Rock The Gradle MobileEra

More often than none, an Android project's build.gradle files grow larger and more complex with time. This talk will look at the underappreciated buildSrc folder, which allows you to create plugins directly from your project, but also can help you make your build.gradle files cleaner and more readable.

Transcript

1. Xavier F. Gouchet, Senior Software Engineer @xgouchet Rock the Gradle, Rule the world
3. INTRODUCTION 0 A (brief) Gradle introduction
4. WHAT IS GRADLE ? General Purpose Language Agnostic Feature Agnostic Dependency Management System High performance Build Management Task Dependency Graph
5. THE GRADLE ALGORITHM INIT Launches the JVM Analyse the working directory Creates the Project object(s) Compiles the buildSrc module(s) CONFIG EXEC Executes all the build.gradle scripts Creates & configures tasks Resolve dependencies Execute the relevant tasks
6. BUILDSRC 1 “It’s a kind of Magic” — Queen
7. ┬ MyProject ├┬ app/ │├── src/ │└── build.gradle ├┬ buildSrc/ │├── src/ │├── build.gradle │└── settings.gradle ├─ build.gradle └─ settings.gradle Project Structure
8. ┬ MyProject ├┬ app/ │├── src/ │└── build.gradle ├┬ buildSrc/ │├── src/ │├── build.gradle │└── settings.gradle ├─ build.gradle └─ settings.gradle Project Structure
9. ┬ MyProject ├┬ app/ │├── src/ │└── build.gradle ├┬ buildSrc/ │├── src/ │├── build.gradle │└── settings.gradle ├─ build.gradle └─ settings.gradle Project Structure
10. ┬ MyProject ├┬ app/ │├── src/ │└── build.gradle ├┬ buildSrc/ │├── src/ │├── build.gradle │└── settings.gradle ├─ build.gradle └─ settings.gradle Project Structure
11. Works like any module in your project Compiled and tested before any gradle task Groovy, Java, Kotlin, … Any public class / method becomes available in gradle scripts How does it work?
12. Better dependency management Helper classes / methods Plugin configuration Custom plugin (Locally versioned with the project) What can we use it for?
13. ⚠ “A single change in buildSrc causes the whole project to become out-of-date.”
14. SCRIPTS 2 “Don’t repeat yourself” — Uncle Bob Martin
15. DEPENDENCIES Write Once Use Everywhere https://unsplash.com/@eliabevces
16. dependencies { implementation "org.jetbrains.kotlin:kotlin-stdlib:…" implementation "androidx.appcompat:appcompat:…" implementation "androidx.core:core-ktx:…" implementation "androidx.annotation:annotation:…" } Dependencies app/build.gradle
17. object Dependencies { object Versions { const val Kotlin = "1.3.50" const val AndroidX = "1.0.0" } // … } Dependencies buildSrc/src/main/kotlin/Dependencies.kt
18. object Dependencies { // … object Libraries { const val Kotlin = "org.jetbrains.kotlin:kotlin-stdlib:${Versions.Kotlin}" @JvmField val AndroidX = arrayOf( "androidx.appcompat:appcompat:${Versions.AndroidX}", "androidx.core:core-ktx:${Versions.AndroidX}", "androidx.annotation:annotation:${Versions.AndroidX}" ) } } Dependencies buildSrc/src/main/kotlin/Dependencies.kt
19. object Dependencies { // … object Libraries { const val Kotlin = "org.jetbrains.kotlin:kotlin-stdlib:${Versions.Kotlin}" @JvmField val AndroidX = arrayOf( "androidx.appcompat:appcompat:${Versions.AndroidX}", "androidx.core:core-ktx:${Versions.AndroidX}", "androidx.annotation:annotation:${Versions.AndroidX}" ) } } Dependencies buildSrc/src/main/kotlin/Dependencies.kt
20. object Dependencies { // … object Libraries { const val Kotlin = "org.jetbrains.kotlin:kotlin-stdlib:${Versions.Kotlin}" @JvmField val AndroidX = arrayOf( "androidx.appcompat:appcompat:${Versions.AndroidX}", "androidx.core:core-ktx:${Versions.AndroidX}", "androidx.annotation:annotation:${Versions.AndroidX}" ) } } Dependencies buildSrc/src/main/kotlin/Dependencies.kt
21. import Dependencies dependencies { implementation Dependencies.Libraries.Kotlin implementation Dependencies.Libraries.AndroidX } Dependencies app/build.gradle
22. CONFIGURATIONS Hide the bulk https://unsplash.com/@adigold1
23. detekt { toolVersion = "1.0.1" input = files("$projectDir/src/main/java") config = files("$project.rootDir/config/detekt.yml") reports.xml { enabled = true destination = file("build/reports/detekt.xml") } } check.dependsOn("detekt") Plugin Configuration app/build.gradle
24. fun Project.detektConfig() { val ext = extensions.findByType(DetektExtension::class) ext.version = "1.0.1" ext.input = files("$projectDir/src/main/kotlin") // … tasks.named("check") { dependsOn("detekt") } } Plugin Configuration buildSrc/src/main/kotlin/DetektConfig.kt
25. fun Project.detektConfig() { val ext = extensions.findByType(DetektExtension::class) ext.version = "1.0.1" ext.input = files("$projectDir/src/main/kotlin") // … tasks.named("check") { dependsOn("detekt") } } Plugin Configuration buildSrc/src/main/kotlin/DetektConfig.kt
26. fun Project.detektConfig() { val ext = extensions.findByType(DetektExtension::class) ext.version = "1.0.1" ext.input = files("$projectDir/src/main/kotlin") // … tasks.named("check") { dependsOn("detekt") } } Plugin Configuration buildSrc/src/main/kotlin/DetektConfig.kt
27. fun Project.detektConfig() { val ext = extensions.findByType(DetektExtension::class) ext.version = "1.0.1" ext.input = files("$projectDir/src/main/kotlin") // … tasks.named("check") { dependsOn("detekt") } } Plugin Configuration buildSrc/src/main/kotlin/DetektConfig.kt
28. fun Project.detektConfig() { val ext = extensions.findByType(DetektExtension::class) ext.version = "1.0.1" ext.input = files("$projectDir/src/main/kotlin") // … tasks.named("check") { dependsOn("detekt") } } Plugin Configuration buildSrc/src/main/kotlin/DetektConfig.kt
29. import detektConfig detektConfig() Plugin Configuration app/build.gradle
30. UTILITIES Expand your toolbox https://unsplash.com/@toddquackenbush
31. android { defaultConfig { versionCode 31401 versionName "3.14.1" } } Version Code & Version Name app/build.gradle
32. data class Version( val major: Int, val minor: Int, val hotfix: Int ) { val name = "$major.$minor.$hotfix" val code = (major × 10000) + (minor × 100) + hotfix } Version Code & Version Name buildSrc/src/main/kotlin/Version.kt
33. data class Version( val major: Int, val minor: Int, val hotfix: Int ) { val name = "$major.$minor.$hotfix" val code = (major × 10000) + (minor × 100) + hotfix } Version Code & Version Name buildSrc/src/main/kotlin/Version.kt
34. data class Version( val major: Int, val minor: Int, val hotfix: Int ) { val name = "$major.$minor.$hotfix" val code = (major × 10000) + (minor × 100) + hotfix } Version Code & Version Name buildSrc/src/main/kotlin/Version.kt
35. object App { val Version = Version(3, 14, 1) } Version Code & Version Name buildSrc/src/main/kotlin/App.kt
36. import App android { defaultConfig { versionCode App.Version.code versionName App.Version.name } } Version Code & Version Name app/build.gradle
37. PLUGINS 3 Now you’re thinking with Plugins
38. Variants Graph What a Plugin can do… Tasks Extensions Per-module configurations Configuration Project Task Dependencies
39. A concrete example Sharing localisation strings between platforms
40. TASK The Core Feature https://unsplash.com/@wanxi
41. A Custom Task open class GetStringsTask : DefaultTask() { var languages : Array<String> = arrayOf() var root = "" var baseUrl = "http://127.0.0.1" @TaskAction fun performTask() { for (l in languages) { Downloader.download("$baseUrl/$l/strings.xml", "$root/res/values-$l/strings.xml") } } } buildSrc/src/main/kotlin/GetStringsTask.kt
42. A Custom Task open class GetStringsTask : DefaultTask() { var languages : Array<String> = arrayOf() var root = "" var baseUrl = "http://127.0.0.1" @TaskAction fun performTask() { for (l in languages) { Downloader.download("$baseUrl/$l/strings.xml", "$root/res/values-$l/strings.xml") } } } buildSrc/src/main/kotlin/GetStringsTask.kt
43. A Custom Task open class GetStringsTask : DefaultTask() { var languages : Array<String> = arrayOf() var root = "" var baseUrl = "http://127.0.0.1" @TaskAction fun performTask() { for (l in languages) { Downloader.download("$baseUrl/$l/strings.xml", "$root/res/values-$l/strings.xml") } } } buildSrc/src/main/kotlin/GetStringsTask.kt
44. A Custom Task open class GetStringsTask : DefaultTask() { var languages : Array<String> = arrayOf() var root = "" var baseUrl = "http://127.0.0.1" @TaskAction fun performTask() { for (l in languages) { Downloader.download("$baseUrl/$l/strings.xml", "$root/res/values-$l/strings.xml") } } } buildSrc/src/main/kotlin/GetStringsTask.kt
45. A Custom Task open class GetStringsTask : DefaultTask() { var languages : Array<String> = arrayOf() var root = "" var baseUrl = "http://127.0.0.1" @TaskAction fun performTask() { for (l in languages) { Downloader.download("$baseUrl/$l/strings.xml", "$root/res/values-$l/strings.xml") } } } buildSrc/src/main/kotlin/GetStringsTask.kt
46. A Custom Task import GetStringsTask task downloadStrings(type: GetStringsTask) { languages = ["en", "fr"] root = "$projectDir/src/main" baseUrl = "https://example.org/locales" } app/build.gradle
47. EXTENSION Adding some flexibility https://unsplash.com/@glenncarstenspeters
48. A Custom Extension open class GetStringsExt( var languages: Array<String> = arrayOf(), var baseUrl: String = "http://127.0.0.1" ) buildSrc/src/main/kotlin/GetStringsExt.kt
49. A Custom Extension open class GetStringsTask : DefaultTask() { var root = "" var extension = GetStringsExt() @TaskAction fun performTask() { for (l in extension.languages) { val url = "${extension.baseUrl}/$l/strings.xml" val path = "$root/res/values-$l/strings.xml" Downloader.download(url, path) } } } buildSrc/src/main/kotlin/GetStringsTask.kt
50. A Custom Extension open class GetStringsTask : DefaultTask() { var root = "" var extension = GetStringsExt() @TaskAction fun performTask() { for (l in extension.languages) { val url = "${extension.baseUrl}/$l/strings.xml" val path = "$root/res/values-$l/strings.xml" Downloader.download(url, path) } } } buildSrc/src/main/kotlin/GetStringsTask.kt
51. A Custom Extension open class GetStringsTask : DefaultTask() { var root = "" var extension = GetStringsExt() @TaskAction fun performTask() { for (l in extension.languages) { val url = "${extension.baseUrl}/$l/strings.xml" val path = "$root/res/values-$l/strings.xml" Downloader.download(url, path) } } } buildSrc/src/main/kotlin/GetStringsTask.kt
52. A Custom Extension open class GetStringsTask : DefaultTask() { var root = "" var extension = GetStringsExt() @TaskAction fun performTask() { for (l in extension.languages) { val url = "${extension.baseUrl}/$l/strings.xml" val path = "$root/res/values-$l/strings.xml" Downloader.download(url, path) } } } buildSrc/src/main/kotlin/GetStringsTask.kt
53. A Custom Extension… and a Plugin class GetStringsPlugin : Plugin<Project> { override fun apply(project: Project) { val ext = project.extensions .create("getStrings", GetStringsExt::class.java) val task = project.tasks .create("getStrings", GetStringsTask::class.java) task.apply { root = "${project.projectDir.path}/src/main" extension = ext } } } buildSrc/src/main/kotlin/GetStringsPlugin.kt
54. A Custom Extension… and a Plugin class GetStringsPlugin : Plugin<Project> { override fun apply(project: Project) { val ext = project.extensions .create("getStrings", GetStringsExt::class.java) val task = project.tasks .create("getStrings", GetStringsTask::class.java) task.apply { root = "${project.projectDir.path}/src/main" extension = ext } } } buildSrc/src/main/kotlin/GetStringsPlugin.kt
55. A Custom Extension… and a Plugin class GetStringsPlugin : Plugin<Project> { override fun apply(project: Project) { val ext = project.extensions .create("getStrings", GetStringsExt::class.java) val task = project.tasks .create("getStrings", GetStringsTask::class.java) task.apply { root = "${project.projectDir.path}/src/main" extension = ext } } } buildSrc/src/main/kotlin/GetStringsPlugin.kt
56. A Custom Extension… and a Plugin class GetStringsPlugin : Plugin<Project> { override fun apply(project: Project) { val ext = project.extensions .create("getStrings", GetStringsExt::class.java) val task = project.tasks .create("getStrings", GetStringsTask::class.java) task.apply { root = "${project.projectDir.path}/src/main" extension = ext } } } buildSrc/src/main/kotlin/GetStringsPlugin.kt
57. A Custom Extension… and a Plugin class GetStringsPlugin : Plugin<Project> { override fun apply(project: Project) { val ext = project.extensions .create("getStrings", GetStringsExt::class.java) val task = project.tasks .create("getStrings", GetStringsTask::class.java) task.apply { root = "${project.projectDir.path}/src/main" extension = ext } } } buildSrc/src/main/kotlin/GetStringsPlugin.kt
58. A Custom Extension… and a Plugin class GetStringsPlugin : Plugin<Project> { override fun apply(project: Project) { val ext = project.extensions .create("getStrings", GetStringsExt::class.java) val task = project.tasks .create("getStrings", GetStringsTask::class.java) task.apply { root = "${project.projectDir.path}/src/main" extension = ext } } } buildSrc/src/main/kotlin/GetStringsPlugin.kt
59. A Custom Extension… and a Plugin import GetStringsPlugin apply plugin: GetStringsPlugin getStrings { languages = ["en", "fr"] baseUrl = "https://example.org/locales" // no need to specify the root path anymore } app/build.gradle
60. The extension makes it easy to configure The plugin can fill in properties automatically The plugin can generate tasks per variant The plugin can manipulate the graph Why use a Plugin+Extension
61. GOING FURTHER 4 “Don't stop me now (cause I’m having a good time!)” — Queen
62. TASK GRAPH Where the Magic happen https://unsplash.com/@bill_oxford
63. Ordering Tasks class GetStringsPlugin : Plugin<Project> { override fun apply(project: Project) { // … project.afterEvaluate { p -> p.tasks .withType(GenerateResValues::class.java) { it.dependsOn(task) } } } } buildSrc/src/main/kotlin/GetStringsPlugin.kt
64. Ordering Tasks class GetStringsPlugin : Plugin<Project> { override fun apply(project: Project) { // … project.afterEvaluate { p -> p.tasks .withType(GenerateResValues::class.java) { it.dependsOn(task) } } } } buildSrc/src/main/kotlin/GetStringsPlugin.kt
65. Ordering Tasks class GetStringsPlugin : Plugin<Project> { override fun apply(project: Project) { // … project.afterEvaluate { p -> p.tasks .withType(GenerateResValues::class.java) { it.dependsOn(task) } } } } buildSrc/src/main/kotlin/GetStringsPlugin.kt
66. SIDENOTE ON TASK ORDER STRICT A.dependsOn(B) C.finalizedBy(B) LOOSE D.mustRunAfter(B) E.shouldRunAfter(B)
67. SIDENOTE ON TASK ORDER LOOSE D.mustRunAfter(B) E.shouldRunAfter(B) $ gradle D > Task :app:D BUILD SUCCESSFUL in 4s 1 task executed
68. SIDENOTE ON TASK ORDER LOOSE D.mustRunAfter(B) E.shouldRunAfter(B) $ gradle D B > Task :app:B > Task :app:D BUILD SUCCESSFUL in 8s 2 tasks executed
69. SIDENOTE ON TASK ORDER LOOSE D.mustRunAfter(B) E.shouldRunAfter(B) $ gradle E > Task :app:E BUILD SUCCESSFUL in 15s 1 task executed
70. SIDENOTE ON TASK ORDER LOOSE D.mustRunAfter(B) E.shouldRunAfter(B) $ gradle E B > Task :app:B > Task :app:E BUILD SUCCESSFUL in 16s 2 tasks executed
71. SIDENOTE ON TASK ORDER LOOSE D.mustRunAfter(B) E.shouldRunAfter(B) B.dependsOn(A) A.dependsOn(E) $ gradle E B > Task :app:E > Task :app:A > Task :app:B BUILD SUCCESSFUL in 23s 3 tasks executed
72. PLUGIN INTEGRATION Help the developer use your Plugin https://unsplash.com/@momentsbygabriel
73. Aliasing the Plugin apply plugin: "java-gradle-plugin" gradlePlugin { plugins { getStrings { id = "getStrings" // the alias implementationClass = "GetStringsPlugin" } } } buildSrc/build.gradle
74. Aliasing the Plugin import GetStringsPlugin apply plugin: GetStringsPlugin app/build.gradle
75. Aliasing the Plugin apply plugin: "getStrings" app/build.gradle
76. Task’s group & description class GetStringsPlugin : Plugin<Project> { init { group = "mobileEra" description = "Downloads strings.xml from server." } // … } buildSrc/src/main/kotlin/GetStringsPlugin.kt
77. Android tasks ------------- androidDependencies - Displays the Android dependencies. sourceSets - Prints out all the source sets in the project. MobileEra tasks --------------- getStrings - Downloads strings.xml from a server. Verification tasks ------------------ lint - Runs lint on all variants. Task’s group & description $ gradlew :app:tasks
78. Android tasks ------------- androidDependencies - Displays the Android dependencies. sourceSets - Prints out all the source sets in the project. MobileEra tasks --------------- getStrings - Downloads strings.xml from a server. Verification tasks ------------------ lint - Runs lint on all variants. Task’s group & description $ gradlew :app:tasks
79. GRADLE CACHE Avoid unnecessary work https://unsplash.com/@jasonrobertsphotography
80. buildSrc/src/main/kotlin/GetStringsTask.kt Defining Inputs & Outputs open class GetStringsTask : DefaultTask() { @Input fun getLanguagesInputs(): List<String> { return extension.languages.toList() } @Input fun getBaseUrlInput(): String { return extension.baseUrl } }
81. buildSrc/src/main/kotlin/GetStringsTask.kt Defining Inputs & Outputs open class GetStringsTask : DefaultTask() { @OutputFiles fun getTaskOutputs(): List<File> { return extension.languages.map { l -> File("$root/res/values-$l/strings.xml") } } }
82. It will never update until we change the config ?
83. buildSrc/src/main/kotlin/GetStringsTask.kt Defining Inputs & Outputs open class GetStringsTask : DefaultTask() { @Input fun getDateInput() : String { val formatter = DateTimeFormatter.ISO_DATE return LocalDateTime.now().format(formatter) } }
84. INCREMENTAL TASKS Avoid unnecessary work https://unsplash.com/@pluyar
85. buildSrc/src/main/kotlin/GetStringsTask.kt Incremental Task open class GetStringsTask : DefaultTask() { @TaskAction fun incrementAction(inputs: IncrementalTaskInputs) { if (inputs.isIncremental) { inputs.outOfDate { println("Out of date: $it") } inputs.removed { println("Removed: $it") } } else { // … } } }
86. buildSrc/src/main/kotlin/GetStringsTask.kt Incremental Task open class GetStringsTask : DefaultTask() { @TaskAction fun incrementAction(inputs: IncrementalTaskInputs) { if (inputs.isIncremental) { inputs.outOfDate { println("Out of date: $it") } inputs.removed { println("Removed: $it") } } else { // … } } }
87. buildSrc/src/main/kotlin/GetStringsTask.kt Incremental Task open class GetStringsTask : DefaultTask() { @TaskAction fun incrementAction(inputs: IncrementalTaskInputs) { if (inputs.isIncremental) { inputs.outOfDate { println("Out of date: $it") } inputs.removed { println("Removed: $it") } } else { // … } } }
88. buildSrc/src/main/kotlin/GetStringsTask.kt Incremental Task open class GetStringsTask : DefaultTask() { @TaskAction fun incrementAction(inputs: IncrementalTaskInputs) { if (inputs.isIncremental) { inputs.outOfDate { println("Out of date: $it") } inputs.removed { println("Removed: $it") } } else { // … } } }
89. buildSrc/src/main/kotlin/GetStringsTask.kt Incremental Task open class GetStringsTask : DefaultTask() { @TaskAction fun incrementAction(inputs: IncrementalTaskInputs) { if (inputs.isIncremental) { inputs.outOfDate { println("Out of date: $it") } inputs.removed { println("Removed: $it") } } else { // … } } }
90. buildSrc/src/main/kotlin/GetStringsTask.kt Incremental Task open class GetStringsTask : DefaultTask() { @TaskAction fun incrementAction(inputs: IncrementalTaskInputs) { if (inputs.isIncremental) { inputs.outOfDate { println("Out of date: $it") } inputs.removed { println("Removed: $it") } } else { // … } } }
91. TESTING YOUR PLUGIN #TestMatters Caspar Benson / Getty Images
92. PLUGIN Only test the action of the Plugin itself INTEGRATION Dummy project to test real life scenarios Testing a Gradle Plugin buildSrc is tested on each build! TASK Delegate to other classes as much as possible
93. CREATING A DSL Simplify the configuration https://unsplash.com/@ratushny
94. app/build.gradle Creating a DSL getStrings { baseUrl = "https://example.org/locales" variants { debug { languages = ["en"] } free { languages = ["en", "fr"] } fullRelease { languages = ["en", "fr", "es"] } } }
95. DSL can go as deep as you need
96. GENERATING STUFF Delegate the tedious tasks https://unsplash.com/@lennykuhne
97. Generating Files Android Manifest Source code (JavaPoet / KotlinPoet) Resources (Strings, Drawables, Layouts, NavGraph, …) Assets…
98. ⚠ “Make sure your generator task is executed at the right moment.”
99. WRAPPING UP 5 You can enter here the subtitle if you need it
100. buildSrc is always built and tested Take away A single change in buildSrc invalidates all tasks Publish your plugins
101. Your build scripts are still code. Keep them as clean, maintainable and understandable as your production code.
102. Get the slides at https://speakerdeck.com/xgouchet/rock-the-gradle-mobileera Check sample project at https://github.com/xgouchet/RockTheGradle/
103. CREDITS: This presentation template was created by Slidesgo, including icons by Flaticon, and infographics & images by Freepik. Do you have any questions? @xgouchet @datadoghq THANK YOU!