Play Framework Remote Configuration

MyAppLoader.scala

package your.package

import scala.concurrent.duration._

import play.api.{ApplicationLoader, Configuration}
import play.api.inject.guice.{GuiceApplicationBuilder, GuiceApplicationLoader}

import scala.concurrent.{Await, Future}

class MyAppLoader extends GuiceApplicationLoader() {
  override def builder(context: ApplicationLoader.Context): GuiceApplicationBuilder = {
    
    // we're forced to use this form of Configuration because internally, Play requires
    // an instance that implements [[MergeableValue]] which is not available to us for
    // building our own implementations.  
    // TODO: move the data mapping somewhere else
    val extra = Configuration("remote.welcomeMessage" -> remoteConfig.fetchWelcomeMessage())
    initialBuilder
      .in(context.environment)
      .loadConfig(extra ++ context.initialConfiguration)
      .overrides(overrides(context): _*)
  }

}

object remoteConfig {

  /**
    * Retrieve the welcome message from a network resource, etc
    * @return
    */
  def fetchWelcomeMessage(): String = {
    import scala.concurrent.ExecutionContext.Implicits.global
    
    // pointless use of a future with an await to simulate what an actual call to an async
    // resource would look like; have to await here because there's no way to asynchronously
    // supply configuration values to the Configuration instance above.
    Await.result(Future {
      "I came from space!!!"
    }, 10.seconds)
  }
}

You also need to configure this as the app's new application loader in your application.conf:

play.application.loader = "your.package.MyAppLoader"

Now, you can use remote params like any other in your app:

Logger.info(configuration.get[String]("remote.welcomeMessage"))