Booting Akka with Cats Effect

Server2.scala

import akka.actor.ActorSystem
import akka.http.scaladsl.Http
import akka.http.scaladsl.server.Directives._
import cats.effect.{IO, IOApp, Resource}
import cats.syntax.all.catsSyntaxMonadErrorRethrow
import ch.megard.akka.http.cors.scaladsl.CorsDirectives.cors
import com.google.cloud.texttospeech.v1.TextToSpeechClient
import com.typesafe.scalalogging.LazyLogging

object Boot extends IOApp.Simple with LazyLogging {
  def logInfo(message: String): IO[Unit] = IO(logger.info(message)).void

  def mkTextToSpeechClient(): Resource[IO, TextToSpeechClient] =
    Resource.make(IO(TextToSpeechClient.create()))(client => IO(client.shutdown()))
      .evalTap(_ => logInfo("TextToSpeech Client Started"))
      .onFinalize(logInfo("TextToSpeech Client Finalized"))

  def mkServer(config: Configuration,
               ttsClient: TextToSpeechClient)
              (implicit actorSystem: ActorSystem): Resource[IO, Http.ServerBinding] =
    Resource.make {
      IO.fromFuture(IO(
        Http()(actorSystem)
          .newServerAt(config.voice.interface, config.voice.port)
          .bindFlow(cors()(get(complete(s"Voice ${BuildInfo}"))))
      ))
    }(binding => IO.fromFuture(IO(binding.unbind())).void)

  def mkActorSystem(): Resource[IO, ActorSystem] =
    Resource.make(IO(ActorSystem("voice-backend")))(
      system => IO.fromFuture(IO(system.terminate())).void)

  def printBanner(): IO[Unit] =
    logInfo(s"""Voice $BuildInfo""".stripMargin)

  val run: IO[Unit] =
    (for {
      _ <- Resource.eval(printBanner())
      config <- Resource.eval(IO(Configuration.load()).rethrow)
      client <- mkTextToSpeechClient()
      system <- mkActorSystem()
      server <- mkServer(config, client)(system)
    } yield {
      server
    }).use(_ => IO.never)
}