Starting an Akka HTTP server (akka-http version 10.2.8)

AkkaHttpServer.scala

import scala.concurrent.ExecutionContext
import scala.concurrent.duration.DurationInt
import scala.util.{ Failure, Success }

import akka.Done
import akka.actor.{ ActorSystem, CoordinatedShutdown }
import akka.http.scaladsl.Http
import akka.http.scaladsl.server.Route

object AkkaHttpServer {

  def start(name: String, routes: Route, port: Int)(implicit system: ActorSystem): Unit = {

    implicit val ec: ExecutionContext = system.dispatcher
    val shutdown                      = CoordinatedShutdown(system)

    Http().newServerAt("0.0.0.0", port).bind(routes).onComplete {
      case Success(binding) =>
        val address = binding.localAddress
        val uri     = s"http://${address.getHostString}:${address.getPort}"

        system.log.info("{} online at {}", name, uri)

        shutdown.addTask(CoordinatedShutdown.PhaseServiceRequestsDone, "http-graceful-terminate") { () =>
          binding.terminate(10.seconds).map { _ =>
            system.log.info("{} at {} graceful shutdown completed", name, uri)
            Done
          }
        }
      case Failure(ex) =>
        system.log.error("Failed to bind HTTP endpoint, terminating system", ex)
        system.terminate()
    }
  }
}

HttpRoutes.scala

import akka.http.scaladsl.model.{ ContentTypes, HttpEntity }
import akka.http.scaladsl.server.Directives._
import akka.http.scaladsl.server.Route

object HttpRoutes {

  lazy val all: Route = concat(helloRoute, greetRoute)

  private lazy val helloRoute =
    path("hello") {
      get {
        complete(HttpEntity(ContentTypes.`text/html(UTF-8)`, "<h1>Say hello to akka-http</h1>"))
      }
    }

  private lazy val greetRoute =
    path("hello" / Segment) { name =>
      get {
        complete(s"Hello, $name")
      }
    }
}

Main.scala

import akka.actor.ActorSystem

object Main {

  def main(args: Array[String]): Unit = {
    implicit val system: ActorSystem = ActorSystem("main-system")

    // Start http server on port 8080
    AkkaHttpServer.start("api-server", HttpRoutes.all, 8080)
  }
}