Docker not forwarding http requests - scala

Question

I am running a Scala microservice application in my local docker container and trying to test it manually by using Postman but I am constantly getting a socket error:
Error: socket hang up
My application listens to 8080 port as main function contains:
val bindingFuture = Http()
.newServerAt("localhost", 8080)
.bind(userRoute.route)
I am running my container by forwarding 8080 to 8080:
docker run -i -t -d -p 8080:8080 app-core:0.1.0-SNAPSHOT
In container logs I see my application is up and running. Also, when I check with netstat, I see Docker is indeed listening to the 8080 port:
netstat -na | Select-String "8080"
TCP 0.0.0.0:8080 0.0.0.0:0 LISTENING
TCP 127.0.0.1:8080 127.0.0.1:59087 TIME_WAIT
TCP 127.0.0.1:8080 127.0.0.1:59088 TIME_WAIT
TCP [::]:8080 [::]:0 LISTENING
TCP [::1]:8080 [::]:0 LISTENING
But for some reason, my http request is not being forwarded to the application. Any ideas?
Postman ss:
Main.scala:
object Main extends App {
implicit val system = ActorSystem(Behaviors.empty, "hb-core-service-system")
implicit val executionContext = system.executionContext
val db = Database.forConfig("mydb")
val userCommand: UserCommand = new UserCommand(db)
val userRoute = new UserRoute(userCommand)
val bindingFuture = Http()
.newServerAt("127.0.0.1", 8080)
.bind(userRoute.route)
println(
s"Server now online.\nPress RETURN to stop..."
)
StdIn.readLine() // let it run until user presses return
bindingFuture
.flatMap(_.unbind()) // trigger unbinding from the port
.onComplete(_ => system.terminate()) // and shutdown when done
}
UserRoute.scala:
class UserRoute(
user: UserCommand
)(implicit ec: ExecutionContext)
extends JsonFormats {
def route: Route =
pathPrefix("api" / "core-service") {
Directives.concat(
(path("create-user") & post)(createUser)
}
private def createUser: Route =
entity(Directives.as[UserDto]) { dto =>
complete {
user.createUser(dto).map {
case Some(id) =>
id.asJson
case None =>
StatusCodes.BadRequest
}
}
}
}

Answer 1

After hours of research I've realized the problem is basically with the following binding:
val bindingFuture = Http()
.newServerAt("localhost", 8080)
.bind(userRoute.route)
It works perfectly until you put the application inside a docker container. When I changed "localhost" with "0.0.0.0", it started working as expected.