jfrog.artifactory'
apply plugin: 'maven-publish'
def packageName = 'com.kiodev.myArtLibrary'
def versionMajor = '1'
def versionMinor = '0'
def versionPatch = '0'
def libraryVersion = "${versionMajor}.${versionMinor}.${versionPatch}"
android { … }
dependencies { … }
publishing { … }
artifactory { … }

124. build.gradle (mylibrary)
apply plugin: 'com.android.library'
apply plugin: 'com.jfrog.artifactory'
apply plugin: 'maven-publish'
def packageName = 'com.kiodev.myArtLibrary'
def versionMajor = '1'
def versionMinor = '0'
def versionPatch = '0'
def libraryVersion = "${versionMajor}.${versionMinor}.${versionPatch}"
android { … }
dependencies { … }
publishing { … }
artifactory { … }

125. build.gradle (mylibrary)
apply plugin: 'com.android.library'
apply plugin: 'com.jfrog.artifactory'
apply plugin: 'maven-publish'
def packageName = 'com.kiodev.myArtLibrary'
def versionMajor = '1'
def versionMinor = '0'
def versionPatch = '0'
def libraryVersion = "${versionMajor}.${versionMinor}.${versionPatch}"
android { … }
dependencies { … }
publishing { … }
artifactory { … }

126. build.gradle (mylibrary)
apply plugin: 'com.android.library'
apply plugin: 'com.jfrog.artifactory'
apply plugin: 'maven-publish'
def packageName = 'com.kiodev.myArtLibrary'
def versionMajor = '1'
def versionMinor = '0'
def versionPatch = '0'
def libraryVersion = "${versionMajor}.${versionMinor}.${versionPatch}"
android { … }
dependencies { … }
publishing { … }
artifactory { … }

127. build.gradle (mylibrary)
publishing {
publications {
aar(MavenPublication) {
groupId packageName
version = libraryVersion
artifactId project.getName()
// Tell maven to prepare the generated "*.aar" file for publishing
artifact("$buildDir/outputs/aar/${project.getName()}-release.aar")
}
}
}

128. build.gradle (mylibrary)
artifactory {
contextUrl = 'http://localhost:8081/artifactory'
publish {
repository {
...
}
defaults {
...
}
}
}

129. build.gradle (mylibrary)
artifactory {
contextUrl = 'http://localhost:8081/artifactory'
publish {
repository {
// The Artifactory repository key to publish to
repoKey = 'libs-release-local'
// Defined in gradle.properties
username = artifactory_user
password = artifactory_password
}
defaults { … }
}
}

130. build.gradle (mylibrary)
artifactory {
contextUrl = 'http://localhost:8081/artifactory'
publish {
repository { ... }
defaults {
// Tell the Artifactory Plugin which artifacts to publish
publications('aar')
publishArtifacts = true
// Properties to be attached to the published artifacts.
properties = ['qa.level': 'basic', 'dev.team': 'core']
// Publish generated POM files to Artifactory (true by default)
publishPom = true
}
}
}

131. gradle assemble artifactoryPublish

133. Referencing

134. build.gradle (project level)
allprojects {
repositories {
jcenter()
maven {
url "http://localhost:8081/artifactory/libs-release-local"
// Defined in gradle.properties
credentials {
username = artifactory_user
password = artifactory_password
}
}
}
}

135. build.gradle (app)
android {
…
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
testCompile 'junit:junit:4.12'
compile 'com.android.support:appcompat-v7:23.0.1'
compile 'com.android.support:design:23.0.1'
compile(group: 'com.kiodev.myArtLibrary', name: 'mylibrary',
version: '1.0.0', ext: 'aar')
}

136. build.gradle (app)
android {
…
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
testCompile 'junit:junit:4.12'
compile 'com.android.support:appcompat-v7:23.0.1'
compile 'com.android.support:design:23.0.1'
compile(group: 'com.kiodev.myArtLibrary', name: 'mylibrary',
version: '1.0.0', ext: 'aar')
}

137. gradle build --refresh-dependencies

140. Github
Code changes
& commits

141. Github Github
Code changes
& commits
Pull request
& merge

142. Github Github Artifactory
Code changes
& commits
Pull request
& merge Publish

143. Github Artifactory
Code changes
Publish

144. Pros
Versioning is human readable / determined

145. Pros
Versioning is human readable / determined
Benefits of JAR / AAR

146. Pros
Versioning is human readable / determined
Benefits of JAR / AAR
Potential to be highly automated

147. Cons
Versioning has zero tie to git

148. Cons
Versioning has zero tie to git
Low security

149. Cons
Versioning has zero tie to git
Low security
2 Android Studio Projects

150. Cons
Versioning has zero tie to git
Low security
2 Android Studio Projects
Stepping through code is harder

151. Cons
Versioning has zero tie to git
Low security
2 Android Studio Projects
Stepping through code is harder
Extra step of publishing

152. Jitpack

153. dependency-sample dependency-sample-lib
app
Jitpack
mylibrary

155. 05-jitpack

156. build.gradle (project level)
allprojects {
repositories {
jcenter()
maven {
url "https://jitpack.io"
credentials { username authToken }
}
}
}

157. build.gradle (project level)
allprojects {
repositories {
jcenter()
maven {
url "https://jitpack.io"
credentials { username authToken }
}
}
}

158. build.gradle (app level)
dependencies {
...
compile 'com.github.User:repo:version'
}

159. build.gradle (app level)
dependencies {
compile
'com.github.KioKrofovitch:
dependency-sample-library:
02-git-submodules-SNAPSHOT'
}

160. <tag>
-SNAPSHOT
<branch>-SNAPSHOT
<short commit SHA>

161. gradle build --refresh-dependencies

162. Pros
Versioning:
Human readable AND managed by Git

163. Pros
Versioning:
Human readable AND managed by Git
Benefits of JAR / AAR

164. Pros
Versioning:
Human readable AND managed by Git
Benefits of JAR / AAR
No publishing stress

165. Cons
Waiting for publishing

166. Cons
Waiting for publishing
Potential for non-repeatable builds

167. Cons
Waiting for publishing
Potential for non-repeatable builds
2 Android Studio Projects

168. Cons
Waiting for publishing
Potential for non-repeatable builds
2 Android Studio Projects
Stepping through code is harder

169. Git Submodules
Google’s Repo Tool
Artifactory
Jitpack

170. @KellyShuster
https://github.com/KioKrofovitch/
dependency-sample
dependency-sample-library
dependency-parent

171. Resources
Git submodule
https://git-scm.com/docs/git-submodule
https://git-scm.com/book/en/v2/Git-Tools-Submodules
Repo Tool
http://www.instructables.com/id/Using-Googles-repo-command-in-your-own-projects/
Artifactory Open Source
https://www.jfrog.com/open-source/
Artifactory Professional
https://www.jfrog.com/artifactory/
Artifactory OS Tutorial
https://jeroenmols.github.io/blog/2015/08/06/artifactory/

172. Photo Credits
Android Robot
https://commons.wikimedia.org/wiki/File:Android_robot.svg
Trinity College Library
https://en.wikipedia.org/wiki/Trinity_College,_Dublin#/media/File:Long_Room_Interior,
_Trinity_College_Dublin,_Ireland_-_Diliff.jpg
Ruby
http://nicholasjohnson.com/ruby/
Clean Desk
http://www.levo.com/articles/career-advice/what-your-desk-says-about-you
Messy Desk
http://www.telegraph.co.uk/news/newstopics/howaboutthat/10225664/Having-a-messy-desk-makes-you-more-
creative.html
Headless Horseman Gif
https://www.lovethisgif.com/tag/headless+horseman
Ghost
http://38.media.tumblr.com/d30fe069cc48e11eeb31ae08293a159e/tumblr_nbtdxg9d6n1szf0nzo1_250.gif

173. Photo Credits
Neverending Story Book
http://www.dailyrecord.co.uk/entertainment/tv-radio/flashback-friday-neverending-story-proves-4948514
Unicorn w/ Rainbows
http://souloftruth.com/the-race-to-nowhere/
John Wayne
http://patch.com/california/sanclemente/best-ways-recycle-water-during-californias-dry-spell
Space Pic
http://wallpapershidef.com/outer-space-desktop-wallpaper.html
Computer
https://commons.wikimedia.org/wiki/File:Gnome-computer.svg
Crying Pikachu
http://gifrific.com/wp-content/uploads/2012/06/Picachu-crying-pokemon.gif
Branch
http://townhack.github.io/git-101/img/git-branch.png

174. Photo Credits
Maven Logo
https://commons.wikimedia.org/wiki/File:Maven_logo.svg