Example of accepting a file via post

SimpleFileUpload.scala

import java.io.File

import akka.actor.ActorSystem
import akka.http.scaladsl.Http
import akka.http.scaladsl.server.Directives._

import akka.stream.ActorMaterializer
import akka.stream.scaladsl.{Sink, Source}

import scala.io.StdIn

object SimpleFileUpload {

  def main(args: Array[String]): Unit = {
    implicit val system = ActorSystem("my-system")
    implicit val materializer = ActorMaterializer()
    import system.dispatcher

    val route =
      path("upload") {
        post {
          extractRequest { request =>
            val file = File.createTempFile("tmp", "dat")
            val futureDone = request.entity.dataBytes
              .runWith(Sink.file(file))

            onComplete(futureDone) { _ =>
              complete("ok: " + file.getAbsolutePath)
            }
          }
        }
      }

    val bindingFuture = Http().bindAndHandle(route, "localhost", 8080)

    println(s"Server online at http://localhost:8080/\nPress RETURN to stop...")
    StdIn.readLine()

    import system.dispatcher
    // for the future transformations
    bindingFuture
      .flatMap(_.unbind()) // trigger unbinding from the port
      .onComplete(_ ⇒ system.shutdown()) // and shutdown when done
  }
}