TL'DR: In this Android Kotlin library I updated from Gradle 5.6.4 to 6.6.1 (commit d5d8d2
). Now I cannot build a project depending on the aar anymore.
I build and deploy the aar to mavenLocal ...
$ ./gradlew clean :roadsigns:assemble
$ ./gradlew publishToMavenLocal
... and then reference the deployed library artifact in the sample Android app
module. First I add mavenLocal()
in the root build.gradle file:
allprojects {
repositories {
google()
mavenCentral()
jcenter()
mavenLocal() // <-- Add this
}
}
I reference the mavenLocal()
dependency directly:
dependencies {
implementation
// implementation project(":roadsigns")
implementation "info.metadude.kotlin.library.roadsigns:roadsigns:$version"
implementation Libs.kotlinStdlib
// ...
When I build the sample app then I get the following build error:
$ ./gradlew clean assembleDebug
Execution failed for task ':checkDebugAarMetadata'.
> Multiple task action failures occurred:
> A failure occurred while executing com.android.build.gradle.internal.tasks.CheckAarMetadataWorkAction
> A dependency's AAR metadata (META-INF/com/android/build/gradle/aar-metadata.properties) does
not specify an aarFormatVersion value, which is a required value.
Dependency: info.metadude.kotlin.library.roadsigns:roadsigns:4.0.0.
AAR metadata file: /home/USERNAME/.m2/repository/info/metadude/kotlin/library/roadsigns/roadsigns/4.0.0/roadsigns-4.0.0-javadoc.jar.
> A failure occurred while executing com.android.build.gradle.internal.tasks.CheckAarMetadataWorkAction
> A dependency's AAR metadata (META-INF/com/android/build/gradle/aar-metadata.properties) does
not specify an aarFormatVersion value, which is a required value.
Dependency: info.metadude.kotlin.library.roadsigns:roadsigns:4.0.0.
AAR metadata file: /home/USERNAME/.m2/repository/info/metadude/kotlin/library/roadsigns/roadsigns/4.0.0/roadsigns-4.0.0-sources.jar.
> A failure occurred while executing com.android.build.gradle.internal.tasks.CheckAarMetadataWorkAction
> A dependency's AAR metadata (META-INF/com/android/build/gradle/aar-metadata.properties) does
not specify an aarFormatVersion value, which is a required value.
Dependency: info.metadude.kotlin.library.roadsigns:roadsigns:4.0.0.
AAR metadata file: /home/USERNAME/.m2/repository/info/metadude/kotlin/library/roadsigns/roadsigns/4.0.0/roadsigns-4.0.0.aar.
When I try the same with Gradle 5.6.4 then there is no error.
In the Android Kotlin library I am using:
I using Java 8 (OpenJDK) on my machine and verified that the same error occurs on a different computer.
What changed from Gradle 5 to Gradle 6 which causes the aar to be broken (?)
I took a look at the files being deployed in mavenLocal()
:
~/.m2/repository/info/metadude/kotlin/library/roadsigns
└── roadsigns
├── 4.0.0
│ ├── roadsigns-4.0.0.aar
│ ├── roadsigns-4.0.0-javadoc.jar
│ ├── roadsigns-4.0.0.module
│ ├── roadsigns-4.0.0.pom
│ └── roadsigns-4.0.0-sources.jar
└── maven-metadata-local.xml
I compared the files deployed with Gradle 5 and Gradle 6. Interestingly, the roadsigns-4.0.0.aar
files are binary equivalent. The pom
file differs, though:
Also there is a roadsigns-4.0.0.module
file only when I deploy with Gradle 6.
When I manually remove the "new" do_not_remove: published-with-gradle-metadata
part from the file deployed with Gradle 6 then the app builds successfully! The question remains ... what's going on here?!
I was running into a lot of these errors:
...
The minCompileSdk (31) specified in a
dependency's AAR metadata (META-INF/com/android/build/gradle/aar-metadata.properties)
is greater than this module's compileSdkVersion (android-30).
Dependency: androidx.lifecycle:lifecycle-livedata-core:2.4.0.
AAR metadata file: C:\Users\CUR_USER\.gradle\caches\transforms-3\4e8a32482e233cfbbc450e03aabed8dd\transformed\lifecycle-livedata-core-2.4.0\META-INF\com\android\build\gradle\aar-metadata.properties.
...
What I did to fix it was
build.gradle
(app)compileSdk
to 31 from 30targetSdk
to 31 from 30The problem very likely comes from the plugins you are using to publish the library (digital.wup:android-maven-publish:3.6.3
) and the quite abandoned bintray Gradle plugin which hasn't been updated to support Gradle metadata.
I bet the .module
file that takes precedence over the content of the pom.xml
files in Gradle 6 consumer projects is improperly populated because of how these two plugins work.
Fortunately, there's now built-in maven-publish
support in the Android Gradle Plugin (so first-party), and it's documented here: https://developer.android.com/studio/build/maven-publish-plugin
With it, you can publish to mavenLocal, bintray, and any other proper maven repo.
You should not have any issues if you use that instead of any third party alternatives.
I have the same problem. I found a temporary solution:
Add the aar
suffix to the error module and make it transitive (or you will lose dependencies) e.g.:
implementation "androidx.lifecycle:lifecycle-extensions:2.2.0"
reports "not specify an aarFormatVersion" error, compilation failed.
change to:
implementation ("androidx.lifecycle:lifecycle-extensions:2.2.0@aar") {
transitive = true
}
compile error disappeared.
AS Louis CAD says, you can use built-in 'maven-publish' to solve this issues.
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