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Writing backwards compatible Gradle plugins Simon Schiller ● droidcon Berlin 2022 simonxschiller simonschiller simonschiller.io

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Gradle plugins ● Fundamental building blocks of Gradle ● Used to customize and extend build logic ● Plugins typically interact with other plugins

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Writing Gradle plugins class SamplePlugin : Plugin { override fun apply(project: Project) { // Plugin logic } }

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Writing Gradle plugins class SamplePlugin : Plugin { override fun apply(project: Project) { // Plugin logic } } # Located under META-INF/gradle-plugins/com.droidcon.sample.properties implementation-class=com.droidcon.sample.SamplePlugin

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Interacting with other plugins // To interact with AGP we need a dependency on AGP dependencies { implementation("com.android.tools.build:gradle:7.0.0") }

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Resources around writing Gradle plugins ● Using Gradle Plugins ● Developing Custom Gradle Plugins ● Extend the Android Gradle plugin ● Gradle and AGP Build APIs - How to write a plugin

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Backwards compatibility

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Example - Manifest printing plugin plugins { id("com.droidcon.sample") version "1.0.0" id("com.android.application") version "7.0.0" }

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Example - Manifest printing plugin plugins { id("com.droidcon.sample") version "1.0.0" id("com.android.application") version "7.0.0" } > ./gradlew printReleaseManifest > > > package="com.droidcon.sample" > > > > >

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Backwards compatibility com.droidcon.sample 󰳕 AGP 7.0.0

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Backwards compatibility com.droidcon.sample 󰳕 AGP 7.0.0 󰞵 AGP 4.2.0 󰠁 AGP 4.1.0

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Backwards compatibility id("com.android.application") version "7.0.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { isMinifyEnabled = true } } }

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Backwards compatibility id("com.android.application") version "7.0.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { isMinifyEnabled = true } } }

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Backwards compatibility id("com.android.application") version "7.0.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { isMinifyEnabled = true } } }

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Backwards compatibility id("com.android.application") version "7.0.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { isMinifyEnabled = true } } } > ./gradlew printReleaseManifest > > >

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Backwards compatibility id("com.android.application") version "7.0.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { isMinifyEnabled = true } } } id("com.android.application") version "4.2.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { minifyEnabled(true) } } }

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Backwards compatibility id("com.android.application") version "7.0.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { isMinifyEnabled = true } } } id("com.android.application") version "4.2.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { minifyEnabled(true) } } }

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Backwards compatibility id("com.android.application") version "7.0.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { isMinifyEnabled = true } } } id("com.android.application") version "4.2.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { minifyEnabled(true) } } } > ./gradlew printReleaseManifest > > Script compilation error: > minifyEnabled(true) > ^ Unresolved reference: minifyEnabled

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What is happening? project com.droidcon.sample com.android.application 4.2.0

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What is happening? project com.droidcon.sample com.android.application com.android.application 7.0.0 4.2.0

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What is happening? project com.droidcon.sample com.android.application com.android.application 7.0.0 4.2.0

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What is happening? project com.droidcon.sample com.android.application com.android.application 7.0.0 4.2.0

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What is happening? // In our com.droidcon.sample plugin dependencies { implementation("com.android.tools.build:gradle:7.0.0") } project com.droidcon.sample com.android.application com.android.application 7.0.0 4.2.0 com.android.tools.build gradle 7.0.0

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How to resolve it // In our com.droidcon.sample plugin dependencies { compileOnly("com.android.tools.build:gradle:7.0.0") } project com.droidcon.sample com.android.application 4.2.0

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How to resolve it // In our com.droidcon.sample plugin dependencies { compileOnly("com.android.tools.build:gradle:7.0.0") } project com.droidcon.sample com.android.application 4.2.0

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How to resolve it // In the plugin code project.plugins.withId("com.android.application") { // Code interacting with the Android Gradle plugin }

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Does it work now? id("com.android.application") version "7.0.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { isMinifyEnabled = true } } } id("com.android.application") version "4.2.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { minifyEnabled(true) } } }

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Does it work now? id("com.android.application") version "7.0.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { isMinifyEnabled = true } } } id("com.android.application") version "4.2.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { minifyEnabled(true) } } } > ./gradlew printReleaseManifest > > >

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Does it work now? id("com.android.application") version "7.0.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { isMinifyEnabled = true } } } id("com.android.application") version "4.2.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { minifyEnabled(true) } } } > ./gradlew printReleaseManifest > > > > ./gradlew printReleaseManifest > > FAILURE: Build failed with an exception > > * Exception is: > java.lang.NoClassDefFoundError: ...

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The problem Version A sample.Foo.foo() sample.Bar.bar() sample.Baz.baz() Version B sample.Foo.foo() sample.Bar.change() sample.Baz.baz() Version C sample.Foo.change() sample.Bar.change() sample.Baz.baz()

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Locating the merged manifest - AGP 4.1.0 import com.android.build.api.artifact.ArtifactType import com.android.build.api.dsl.ApplicationExtension val extension = project.extensions.getByType(ApplicationExtension::class.java) extension.onVariantProperties { variant -> val manifest = variant.artifacts.get(ArtifactType.MERGED_MANIFEST) // Do something with the manifest }

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Locating the merged manifest - AGP 4.1.0 import com.android.build.api.artifact.ArtifactType import com.android.build.api.dsl.ApplicationExtension val extension = project.extensions.getByType(ApplicationExtension::class.java) extension.onVariantProperties { variant -> val manifest = variant.artifacts.get(ArtifactType.MERGED_MANIFEST) // Do something with the manifest }

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Locating the merged manifest - AGP 4.1.0 import com.android.build.api.artifact.ArtifactType import com.android.build.api.dsl.ApplicationExtension val extension = project.extensions.getByType(ApplicationExtension::class.java) extension.onVariantProperties { variant -> val manifest = variant.artifacts.get(ArtifactType.MERGED_MANIFEST) // Do something with the manifest }

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Locating the merged manifest - AGP 4.1.0 import com.android.build.api.artifact.ArtifactType import com.android.build.api.dsl.ApplicationExtension val extension = project.extensions.getByType(ApplicationExtension::class.java) extension.onVariantProperties { variant -> val manifest = variant.artifacts.get(ArtifactType.MERGED_MANIFEST) // Do something with the manifest }

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Locating the merged manifest - AGP 4.2.0 import com.android.build.api.artifact.ArtifactType import com.android.build.api.extension.AndroidComponentsExtension val extension = project.extensions.getByType(AndroidComponentsExtension::class.java) extension.onVariants { variant -> val manifest = variant.artifacts.get(ArtifactType.MERGED_MANIFEST) // Do something with the manifest }

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Locating the merged manifest - AGP 4.2.0 import com.android.build.api.artifact.ArtifactType import com.android.build.api.extension.AndroidComponentsExtension val extension = project.extensions.getByType(AndroidComponentsExtension::class.java) extension.onVariants { variant -> val manifest = variant.artifacts.get(ArtifactType.MERGED_MANIFEST) // Do something with the manifest }

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Locating the merged manifest - AGP 7.0.0 import com.android.build.api.artifact.SingleArtifact import com.android.build.api.variant.AndroidComponentsExtension val extension = project.extensions.getByType(AndroidComponentsExtension::class.java) extension.onVariants { variant -> val manifest = variant.artifacts.get(SingleArtifact.MERGED_MANIFEST) // Do something with the manifest }

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Locating the merged manifest - AGP 7.0.0 import com.android.build.api.artifact.SingleArtifact import com.android.build.api.variant.AndroidComponentsExtension val extension = project.extensions.getByType(AndroidComponentsExtension::class.java) extension.onVariants { variant -> val manifest = variant.artifacts.get(SingleArtifact.MERGED_MANIFEST) // Do something with the manifest }

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Which version are we running against? Run code specific to A Run code specific to B Run code specific to C How to resolve it A B C

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Which version are we running against? Run code specific to A Run code specific to B Run code specific to C How to resolve it A B C

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1. Android Gradle plugin APIs import com.android.Version val version = Version.ANDROID_GRADLE_PLUGIN_VERSION // 7.0.0 return VersionNumber.parse(version)

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1. Android Gradle plugin APIs import com.android.Version val version = Version.ANDROID_GRADLE_PLUGIN_VERSION // 7.0.0 return VersionNumber.parse(version) // In your build.gradle.kts compileOnly("com.android.tools:common:30.0.0")

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2. Gradle APIs // Get all resolved Gradle classpath dependencies val buildscript = project.rootProject.buildscript val config = buildscript.configurations.getByName("classpath") val artifacts = config.resolvedConfiguration.resolvedArtifacts // Find the Android Gradle plugin dependency val androidGradlePlugin = artifacts.singleOrNull { it.moduleVersion.id.toString().startsWith("com.android.tools.build:gradle:") } ?: error("Could not determine Android Gradle plugin version") // Extract the resolved Android Gradle plugin version val version = androidGradlePlugin.moduleVersion.id.version // 7.0.0 return VersionNumber.parse(version)

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2. Gradle APIs // Get all resolved Gradle classpath dependencies val buildscript = project.rootProject.buildscript val config = buildscript.configurations.getByName("classpath") val artifacts = config.resolvedConfiguration.resolvedArtifacts // Find the Android Gradle plugin dependency val androidGradlePlugin = artifacts.singleOrNull { it.moduleVersion.id.toString().startsWith("com.android.tools.build:gradle:") } ?: error("Could not determine Android Gradle plugin version") // Extract the resolved Android Gradle plugin version val version = androidGradlePlugin.moduleVersion.id.version // 7.0.0 return VersionNumber.parse(version)

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2. Gradle APIs // Get all resolved Gradle classpath dependencies val buildscript = project.rootProject.buildscript val config = buildscript.configurations.getByName("classpath") val artifacts = config.resolvedConfiguration.resolvedArtifacts // Find the Android Gradle plugin dependency val androidGradlePlugin = artifacts.singleOrNull { it.moduleVersion.id.toString().startsWith("com.android.tools.build:gradle:") } ?: error("Could not determine Android Gradle plugin version") // Extract the resolved Android Gradle plugin version val version = androidGradlePlugin.moduleVersion.id.version // 7.0.0 return VersionNumber.parse(version)

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2. Gradle APIs // Get all resolved Gradle classpath dependencies val buildscript = project.rootProject.buildscript val config = buildscript.configurations.getByName("classpath") val artifacts = config.resolvedConfiguration.resolvedArtifacts // Find the Android Gradle plugin dependency val androidGradlePlugin = artifacts.singleOrNull { it.moduleVersion.id.toString().startsWith("com.android.tools.build:gradle:") } ?: error("Could not determine Android Gradle plugin version") // Extract the resolved Android Gradle plugin version val version = androidGradlePlugin.moduleVersion.id.version // 7.0.0 return VersionNumber.parse(version)

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Which version are we running against? Run code specific to A Run code specific to B Run code specific to C How to resolve it A B C

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Different code for different versions val callback = Action> { manifest -> // Do something with the manifest } // Call the correct code depending on the available version val version = getAndroidGradlePluginVersion(project) when { version < VersionNumber.parse("4.1.0") -> error("Unsupported AGP version") version < VersionNumber.parse("4.2.0") -> handle4Dot1(project, callback) version < VersionNumber.parse("7.0.0") -> handle4Dot2(project, callback) else -> handle7Dot0(project, callback) }

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Different code for different versions val callback = Action> { manifest -> // Do something with the manifest } // Call the correct code depending on the available version val version = getAndroidGradlePluginVersion(project) when { version < VersionNumber.parse("4.1.0") -> error("Unsupported AGP version") version < VersionNumber.parse("4.2.0") -> handle4Dot1(project, callback) version < VersionNumber.parse("7.0.0") -> handle4Dot2(project, callback) else -> handle7Dot0(project, callback) }

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Different code for different versions val callback = Action> { manifest -> // Do something with the manifest } // Call the correct code depending on the available version val version = getAndroidGradlePluginVersion(project) when { version < VersionNumber.parse("4.1.0") -> error("Unsupported AGP version") version < VersionNumber.parse("4.2.0") -> handle4Dot1(project, callback) version < VersionNumber.parse("7.0.0") -> handle4Dot2(project, callback) else -> handle7Dot0(project, callback) }

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Different code for different versions val callback = Action> { manifest -> // Do something with the manifest } // Call the correct code depending on the available version val version = getAndroidGradlePluginVersion(project) when { version < VersionNumber.parse("4.1.0") -> error("Unsupported AGP version") version < VersionNumber.parse("4.2.0") -> handle4Dot1(project, callback) version < VersionNumber.parse("7.0.0") -> handle4Dot2(project, callback) else -> handle7Dot0(project, callback) }

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Different code for different versions val callback = Action> { manifest -> // Do something with the manifest } // Call the correct code depending on the available version val version = getAndroidGradlePluginVersion(project) when { version < VersionNumber.parse("4.1.0") -> error("Unsupported AGP version") version < VersionNumber.parse("4.2.0") -> handle4Dot1(project, callback) version < VersionNumber.parse("7.0.0") -> handle4Dot2(project, callback) else -> handle7Dot0(project, callback) }

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Different code for different versions val callback = Action> { manifest -> // Do something with the manifest } // Call the correct code depending on the available version val version = getAndroidGradlePluginVersion(project) when { version < VersionNumber.parse("4.1.0") -> error("Unsupported AGP version") version < VersionNumber.parse("4.2.0") -> handle4Dot1(project, callback) version < VersionNumber.parse("7.0.0") -> handle4Dot2(project, callback) else -> handle7Dot0(project, callback) }

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Different code for different versions val callback = Action> { manifest -> // Do something with the manifest } // Call the correct code depending on the available version val version = getAndroidGradlePluginVersion(project) when { version < VersionNumber.parse("4.1.0") -> error("Unsupported AGP version") version < VersionNumber.parse("4.2.0") -> handle4Dot1(project, callback) version < VersionNumber.parse("7.0.0") -> handle4Dot2(project, callback) else -> handle7Dot0(project, callback) }

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Different code for different versions val callback = Action> { manifest -> // Do something with the manifest } // Call the correct code depending on the available version val version = getAndroidGradlePluginVersion(project) when { version < VersionNumber.parse("4.1.0") -> error("Unsupported AGP version") version < VersionNumber.parse("4.2.0") -> handle4Dot1(project, callback) version < VersionNumber.parse("7.0.0") -> handle4Dot2(project, callback) else -> handle7Dot0(project, callback) } compileOnly("com.android.tools.build:gradle:4.1.0")

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Different code for different versions val callback = Action> { manifest -> // Do something with the manifest } // Call the correct code depending on the available version val version = getAndroidGradlePluginVersion(project) when { version < VersionNumber.parse("4.1.0") -> error("Unsupported AGP version") version < VersionNumber.parse("4.2.0") -> handle4Dot1(project, callback) version < VersionNumber.parse("7.0.0") -> handle4Dot2(project, callback) else -> handle7Dot0(project, callback) } compileOnly("com.android.tools.build:gradle:4.2.0")

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1. Reflection

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1. Reflection // Compatibility code for Android Gradle plugin 4.1.0 val android = project.extensions.getByName("android") val method = android::class.java.getMethod("onVariantProperties", Action::class.java) method.invoke(android, Action { variant -> val className = "com.android.build.api.artifact.ArtifactType" val enumClass = Class.forName("$className\$MERGED_MANIFEST") val enumInstance = enumClass.getField("INSTANCE").get(null) val artifacts = variant::class.java.getMethod("getArtifacts").invoke(variant) val getMethod = artifacts::class.java.getMethod("get", Class.forName(className)) val manifest = getMethod.invoke(artifacts, enumInstance) callback.execute(manifest) })

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1. Reflection // Compatibility code for Android Gradle plugin 4.1.0 val android = project.extensions.getByName("android") val method = android::class.java.getMethod("onVariantProperties", Action::class.java) method.invoke(android, Action { variant -> val className = "com.android.build.api.artifact.ArtifactType" val enumClass = Class.forName("$className\$MERGED_MANIFEST") val enumInstance = enumClass.getField("INSTANCE").get(null) val artifacts = variant::class.java.getMethod("getArtifacts").invoke(variant) val getMethod = artifacts::class.java.getMethod("get", Class.forName(className)) val manifest = getMethod.invoke(artifacts, enumInstance) callback.execute(manifest) })

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1. Reflection // Compatibility code for Android Gradle plugin 4.1.0 val android = project.extensions.getByName("android") val method = android::class.java.getMethod("onVariantProperties", Action::class.java) method.invoke(android, Action { variant -> val className = "com.android.build.api.artifact.ArtifactType" val enumClass = Class.forName("$className\$MERGED_MANIFEST") val enumInstance = enumClass.getField("INSTANCE").get(null) val artifacts = variant::class.java.getMethod("getArtifacts").invoke(variant) val getMethod = artifacts::class.java.getMethod("get", Class.forName(className)) val manifest = getMethod.invoke(artifacts, enumInstance) callback.execute(manifest) })

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1. Reflection // Compatibility code for Android Gradle plugin 4.1.0 val android = project.extensions.getByName("android") val method = android::class.java.getMethod("onVariantProperties", Action::class.java) method.invoke(android, Action { variant -> val className = "com.android.build.api.artifact.ArtifactType" val enumClass = Class.forName("$className\$MERGED_MANIFEST") val enumInstance = enumClass.getField("INSTANCE").get(null) val artifacts = variant::class.java.getMethod("getArtifacts").invoke(variant) val getMethod = artifacts::class.java.getMethod("get", Class.forName(className)) val manifest = getMethod.invoke(artifacts, enumInstance) callback.execute(manifest) })

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1. Reflection // Compatibility code for Android Gradle plugin 4.1.0 val android = project.extensions.getByName("android") val method = android::class.java.getMethod("onVariantProperties", Action::class.java) method.invoke(android, Action { variant -> val className = "com.android.build.api.artifact.ArtifactType" val enumClass = Class.forName("$className\$MERGED_MANIFEST") val enumInstance = enumClass.getField("INSTANCE").get(null) val artifacts = variant::class.java.getMethod("getArtifacts").invoke(variant) val getMethod = artifacts::class.java.getMethod("get", Class.forName(className)) val manifest = getMethod.invoke(artifacts, enumInstance) callback.execute(manifest) })

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2. Groovy

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2. Groovy // Compatibility code in src/main/groovy/Compat.groovy class Compat { static void handle4Dot1(Project project, Action callback) { project.android.onVariantProperties { variant -> def manifest = variant.artifacts.get(ArtifactType.MERGED_MANIFEST) callback.execute(manifest) } } static void handle4Dot2(Project project, Action callback) { ... } static void handle7Dot0(Project project, Action callback) { ... } }

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// Compatibility code in src/main/groovy/Compat.groovy class Compat { static void handle4Dot1(Project project, Action callback) { project.android.onVariantProperties { variant -> def manifest = variant.artifacts.get(ArtifactType.MERGED_MANIFEST) callback.execute(manifest) } } static void handle4Dot2(Project project, Action callback) { ... } static void handle7Dot0(Project project, Action callback) { ... } } 2. Groovy

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2. Groovy // Compatibility code in src/main/groovy/Compat.groovy class Compat { static void handle4Dot1(Project project, Action callback) { project.android.onVariantProperties { variant -> def manifest = variant.artifacts.get(ArtifactType.MERGED_MANIFEST) callback.execute(manifest) } } static void handle4Dot2(Project project, Action callback) { ... } static void handle7Dot0(Project project, Action callback) { ... } }

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2. Groovy // Compatibility code in src/main/groovy/Compat.groovy class Compat { static void handle4Dot1(Project project, Action callback) { project.android.onVariantProperties { variant -> def manifest = variant.artifacts.get(ArtifactType.MERGED_MANIFEST) callback.execute(manifest) } } static void handle4Dot2(Project project, Action callback) { ... } static void handle7Dot0(Project project, Action callback) { ... } }

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// Compatibility code in src/main/groovy/Compat.groovy class Compat { static void handle4Dot1(Project project, Action callback) { project.android.onVariantProperties { variant -> def manifest = variant.artifacts.get(ArtifactType.MERGED_MANIFEST) callback.execute(manifest) } } static void handle4Dot2(Project project, Action callback) { ... } static void handle7Dot0(Project project, Action callback) { ... } } 2. Groovy

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2. Groovy // In your build.gradle.kts plugins { id("org.gradle.groovy") } // Include dependencies in the Groovy classpath tasks.withType { classpath = sourceSets.main.get().compileClasspath } // Include compiled Groovy classes in the Kotlin classpath tasks.withType { classpath += files(sourceSets.main.get().groovy.classesDirectory) }

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2. Groovy // In your build.gradle.kts plugins { id("org.gradle.groovy") } // Include dependencies in the Groovy classpath tasks.withType { classpath = sourceSets.main.get().compileClasspath } // Include compiled Groovy classes in the Kotlin classpath tasks.withType { classpath += files(sourceSets.main.get().groovy.classesDirectory) } groovy

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// In your build.gradle.kts plugins { id("org.gradle.groovy") } // Include dependencies in the Groovy classpath tasks.withType { classpath = sourceSets.main.get().compileClasspath } // Include compiled Groovy classes in the Kotlin classpath tasks.withType { classpath += files(sourceSets.main.get().groovy.classesDirectory) } 2. Groovy groovy dependencies

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// In your build.gradle.kts plugins { id("org.gradle.groovy") } // Include dependencies in the Groovy classpath tasks.withType { classpath = sourceSets.main.get().compileClasspath } // Include compiled Groovy classes in the Kotlin classpath tasks.withType { classpath += files(sourceSets.main.get().groovy.classesDirectory) } 2. Groovy kotlin groovy dependencies

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3. Compile against multiple versions

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3. Compile against multiple versions val callback = Action> { manifest -> // Do something with the manifest } // Call the correct code depending on the available version val version = getAndroidGradlePluginVersion(project) when { version < VersionNumber.parse("4.1.0") -> error("Unsupported AGP version") version < VersionNumber.parse("4.2.0") -> handle4Dot1(project, callback) version < VersionNumber.parse("7.0.0") -> handle4Dot2(project, callback) else -> handle7Dot0(project, callback) } compileOnly("com.android.tools.build:gradle:4.1.0")

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3. Compile against multiple versions src/ │ ├─ main/ │ ├─ AndroidManifest.xml │ └─ kotlin/.../ │ ├─ debug/ │ ├─ AndroidManifest.xml │ └─ kotlin/.../ │ └─ release/ ├─ AndroidManifest.xml └─ kotlin/.../

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3. Compile against multiple versions src/ │ ├─ main/ │ ├─ AndroidManifest.xml │ └─ kotlin/.../ │ ├─ debug/ │ ├─ AndroidManifest.xml │ └─ kotlin/.../ │ └─ release/ ├─ AndroidManifest.xml └─ kotlin/.../

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3. Compile against multiple versions src/ │ ├─ main/ │ ├─ AndroidManifest.xml │ └─ kotlin/.../ │ ├─ debug/ │ ├─ AndroidManifest.xml │ └─ kotlin/.../ │ └─ release/ ├─ AndroidManifest.xml └─ kotlin/.../

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3. Compile against multiple versions src/ │ ├─ main/ │ ├─ AndroidManifest.xml │ └─ kotlin/.../ │ ├─ debug/ │ ├─ AndroidManifest.xml │ └─ kotlin/.../ │ └─ release/ ├─ AndroidManifest.xml └─ kotlin/.../ src/ │ ├─ main/kotlin/.../ │ └─ SamplePlugin.kt │ ├─ compat4Dot1/kotlin/.../ │ └─ Compat4Dot1.kt │ ├─ compat4Dot2/kotlin/.../ │ └─ Compat4Dot2.kt │ └─ compat7Dot0/kotlin/.../ └─ Compat7Dot0.kt

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3. Compile against multiple versions src/ │ ├─ main/ │ ├─ AndroidManifest.xml │ └─ kotlin/.../ │ ├─ debug/ │ ├─ AndroidManifest.xml │ └─ kotlin/.../ │ └─ release/ ├─ AndroidManifest.xml └─ kotlin/.../ src/ │ ├─ main/kotlin/.../ │ └─ SamplePlugin.kt │ ├─ compat4Dot1/kotlin/.../ │ └─ Compat4Dot1.kt │ ├─ compat4Dot2/kotlin/.../ │ └─ Compat4Dot2.kt │ └─ compat7Dot0/kotlin/.../ └─ Compat7Dot0.kt

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3. Compile against multiple versions src/ │ ├─ main/ │ ├─ AndroidManifest.xml │ └─ kotlin/.../ │ ├─ debug/ │ ├─ AndroidManifest.xml │ └─ kotlin/.../ │ └─ release/ ├─ AndroidManifest.xml └─ kotlin/.../ src/ │ ├─ main/kotlin/.../ │ └─ SamplePlugin.kt │ ├─ compat4Dot1/kotlin/.../ │ └─ Compat4Dot1.kt │ ├─ compat4Dot2/kotlin/.../ │ └─ Compat4Dot2.kt │ └─ compat7Dot0/kotlin/.../ └─ Compat7Dot0.kt

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3. Compile against multiple versions // Compatibility code in src/compat4Dot1/kotlin/Compat4Dot1.kt fun handle4Dot1(project: Project, callback: Action>) { val extension = project.extensions.getByType(ApplicationExtension::class.java) extension.onVariantProperties { variant -> val manifest = variant.artifacts.get(ArtifactType.MERGED_MANIFEST) callback.execute(manifest) } } // Compatibility code in src/compat4Dot2/kotlin/Compat4Dot2.kt fun handle4Dot2(project: Project, callback: Action>) { ... } // Compatibility code in src/compat7Dot0/kotlin/Compat7Dot0.kt fun handle7Dot0(project: Project, callback: Action>) { ... }

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3. Compile against multiple versions // Compatibility code in src/compat4Dot1/kotlin/Compat4Dot1.kt fun handle4Dot1(project: Project, callback: Action>) { val extension = project.extensions.getByType(ApplicationExtension::class.java) extension.onVariantProperties { variant -> val manifest = variant.artifacts.get(ArtifactType.MERGED_MANIFEST) callback.execute(manifest) } } // Compatibility code in src/compat4Dot2/kotlin/Compat4Dot2.kt fun handle4Dot2(project: Project, callback: Action>) { ... } // Compatibility code in src/compat7Dot0/kotlin/Compat7Dot0.kt fun handle7Dot0(project: Project, callback: Action>) { ... }

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3. Compile against multiple versions // Compatibility code in src/compat4Dot1/kotlin/Compat4Dot1.kt fun handle4Dot1(project: Project, callback: Action>) { val extension = project.extensions.getByType(ApplicationExtension::class.java) extension.onVariantProperties { variant -> val manifest = variant.artifacts.get(ArtifactType.MERGED_MANIFEST) callback.execute(manifest) } } // Compatibility code in src/compat4Dot2/kotlin/Compat4Dot2.kt fun handle4Dot2(project: Project, callback: Action>) { ... } // Compatibility code in src/compat7Dot0/kotlin/Compat7Dot0.kt fun handle7Dot0(project: Project, callback: Action>) { ... }

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3. Compile against multiple versions // In your build.gradle.kts val compat4Dot1 by sourceSets.creating val compat4Dot2 by sourceSets.creating val compat7Dot0 by sourceSets.creating dependencies { compat4Dot1.compileOnlyConfigurationName("com.android.tools.build:gradle:4.1.0") compat4Dot2.compileOnlyConfigurationName("com.android.tools.build:gradle:4.2.0") compat7Dot0.compileOnlyConfigurationName("com.android.tools.build:gradle:7.0.0") ...

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// In your build.gradle.kts val compat4Dot1 by sourceSets.creating val compat4Dot2 by sourceSets.creating val compat7Dot0 by sourceSets.creating dependencies { compat4Dot1.compileOnlyConfigurationName("com.android.tools.build:gradle:4.1.0") compat4Dot2.compileOnlyConfigurationName("com.android.tools.build:gradle:4.2.0") compat7Dot0.compileOnlyConfigurationName("com.android.tools.build:gradle:7.0.0") ... 3. Compile against multiple versions compat4Dot2 compat4Dot1 compat7Dot0

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3. Compile against multiple versions // In your build.gradle.kts val compat4Dot1 by sourceSets.creating val compat4Dot2 by sourceSets.creating val compat7Dot0 by sourceSets.creating dependencies { compat4Dot1.compileOnlyConfigurationName("com.android.tools.build:gradle:4.1.0") compat4Dot2.compileOnlyConfigurationName("com.android.tools.build:gradle:4.2.0") compat7Dot0.compileOnlyConfigurationName("com.android.tools.build:gradle:7.0.0") ... compat4Dot2 compat4Dot1 compat7Dot0 AGP 4.2.0 AGP 4.1.0 AGP 7.0.0

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3. Compile against multiple versions ... compileOnly(compat4Dot1.output) compileOnly(compat4Dot2.output) compileOnly(compat7Dot0.output) } tasks.withType { from(compat4Dot1.output) from(compat4Dot2.output) from(compat7Dot0.output) } compat4Dot2 compat4Dot1 compat7Dot0 AGP 4.2.0 AGP 4.1.0 AGP 7.0.0 main

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... compileOnly(compat4Dot1.output) compileOnly(compat4Dot2.output) compileOnly(compat7Dot0.output) } tasks.withType { from(compat4Dot1.output) from(compat4Dot2.output) from(compat7Dot0.output) } com.droidcon.sample 3. Compile against multiple versions compat4Dot2 compat4Dot1 compat7Dot0 AGP 4.2.0 AGP 4.1.0 AGP 7.0.0 main

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3. Compile against multiple versions // Main code in src/main/kotlin/SamplePlugin.kt val version = getAndroidGradlePluginVersion(project) when { version < VersionNumber.parse("4.1.0") -> error("Unsupported AGP version") version < VersionNumber.parse("4.2.0") -> handle4Dot1(project, callback) version < VersionNumber.parse("7.0.0") -> handle4Dot2(project, callback) else -> handle7Dot0(project, callback) }

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Does it work now? id("com.android.application") version "7.0.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { isMinifyEnabled = true } } } id("com.android.application") version "4.2.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { minifyEnabled(true) } } }

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Does it work now? id("com.android.application") version "7.0.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { isMinifyEnabled = true } } } id("com.android.application") version "4.2.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { minifyEnabled(true) } } } > ./gradlew printReleaseManifest > > >

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Does it work now? id("com.android.application") version "7.0.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { isMinifyEnabled = true } } } id("com.android.application") version "4.2.0" id("com.droidcon.sample") version "1.0.0" android { buildTypes { named("release").configure { minifyEnabled(true) } } } > ./gradlew printReleaseManifest > > > > ./gradlew printReleaseManifest > > >

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Non-plugin dependencies

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Non-plugin dependencies your plugin dependency 1.2.0

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Non-plugin dependencies your plugin dependency 1.2.0 1.1.0 dependency another plugin

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Non-plugin dependencies your plugin dependency 1.2.0 1.1.0 dependency another plugin project

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Non-plugin dependencies your plugin dependency 1.2.0 1.1.0 dependency another plugin project

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Embedding dependencies Declaring dependencies your plugin dependency

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Embedding dependencies Declaring dependencies Embedding dependencies your plugin dependency your plugin dependency

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Embedding dependencies Declaring dependencies Embedding dependencies Also repackage classes: foo.Dependency -> plugin.foo.Dependency foo.bar.Other -> plugin.foo.bar.Other your plugin dependency your plugin dependency

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Embedding dependencies Declaring dependencies Embedding dependencies Also repackage classes: foo.Dependency -> plugin.foo.Dependency foo.bar.Other -> plugin.foo.bar.Other your plugin dependency See https://github.com/johnrengelman/shadow or https://github.com/GradleUp/gr8 for more details your plugin dependency

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Testing

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Testing against multiple versions # Example CI config for GitHub Actions jobs: verify: strategy: matrix: android-gradle-plugin: [ 4.1.0, 4.2.0, 7.0.0 ] steps: # ... - name: 'Run checks' env: ANDROID_GRADLE_PLUGIN_VERSION: ${{ matrix.android-gradle-plugin }} run: ./gradlew check --stacktrace # ... See https://docs.gradle.org/current/userguide/testing_gradle_plugins.html for more details

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Testing against multiple versions # Example CI config for GitHub Actions jobs: verify: strategy: matrix: android-gradle-plugin: [ 4.1.0, 4.2.0, 7.0.0 ] steps: # ... - name: 'Run checks' env: ANDROID_GRADLE_PLUGIN_VERSION: ${{ matrix.android-gradle-plugin }} run: ./gradlew check --stacktrace # ... See https://docs.gradle.org/current/userguide/testing_gradle_plugins.html for more details

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Testing against multiple versions # Example CI config for GitHub Actions jobs: verify: strategy: matrix: android-gradle-plugin: [ 4.1.0, 4.2.0, 7.0.0 ] steps: # ... - name: 'Run checks' env: ANDROID_GRADLE_PLUGIN_VERSION: ${{ matrix.android-gradle-plugin }} run: ./gradlew check --stacktrace # ... See https://docs.gradle.org/current/userguide/testing_gradle_plugins.html for more details

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Testing against multiple versions See https://docs.gradle.org/current/userguide/testing_gradle_plugins.html for more details

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What did we talk about? ● Backwards compatibility

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What did we talk about? ● Backwards compatibility ● Why it can be a problem

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What did we talk about? ● Backwards compatibility ● Why it can be a problem ● Determining the AGP version ○ Fields from AGP ○ Gradle APIs

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What did we talk about? ● Backwards compatibility ● Why it can be a problem ● Determining the AGP version ○ Fields from AGP ○ Gradle APIs ● Writing compatible code ○ Reflection ○ Groovy ○ Compiling against multiple versions

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What did we talk about? ● Backwards compatibility ● Why it can be a problem ● Determining the AGP version ○ Fields from AGP ○ Gradle APIs ● Writing compatible code ○ Reflection ○ Groovy ○ Compiling against multiple versions ● Non-plugin dependencies

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What did we talk about? ● Backwards compatibility ● Why it can be a problem ● Determining the AGP version ○ Fields from AGP ○ Gradle APIs ● Writing compatible code ○ Reflection ○ Groovy ○ Compiling against multiple versions ● Non-plugin dependencies ● Testing

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What did we talk about? ● Backwards compatibility ● Why it can be a problem ● Determining the AGP version ○ Fields from AGP ○ Gradle APIs ● Writing compatible code ○ Reflection ○ Groovy ○ Compiling against multiple versions ● Non-plugin dependencies ● Testing See https://github.com/simonschiller/manifestprinter for a sample project

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Writing backwards compatible Gradle plugins Simon Schiller ● droidcon Berlin 2022 simonxschiller simonschiller simonschiller.io