Error building Android library: Direct local .aar file dependencies are not supported on multi module app

Question

I have a multi module app and I want to implement a aar file on a secondary module. I app module works fine if I implement the aar but I need on my secondary module.

But I'm receiving this error:

Direct local .aar file dependencies are not supported when building an AAR. The resulting AAR would be broken because the classes and Android resources from any local .aar file dependencies would not be packaged in the resulting AAR. Previous versions of the Android Gradle Plugin produce broken AARs in this case too (despite not throwing this error). The following direct local .aar file dependencies of the :features:second-module project caused this error: D:\user\my-app\features\second-module\libs\sdk-v3.0.1.aar

I'm adding libs on flatDir:

repositories {
  flatDir {
     dirs 'libs'
  }
}

And this is how I implementing the SDK:

    implementation fileTree(include: ['sdk-v3.0.1.aar'], dir: 'libs' )

Answer 1

Following Andrei Kuznetsov's advice, we use an embedded maven repo wherever an inattentive vendor provide us an AAR file. While it seems complicated at first, it requires just a few command line instructions and add a couple of xml files to the project.

On macOS it is just a matter of:

1. Installing mvn via Homebrew

    brew install maven      
   

2. Creating a directory for the embedded local repository

    cd YOUR_PROJECT_ROOT
    mkdir repo
   

3. Installing the aar in the repo with a reasonable group ID, artifact ID and version (e.g. com.groupid:artifactid:1.0.0)

    mvn install:install-file -Dfile=<SOURCE_AAR_PATH> -DgroupId=com.groupid -DartifactId=artifactid -Dversion=1.0.0 -Dpackaging=aar -DlocalRepositoryPath=<YOUR_PROJECT_DIR>/repo
   

4. Add the repository to the project

    // Project's build.gradle
    allProjects {
        repositories {
            ... // Other repos
            maven { url "file://${rootDir}/repo" }
        }
    }
   

5. Declare the dependency as usual

    // Module's build.gradle
    dependencies {
        ... // Other deps
        implementation("com.groupid:artifactid:1.0.0")
    }
   

That's it.

Just remember to also declare the AAR dependencies it the POM file

    <!-- repo/com/groupid/artifactid/1.0.0/artifactid-1.0.0/pom -->
    <project>
      <groupId>com.groupid</groupId>
      <artifactId>artifactid</artifactId>
      <version>1.0.0</version>
      <dependencies>
        <!-- here -->
      </dependencies>
    </project>

Answer 2

This seems to be a dependency transfer problem.

Currently, your second module has a dependency on the aar by the way of "implementation", and your app module has a dependency on your secend module. Therefore, your app module can't access to the aar.

To fix that, you can let your second module depend on the aar by the way of "api", by which, any module depending on the secend module can access to the aar.

api fileTree(include: ['sdk-behavior-v3.0.1-release.aar'], dir: 'libs' )

Answer 3

Change this:

implementation fileTree(include: ['sdk-v3.0.1.aar'], dir: 'libs' )

to this:

compileOnly fileTree(include: ['sdk-v3.0.1.aar'], dir: 'libs' )