Exploring Dynamic Feature Modules

Dynamic Feature Modules were announced in 2018 as a new way to modularize and deliver Android apps. It presents a way to decouple features entirely from one another, and avoid a "monoapp" which depends on all code in one place. It has benefits to compile times, app installation size, and enables instant apps - but the feature has had little buzz since then, unknown adoption, and seemingly goes unmaintained now.

Let's change that!

In this talk we'll spend a bit of time reintroducing the dynamic feature Gradle plugin and explain what it's used for, showcase how to extend an existing monoapp with dynamic features, start a new app from scratch and include your existing monoapp as a feature, and uncover all of the gotchas and oddities while doing it.

Transcript

1. Exploring Dynamic Features Alec Strong
2. Agenda • Getting Started • Cash App Modularization • Starting fresh with dynamic feature modules • Implementation and gotchas
3. Patchwork Plaid A modularization story github.com/AlecStrong/boxapp
7. app feature application library dynamic feature api Implements
8. app feature application library dynamic feature api Implements
9. feature plugins { alias(libs.plugins.android.dynamic.feature) alias(libs.plugins.kotlin.android) } android { namespace "app.cash.boxapp.smallboxfeature" } dependencies { implementation projects.app }
10. feature <manifest xmlns:android="http://schemas.android.com/apk/res/android" xmlns:dist="http://schemas.android.com/apk/distribution"> <dist:module dist:instant="false" dist:title="@string/smallboxfeature_title"> <dist:delivery> <dist:install-time /> </dist:delivery> <dist:fusing dist:include="true" /> </dist:module> </manifest>
11. app feature
12. app plugins { alias(libs.plugins.android.application) alias(libs.plugins.kotlin.android) } android { namespace "app.cash.boxapp" dynamicFeatures = [":bigboxfeature", ":smallboxfeature"] }
13. app feature application library dynamic feature api Implements
14. app feature application library dynamic feature api Implements
15. When to use them
16. Huge install size
17. Regionalization
18. Huge team
20. application library dynamic feature api Implements Date App Size # Commits Release 2016-02-28 11.42 MB 5771 2.10.0 app
21. app application library dynamic feature api Implements Date App Size # Commits Release 2016-06-15 9.77 MB 6638 2.11.0 keypad
22. application library dynamic feature api Implements Date App Size # Commits Release 2016-09-13 10.45 MB 7520 2.13.2 app app app keypad wire
23. application library dynamic feature api Implements Date App Size # Commits Release 2016-12-19 11.88 MB 8460 2.14.0 app keypad wire protos
24. application library dynamic feature api Implements Date App Size # Commits Release 2017-04-26 13.42 MB 9604 2.15.0 app keypad keypad protos db api address- typeahead scannerview scannerview- sample preferences signature scrubbing
25. application library dynamic feature api Implements Date App Size # Commits Release 2017-04-26 13.42 MB 9604 2.15.1 app protos db api ui-utility sample app
26. application library dynamic feature api Implements Date App Size # Commits Release 2017-08-14 14.94 MB 10585 2.18.1 app protos db api ui-utility sample app backend- utility backend util-hell presenters
27. application library dynamic feature api Implements Date App Size # Commits Release 2017-08-14 14.94 MB 10585 2.18.1 40 modules!
28. application library dynamic feature api Implements Date App Size # Commits Release 2019-01-18 26.65 MB 16588 2.43.0 app ui-utility sample app backend-utility util-hell protos db api backend presenters viewmodels protos db api backend presenters viewmodels
29. application library dynamic feature api Implements Date App Size # Commits Release 2019-01-18 26.65 MB 16588 2.43.0 app protos db api ui-utility sample app backend-utility backend util-hell presenters viewmodels Investing protos db api backend presenters viewmodels
30. application library dynamic feature api Implements Date App Size # Commits Release 2019-01-18 26.65 MB 16588 2.43.0 ui-utility sample app backend-utility util-hell presenters viewmodels Investing protos db api backend presenters viewmodels app backend protos db api
31. Scheduled Payments proto db api backen presenter application library dynamic feature api Implements Date App Size # Commits Release 2019-03-08 25.28 MB 17102 2.46.0 db api ui-utility sample app backend-utility util-hell presenters viewmodels backend:impl protos app backend:api Investing protos db api backend presenters viewmodels
32. application library dynamic feature api Implements Date App Size # Commits Release 2019-03-27 25.28 MB 17105 2.46.1 db api ui-utility sample app backend-utility util-hell presenters viewmodels backend:impl protos app backend:api Investing proto db api backen presenter Scheduled Payments proto db api backen presenter common-hell
33. application library dynamic feature api Implements Date App Size # Commits Release 2019-03-27 25.28 MB 17105 2.46.1 80 modules!
34. application library dynamic feature api Implements Date App Size # Commits Release 2019-07-25 26.34 MB 19733 2.55.0 db api ui-utility sample app backend-utility util-hell presenters viewmodels backend:impl protos app backend:api Investing proto db api backen presenter Scheduled Payments proto db api backen presenter common-hell Boost proto db api backen presenter Card Drawer proto db api backen presenter
35. application library dynamic feature api Implements Date App Size # Commits Release 2019-09-26 27.03 MB 21478 2.59.0 db api ui-utility sample app backend-utility util-hell presenters viewmodels backend:impl protos app backend:api Investing proto db api backen presenter Scheduled Payments proto db api backen presenter common-hell Boost proto db api backen presenter Card Drawer proto db api backen presenter Lending proto db api backen presenter Support proto db api backen presenter qr-codes proto db api backen presenter Google pay proto db api backen presenter
36. application library dynamic feature api Implements Date App Size # Commits Release 2019-10-17 27.01 MB 22025 3.0.1 db api ui-utility sample app backend-utility util-hell presenters viewmodels backend:impl app backend:api Investing proto db api backen presenter Scheduled Payments proto db api backen presenter common-hell Boost proto db api backen presenter Card Drawer proto db api backen presenter Lending proto db api backen presenter Support proto db api backen presenter qr-codes proto db api backen presenter Google pay proto db api backen presenter protos
37. application library dynamic feature api Implements Date App Size # Commits Release 2020-01-08 37.25 MB 24223 3.5.1 db api ui-utility sample app backend-utility util-hell presenters viewmodels backend:impl app backend:api Investing proto db api backen presenter Scheduled Payments proto db api backen presenter common-hell Boost proto db api backen presenter Card Drawer proto db api backen presenter Lending proto db api backen presenter Support proto db api backen presenter qr-codes proto db api backen presenter Google pay proto db api backen presenter protos recurring proto db api backen presenter liveness-check proto db api backen presenter
38. application library dynamic feature api Implements Date App Size # Commits Release 2020-03-15 41.60 MB 26076 3.10.0 db api ui-utility sample app backend-utility util-hell presenters viewmodels backend:impl app backend:api Investing proto db api backen presenter Scheduled Payments proto db api backen presenter common-hell Boost proto db api backen presenter Card Drawer proto db api backen presenter Lending proto db api backen presenter Support proto db api backen presenter qr-codes proto db api backen presenter Google pay proto db api backen presenter protos recurring proto db api backen presenter liveness-check proto db api backen presenter app-messages proto db api backen presenter bitcoin proto db api backen presenter
39. application library dynamic feature api Implements Date App Size # Commits Release 2020-03-15 41.60 MB 26076 3.10.0 200 modules!
40. application library dynamic feature api Implements Date App Size # Commits Release 2022-08-19 81.43 MB 55805 3.72.0 db api ui-utility sample app backend- utility util-hell presenters viewmodel backend:imp app backend:api Investin proto db api backe presente Scheduled proto db api backe presente common-hell Boost proto db api backe presente Card Drawer proto db api backe presente Lending proto db api backe presente Support proto db api backe presente qr- proto db api backe presente Google pay proto db api backe presente protos recurring proto db api backe presente liveness-check proto db api backe presente app-messages proto db api backe presente bitcoin proto db api backe presente
41. application library dynamic feature api Implements Date App Size # Commits Release 2022-08-19 81.43 MB 55805 3.72.0 800 modules!
42. application library dynamic feature api Implements Date App Size # Commits Release 2022-08-19 81.43 MB 55805 3.72.0
43. application library dynamic feature api Implements Date App Size # Commits Release 2022-08-19 81.43 MB 55805 3.72.0
44. application library dynamic feature api Implements Date App Size # Commits Release 2022-08-19 81.43 MB 55805 3.72.0 db api ui-utility sample app backend- utility util-hell presenters viewmodel backend:imp app backend:api Investin proto db api backe presente Scheduled proto db api backe presente common-hell Boost proto db api backe presente Card Drawer proto db api backe presente Lending proto db api backe presente Support proto db api backe presente qr- proto db api backe presente Google pay proto db api backe presente protos recurring proto db api backe presente liveness-check proto db api backe presente app-messages proto db api backe presente bitcoin proto db api backe presente
46. So what’s the problem?
47. application library dynamic feature api Implements app db api ui-utility sample app backend- utility util-hell presenters viewmodel backend:imp backend:api Investin proto db api backe presente Scheduled proto db api backe presente common-hell Boost proto db api backe presente Card Drawer proto db api backe presente Lending proto db api backe presente Support proto db api backe presente qr- proto db api backe presente Google pay proto db api backe presente protos recurring proto db api backe presente liveness-check proto db api backe presente app-messages proto db api backe presente bitcoin proto db api backe presente
48. application library dynamic feature api Implements app Card feature1 feature2 Inv Schedul Boost Le Su qr- Google recurrin liveness- app- bitcoin
49. application library dynamic feature api Implements app Card Drawer proto db api backe presente Inv Schedul Boost Le Su qr- Google recurrin liveness- app- bitcoin feature1 feature2
50. application library dynamic feature api Implements app Inv Schedul Boost Le Su qr- Google recurrin liveness- app- bitcoin
51. application library dynamic feature api Implements app Inv Schedul Boost Le Su qr- Google recurrin liveness- app- bitcoin app2
52. Too good to be true
53. Gotcha 1 Diamond Dependencies
54. > Task :boxapp:checkInternalDebugLibraries FAILED FAILURE: Build failed with an exception. * What went wrong: Execution failed for task ‘:boxapp:checkInternalDebugLibraries'. > [:app, :app] all package the same library [androidx.lifecycle:lifecycle-service].
55. tasks.withType(com.android.build.gradle.internal.tasks.CheckMultiApkLibrariesTask) .configureEach { enabled = false } app2 !
56. Gotcha 2 Manifest Merging
57. Installation did not succeed. The application could not be installed: INSTALL_PARSE_FAILED_MANIFEST_MALFORMED List of apks: [0] '/Users/astrong/Development/Android/cash-android/cash-os/build/intermediates/apk/internal/debug/cash-os-internal debug.apk' [1] '/Users/astrong/Development/Android/cash-android/app/build/intermediates/apk/internal/debug/app-internal-debug. [2] '/Users/astrong/Development/Android/cash-android/bigboxfeature/build/intermediates/apk/debug/bigboxfeature-deb [3] '/Users/astrong/Development/Android/cash-android/bigboxfeature/api/build/intermediates/apk/debug/api-debug.apk [4] '/Users/astrong/Development/Android/cash-android/smallboxfeature/build/intermediates/apk/debug/smallboxfeature debug.apk' Installation failed due to: 'Failed to commit install session 1726590139 with command package install-commit 1726590139. E INSTALL_PARSE_FAILED_MANIFEST_MALFORMED: Failed parse during installPackageLI: /data/app/vmdl1726590139.tmp/base Binary XML file line #163): <meta-data> requires an android:value or android:resource attribute' Retry Failed to launch an application on all devices
58. Gotcha 2.1 Running from the IDE
59. > Task :cash-os:installInternalDebug Generating APKs for device 'Pixel_4a_API_32(AVD) - 12' for :cash-os:internalDebug The APKs have been extracted in the directory: /var/folders/9g/ 4r7qgd5s1096hyk8r_nzsw940000gn/T/apkSelect1137704977225312066 Installing APKs 'base-xxhdpi.apk, base-master.apk, base-en.apk, base-arm64_v8a.apk' on 'Pixel_4a_API_32(AVD) - 12' for :cash-os:internalDebug [SplitApkInstallerBase]: Failed to commit install session 1207711244 with command cmd package install-commit 1207711244. Error: INSTALL_PARSE_FAILED_MANIFEST_MALFORMED: Failed parse during installPackageLI: /data/app/vmdl1207711244.tmp/base.apk (at Binary XML file line #168): <meta-data> requires an android:value or android:resource attribute Unable to install /var/folders/9g/4r7qgd5s1096hyk8r_nzsw940000gn/T/ apkSelect1137704977225312066/base-xxhdpi.apk,/var/folders/9g/ 4r7qgd5s1096hyk8r_nzsw940000gn/T/apkSelect1137704977225312066/base-master.apk,/var/ folders/9g/4r7qgd5s1096hyk8r_nzsw940000gn/T/apkSelect1137704977225312066/base- en.apk,/var/folders/9g/4r7qgd5s1096hyk8r_nzsw940000gn/T/apkSelect1137704977225312066/ base-arm64_v8a.apk com.android.ddmlib.InstallException: Failed to commit install session 1207711244 with command cmd package install-commit 1207711244. Error: INSTALL_PARSE_FAILED_MANIFEST_MALFORMED: Failed parse during installPackageLI: /data/ app/vmdl1207711244.tmp/base.apk (at Binary XML file line #168): <meta-data> requires an android:value or android:resource attribute
60. <provider android:name="com.withpersona.sdk2.inquiry.document.DocumentFileProvider" android:exported="false" android:authorities="com.squareup.cash.beta.debug.persona.provider" android:grantUriPermissions="true" tools:node="remove"> </provider>
61. Gotcha 3 Resources
62. Execution failed for task ':cash-os:processInternalDebugResources'. > A failure occurred while executing com.android.build.gradle.internal.res.LinkApplicationAndroidResourcesTask$TaskAction > Android resource linking failed warn: removing resource com.squareup.cash.beta.debug:string/ pi2_governmentid_back_button without required default value. /Users/astrong/Development/Android/cash-android/cash-os/build/intermediates/ packaged_manifests/internalDebug/AndroidManifest.xml:1479: error: resource style/ Theme.PlayCore.Transparent (aka com.squareup.cash.beta.debug:style/ Theme.PlayCore.Transparent) not found. error: failed processing manifest.
63. <resources> <!-- This whole file is just to make manifest merging work for feature modules --> <!-- See https://medium.com/androiddevelopers/a-patchwork-plaid-monolith-to- modularized-app-60235d9f212e --> <style name="Theme.PlayCore.Transparent" /> </resources>
64. Boxapp
65. boxapp cashapp application library dynamic feature api Implements
66. boxapp plugins { alias(libs.plugins.android.application) alias(libs.plugins.kotlin.android) } android { namespace "app.cash.boxapp" dynamicFeatures = [":app"] }
67. boxapp public interface BoxAppFeature { @Composable public fun Tile() }
68. boxapp Row(modifier = Modifier.weight(1f)) { Column( modifier = Modifier.padding(10.dp), verticalArrangement = Arrangement.spacedBy(10.dp) ) { boxFeatures().forEach { it.Tile() } } }
69. boxapp cashapp application library dynamic feature api Implements
70. boxapp cashapp application library dynamic feature api Implements
71. cashapp class CashFeature : BoxAppFeature { private val navigator get() = Navigator.INSTANCE @Composable override fun Tile() { Box( Modifier .size(width = 200.dp, height = 60.dp) .background(Color(255, 222, 133)) .padding(20.dp) .clickable { navigator.startActivity( "com.squareup.cash.beta.debug", "com.squareup.cash.ui.MainActivity" ) } ) { Text("Cash App!") } } }
72. cashapp class CashFeature : BoxAppFeature { private val navigator get() = Navigator.INSTANCE @Composable override fun Tile() { Box( Modifier .size(width = 200.dp, height = 60.dp) .background(Color(255, 222, 133)) .padding(20.dp) .clickable { navigator.startActivity( "com.squareup.cash.beta.debug", "com.squareup.cash.ui.MainActivity" ) } ) { Text("Cash App!") } } }
73. boxapp cashapp application library dynamic feature api Implements
74. boxapp cashapp application library dynamic feature api Implements
75. boxapp Row(modifier = Modifier.weight(1f)) { Column( modifier = Modifier.padding(10.dp), verticalArrangement = Arrangement.spacedBy(10.dp) ) { boxFeatures().forEach { it.Tile() } } }
76. boxapp Row(modifier = Modifier.weight(1f)) { Column( modifier = Modifier.padding(10.dp), verticalArrangement = Arrangement.spacedBy(10.dp) ) { arrayOf( Class.forName("com.squareup.cash.CashFeature").newInstance() as BoxAppFeature, ) .forEach { it.Tile() } } }
78. boxapp cashapp application library dynamic feature api Implements
79. boxapp cashapp application library dynamic feature api Implements feature
80. feature class BigBoxFeature : BoxAppFeature { private val navigator get() = Navigator.INSTANCE @Composable override fun Tile() { Box( Modifier .size(width = 200.dp, height = 60.dp) .background(Color(255, 222, 133)) .padding(20.dp) .clickable { navigator.goTo { BigBoxScreen() } } ) { Text("Big Box Feature!") } } }
82. boxapp cashapp application library dynamic feature api Implements feature
83. boxapp cashapp application library dynamic feature api Implements feature feature:api
84. feature:api interface BigBoxMainScreen { fun registerWidget(widget: @Composable () -> Unit) }
85. boxapp cashapp application library dynamic feature api Implements feature feature:api
86. boxapp cashapp application library dynamic feature api Implements feature feature:api
87. boxapp cashapp application library dynamic feature api Implements feature feature:api
88. feature internal class BigBoxScreen @Inject constructor() : BigBoxMainScreen { val widgets = mutableListOf<@Composable () -> Unit>() override fun registerWidget(widget: @Composable () -> Unit) { widgets.add(widget) } @Composable fun view() { Column() { Spacer(modifier = Modifier.weight(1f)) Text(text = "Big Box Main Screen!") Spacer(modifier = Modifier.weight(1f)) widgets.forEach { it() Spacer(modifier = Modifier.weight(1f)) } } } }
89. feature internal class BigBoxScreen @Inject constructor() : BigBoxMainScreen { val widgets = mutableListOf<@Composable () -> Unit>() override fun registerWidget(widget: @Composable () -> Unit) { widgets.add(widget) } @Composable fun view() { Column() { Spacer(modifier = Modifier.weight(1f)) Text(text = "Big Box Main Screen!") Spacer(modifier = Modifier.weight(1f)) widgets.forEach { it() Spacer(modifier = Modifier.weight(1f)) } } } }
90. boxapp interface FeatureInterfaces { fun <T> whenInstalled(service: (T) -> Unit) fun <T> install(service: T) }
91. cashapp class CashApp : Application { @Inject lateinit var featureInterfaces: FeatureInterfaces override fun onCreate() { featureInterfaces.whenInstalled<BigBoxMainScreen> { it.registerWidget { MooncakeTheme( theme = this.moonCakeLight() ) { BalanceBox( instrumentManager, moneyFormatterFactory.createStandard(), ) } } } }
92. cashapp class CashApp : Application { @Inject lateinit var featureInterfaces: FeatureInterfaces override fun onCreate() { featureInterfaces.whenInstalled<BigBoxMainScreen> { it.registerWidget { MooncakeTheme( theme = this.moonCakeLight() ) { BalanceBox( instrumentManager, moneyFormatterFactory.createStandard(), ) } } } }
93. cashapp class CashFeature : BoxAppFeature { private val navigator get() = Navigator.INSTANCE @Composable override fun Tile() { Box( Modifier .size(width = 200.dp, height = 60.dp) .background(Color(255, 222, 133)) .padding(20.dp) .clickable { navigator.startActivity( "com.squareup.cash.beta.debug", "com.squareup.cash.ui.MainActivity" ) } ) { Text("Cash App!") } } }
94. cashapp class CashFeature @Inject constructor( private val navigator: Navigator ) : BoxAppFeature { @Composable override fun Tile() { Box( Modifier .size(width = 200.dp, height = 60.dp) .background(Color(255, 222, 133)) .padding(20.dp) .clickable { navigator.startActivity( "com.squareup.cash.beta.debug", "com.squareup.cash.ui.MainActivity" ) } ) { Text("Cash App!") } } }
95. boxapp @Component( modules = [BoxModule::class] ) interface BoxComponent { fun navigator(): Navigator fun featureInterfaces(): FeatureInterfaces @Component.Builder interface Builder { @BindsInstance fun navigator(navigator: Navigator): Builder fun build(): BoxComponent } }
96. boxapp public val component = DaggerBoxComponent.builder() .navigator(this) .build()
97. cashapp @Component( dependencies = [BoxComponent::class] )
98. boxapp public interface FeatureEntry { fun start() }
99. feature class BigBoxEntry( private val component: BoxComponent ): FeatureEntry { @Inject internal lateinit var featureRegistry: FeatureRegistry @Inject internal lateinit var bigBoxScreen: BigBoxScreen @Inject internal lateinit var featureInterfaces: FeatureInterfaces override fun start() { val bigBoxComponent = DaggerBigBoxComponent.builder() .boxComponent(component) .build() bigBoxComponent.inject(this) featureInterfaces.install<BigBoxMainScreen>(bigBoxScreen) featureRegistry.register(bigBoxComponent.bigBoxFeature()) } }
100. feature class BigBoxEntry( private val component: BoxComponent ): FeatureEntry { @Inject internal lateinit var featureRegistry: FeatureRegistry @Inject internal lateinit var bigBoxScreen: BigBoxScreen @Inject internal lateinit var featureInterfaces: FeatureInterfaces override fun start() { val bigBoxComponent = DaggerBigBoxComponent.builder() .boxComponent(component) .build() bigBoxComponent.inject(this) featureInterfaces.install<BigBoxMainScreen>(bigBoxScreen) featureRegistry.register(bigBoxComponent.bigBoxFeature()) } }
101. feature class BigBoxEntry( private val component: BoxComponent ): FeatureEntry { @Inject internal lateinit var featureRegistry: FeatureRegistry @Inject internal lateinit var bigBoxScreen: BigBoxScreen @Inject internal lateinit var featureInterfaces: FeatureInterfaces override fun start() { val bigBoxComponent = DaggerBigBoxComponent.builder() .boxComponent(component) .build() bigBoxComponent.inject(this) featureInterfaces.install<BigBoxMainScreen>(bigBoxScreen) featureRegistry.register(bigBoxComponent.bigBoxFeature()) } }
102. boxapp override fun onCreate(savedInstanceState: Bundle?) { features.forEach { it.newInstance(component).start() } } private val features = arrayOf( Class.forName(“app.cash.boxapp.bigboxfeature.BigBoxEntry"), Class.forName(“app.cash.CashAppEntry") ).map { @Suppress("UNCHECKED_CAST") it.getConstructor(BoxComponent::class.java) as Constructor<FeatureEntry> }
103. boxapp <manifest xmlns:android="http://schemas.android.com/apk/res/android" xmlns:dist="http://schemas.android.com/apk/distribution"> <dist:module dist:instant="false" dist:title="@string/smallboxfeature_title"> <dist:delivery> <dist:install-time /> </dist:delivery> <dist:fusing dist:include="true" /> </dist:module> </manifest>
104. boxapp <manifest xmlns:android="http://schemas.android.com/apk/res/android" xmlns:dist="http://schemas.android.com/apk/distribution"> <dist:module dist:instant="false" dist:title="@string/smallboxfeature_title"> <dist:delivery> <dist:on-demand /> </dist:delivery> <dist:fusing dist:include="true" /> </dist:module> </manifest>
105. boxapp val splitInstallManager = SplitInstallManagerFactory.create(context) val request = SplitInstallRequest .newBuilder() .addModule("big-box-feature") .build() var mySessionId = 0 splitInstallManager .startInstall(request) .addOnSuccessListener { sessionId -> mySessionId = sessionId } .addOnFailureListener { exception -> ... }
106. boxapp val listener = SplitInstallStateUpdatedListener { state -> if (state.sessionId() == mySessionId && state.status() == INSTALLED) { (Class.forName("app.cash.boxapp.bigboxfeature.BigBoxEntry") .getConstructor(BoxComponent::class.java) as Constructor<FeatureEntry>) .newInstance(component).start() } } splitInstallManager.registerListener(listener)
108. boxapp cashapp application library dynamic feature api Implements feature feature:api entity-sync
109. " Focus " https://github.com/dropbox/focus
110. boxapp plugins { alias(libs.plugins.android.application) alias(libs.plugins.kotlin.android) } android { namespace "app.cash.boxapp" dynamicFeatures = [ // ":app", ":bigboxfeature", ] }
111. boxapp > ./gradlew :bigboxfeature:focus
113. boxapp cashapp application library dynamic feature api Implements feature feature:api entity-sync
114. boxapp application library dynamic feature api Implements feature feature:api entity-sync cashapp
115. Thanks! @strongolopolis