Task for publishing in Fabric (with build number increment)

fabric_gradle_task.gradle

...

android {
  def versionPropsFile = file('version.properties')
  def Properties versionProps = new Properties()
  versionProps.load(new FileInputStream(versionPropsFile))
  def buildNumber = versionProps['VERSION_BUILD'].toInteger() + 1
  
  defaultConfig {
    versionCode buildNumber
    ...
  }
}

....

android.applicationVariants.all { variant ->
    task("beta${variant.name.capitalize()}")
            .dependsOn(
                "assemble${variant.name.capitalize()}",
                "crashlyticsUploadDistribution${variant.name.capitalize()}",
                "increaseVersionCode${variant.name.capitalize()}")

    task("increaseVersionCode${variant.name.capitalize()}") << {
        def versionPropsFile = file('version.properties')
        def Properties versionProps = new Properties()
        versionProps.load(new FileInputStream(versionPropsFile))
        def newCode = versionProps["${versionPropsName}"].toInteger() + 1
        versionProps['VERSION_BUILD'] = newCode.toString()
        versionProps.store(versionPropsFile.newWriter(), null)

        println sprintf(" >>> " + variant.name.capitalize() + " version code incremented: %d", newCode)
    }
}