CORS issue / akka-http-cors / No ‘Access-Control-Allow-Origin’ header is present on the requested resource in Scala/Java

How do I implement akka-http-cors correctly to be able to allow access from any origin (domain, in my case localhost:3000) to a Https Server (Scala/Akka)?

Based on the akka-http-cors documentation should defaultSettings do the job, but I am still doing something wrong:

  ...

  import ch.megard.akka.http.cors.scaladsl.CorsDirectives._

  var settings = CorsSettings.defaultSettings 
    
  lazy val theRequestRoutes: Route =
    cors(settings) {
      pathPrefix("getsearchresult") {
        post { 
          entity(as[Server.ReqGetSearchResult]) { request: ReqGetSearchResult =>
            val operationPerformed: Future[Server.ServerResponse] = controller.ask(ControllerActor.Request_GetSearchResult(_, request))
            onSuccess(operationPerformed) {
              case Server.Send_Response_Success(jsonResponse) => complete(jsonResponse)
              case Server.Send_Response_Failure(status) => complete("""{"status":"server_error"}""")
            }
          }
        }
      }
    }
  ...

val https: HttpsConnectionContext = getHttpsConnectionContext()
val serverBinding: Future[Http.ServerBinding] = Http().newServerAt(host, port).enableHttps(https).bind(theRequestRoutes)

---

libraryDependencies += "ch.megard" %% "akka-http-cors" % "1.1.2"

---

Google Chrome Error:

Access to XMLHttpRequest at 'https://api.domain.com:8080/getsearchresult' from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

Firefox Error:

Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://api.domain.com:8080/getsearchresult. (Reason: CORS header ‘Access-Control-Allow-Origin’ missing).

---

akka-http-core: https://github.com/lomigmegard/akka-http-cors#configuration

Any help is highly appreciated!

Answer

The problem in my case was that I haven’t done Marshalling in the right way, thereby it crashed in following line:

entity(as[Server.ReqGetSearchResult]) { request: ReqGetSearchResult =>

Surprisingly to me, that the error is than labeled as CORS error.

I solved it by checking the Akka HTTP JSON Support manual: https://doc.akka.io/docs/akka-http/current/common/json-support.html

It now works for me in my case by having this upfront:

trait JsonSupport extends SprayJsonSupport with DefaultJsonProtocol {
   implicit val clientRequestFormat = jsonFormat5(Server.ReqGetSearchResult)
}

class RequestRoutes(controller: ActorRef[Controller.Command])(implicit system: ActorSystem[_]) extends Directives with JsonSupport {
   import akka.actor.typed.scaladsl.AskPattern.schedulerFromActorSystem
   import akka.actor.typed.scaladsl.AskPattern.Askable
   implicit val timeout: Timeout = 60.seconds

   ... (code from above)
}