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@vRallev
Last active July 7, 2025 16:33
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Gradle tasks to detect changes in the merged AndroidManifest.xml file for Android applications.
/*
* Copyright 2025 Ralf Wondratschek
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import com.android.build.api.artifact.SingleArtifact
import com.android.build.api.variant.AndroidComponentsExtension
import org.gradle.api.DefaultTask
import org.gradle.api.GradleException
import org.gradle.api.Project
import org.gradle.api.file.DirectoryProperty
import org.gradle.api.file.RegularFile
import org.gradle.api.file.RegularFileProperty
import org.gradle.api.provider.Property
import org.gradle.api.tasks.CacheableTask
import org.gradle.api.tasks.Copy
import org.gradle.api.tasks.Input
import org.gradle.api.tasks.InputFile
import org.gradle.api.tasks.OutputDirectory
import org.gradle.api.tasks.OutputFile
import org.gradle.api.tasks.PathSensitive
import org.gradle.api.tasks.PathSensitivity
import org.gradle.api.tasks.TaskAction
import org.gradle.language.base.plugins.LifecycleBasePlugin
import org.gradle.process.ExecOperations
import java.io.ByteArrayOutputStream
import javax.inject.Inject
@CacheableTask
abstract class GenerateAndroidManifestBaselineTask : DefaultTask() {
@get:OutputFile
abstract val generatedManifest: RegularFileProperty
@get:PathSensitive(PathSensitivity.NONE)
@get:InputFile
abstract val mergedManifest: RegularFileProperty
@TaskAction
fun taskAction() {
generatedManifest.asFile.get().writeText(mergedManifest.get().readMergedManifest())
}
}
@CacheableTask
abstract class CheckAndroidManifestDiffTask : DefaultTask() {
// In order for the task to be up-to-date when the inputs have not changed,
// the task must declare an output, even if it's not used. Tasks with no
// output are always run regardless of whether the inputs changed
@get:OutputDirectory
abstract val output: DirectoryProperty
@get:PathSensitive(PathSensitivity.NONE)
@get:InputFile
abstract val baselineManifest: RegularFileProperty
@get:PathSensitive(PathSensitivity.NONE)
@get:InputFile
abstract val generatedManifest: RegularFileProperty
@get:Input
abstract val updateManifestTaskName: Property<String>
@get:Inject
abstract val execOperations: ExecOperations
override fun getGroup(): String = LifecycleBasePlugin.VERIFICATION_GROUP
@TaskAction
fun taskAction() {
val baselineContent = baselineManifest.get().asFile.readText().trim()
val generatedContent = generatedManifest.get().asFile.readText().trim()
if (baselineContent != generatedContent) {
val diffOutputStream = ByteArrayOutputStream()
execOperations.exec {
it.commandLine(
"diff",
"-u",
baselineManifest.get().asFile.absolutePath,
generatedManifest.get().asFile.absolutePath,
)
it.isIgnoreExitValue = true
it.standardOutput = diffOutputStream
it.errorOutput = diffOutputStream
}
// drop(4) will skip the file names with their timestamp. That's irrelevant for our purposes and only adds noise.
val diffOutput = diffOutputStream.toString().lines().drop(4).joinToString(separator = "\n")
throw GradleException(
"The merged AndroidManifest.xml is different from the baseline! " +
"If this change is intended, run ./gradlew ${updateManifestTaskName.get()}\n\n" +
"Diff:\n\n$diffOutput\n\n" +
"Baseline:\n\n$baselineContent\n\n" +
"Merged AndroidManifest.xml:\n\n$generatedContent",
)
}
}
}
private fun RegularFile.readMergedManifest(): String {
// Reads the file and transforms the content. For now it replaces the ever changing version code and version name with a constant.
return asFile.readText()
.replace(Regex("""android:versionCode="\d+""""), """android:versionCode="-1"""")
.replace(Regex("""android:versionName="[^"]*""""), """android:versionName="1.0"""")
}
private fun String.capitalized(): String = replaceFirstChar { if (it.isLowerCase()) it.titlecase() else it.toString() }
fun Project.configureAndroidManifestBaselineTasks() {
extensions.getByType(AndroidComponentsExtension::class.java).onVariants { variant ->
val capitalizedVariantName = variant.name.capitalized()
val generateBaselineTaskName = "generateAndroidManifestBaseline${capitalizedVariantName}"
val updateBaselineTaskName = "updateAndroidManifestBaseline${capitalizedVariantName}"
val checkBaselineTaskName = "checkAndroidManifestBaseline${capitalizedVariantName}"
val generatedFile = layout.buildDirectory.file("intermediates/$generateBaselineTaskName/AndroidManifestBaseline.xml")
val baselineFile = layout.projectDirectory.file("manifest-baseline/${variant.name}/AndroidManifestBaseline.xml")
val mergedManifest = variant.artifacts.get(SingleArtifact.MERGED_MANIFEST)
val generateTask = tasks.register(generateBaselineTaskName, GenerateAndroidManifestBaselineTask::class.java) {
it.mergedManifest.set(mergedManifest)
it.generatedManifest.set(generatedFile)
}
tasks.register(updateBaselineTaskName, Copy::class.java) {
it.from(generateTask.map(GenerateAndroidManifestBaselineTask::generatedManifest))
it.into(baselineFile.asFile.parentFile)
}
tasks.register(checkBaselineTaskName, CheckAndroidManifestDiffTask::class.java) {
it.generatedManifest.set(generateTask.flatMap(GenerateAndroidManifestBaselineTask::generatedManifest))
it.baselineManifest.set(baselineFile)
it.updateManifestTaskName.set(generateBaselineTaskName)
it.output.set(project.layout.buildDirectory.dir("intermediates/$checkBaselineTaskName"))
}
}
}
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