CorsSupport.scala

import spray.http.HttpMethods._
import spray.http.{HttpResponse, HttpMethod, HttpMethods, AllOrigins}
import spray.http.HttpHeaders.{`Access-Control-Allow-Methods`, `Access-Control-Max-Age`, `Access-Control-Allow-Headers`, `Access-Control-Allow-Origin`}
import spray.routing._
import spray.routing.directives.BasicDirectives

/**
 * Forked from
 *
 * https://gist.github.com/joseraya/176821d856b43b1cfe19
 *
 * See Also
 * https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS
 * http://www.html5rocks.com/en/tutorials/cors/#toc-adding-cors-support-to-the-server
 */
trait CORSSupport extends BasicDirectives{

  private val allowOriginHeader = `Access-Control-Allow-Origin`(AllOrigins)
  private val optionsCorsHeaders = List(
    `Access-Control-Allow-Headers`("Origin, X-Requested-With, Content-Type, Accept, Accept-Encoding, Accept-Language, Host, Referer, User-Agent"),
    `Access-Control-Max-Age`(1728000))

  def cors[T]: Directive0 = mapRequestContext { ctx => ctx.withRouteResponseHandling({
    //It is an option requeset for a resource that responds to some other method
    case Rejected(x) if ctx.request.method.equals(HttpMethods.OPTIONS) && !x.filter(_.isInstanceOf[MethodRejection]).isEmpty =>
      val allowedMethods: List[HttpMethod] = x.filter(_.isInstanceOf[MethodRejection]).map(rejection => {
        rejection.asInstanceOf[MethodRejection].supported
      })

      ctx.complete(HttpResponse().withHeaders(
        `Access-Control-Allow-Methods`(OPTIONS, allowedMethods: _*) :: allowOriginHeader ::
          optionsCorsHeaders
      ))
  }).withHttpResponseHeadersMapped { headers =>
    allowOriginHeader :: headers

  }
  }
}

Example.txt

val routes: Route =
  cors {
    path("hello") {
      get {
        complete {
          "GET"
        }
      } ~
      put {
        complete {
          "PUT"
        }
      }
    }
  }