responses.md

Responses

When a controller action returns NULL, SwaggerBundle will return an empty 204 response, provided that one is defined in the specification. Otherwise, it will default to the first 2xx type response defined in your spec, or if all else fails, simply 200.

You cannot return Symfony responses from your controllers. Any response manipulation (including custom status codes) you want needs to be implemented using "Response Listeners". Example that sets some headers:

services:
  your_response_listener:
    class: Some\Namespace\ResponseListener
    tags:
      - { name: kernel.event_listener, event: kernel.response, method: onKernelResponse }

class ResponseListener
{
    /**
     * @param FilterResponseEvent $event
     */
    public function onKernelResponse(FilterResponseEvent $event)
    {
        if (!$event->isMasterRequest()) {
            return;
        }
        $request = $event->getRequest();
        $headers = $event->getResponse()->headers;
        switch ($request->attributes->get('_swagger_path')) {
            case '/user/login':
                $headers->set('X-Rate-Limit', 123456789);
                $headers->set('X-Expires-After', date('Y-m-d\TH:i:s\Z'));
                break;
            default:
                //noop
        }
    }
}