Example for building android library module (in project) with custom variant

build.gradle

//snippet from library module
android {
    defaultPublishConfig "productionRelease"
    publishNonDefault true

    productFlavors {
        alpha {
        }
        production {
        }
    }
}

//snippet from android application module
dependencies {
    compile project(path: ':module', configuration:'alphaDebug')
}