// processChange takes the backend change notification emitted by the backend and applies it to the server func processChange(p proxy.Proxy, ch interface{}) error { switch change := ch.(type) { case *engine.HostUpserted: return p.UpsertHost(change.Host) case *engine.HostDeleted: return p.DeleteHost(change.HostKey) case *engine.ListenerUpserted: return p.UpsertListener(change.Listener) case *engine.ListenerDeleted: return p.DeleteListener(change.ListenerKey) case *engine.FrontendUpserted: return p.UpsertFrontend(change.Frontend) case *engine.FrontendDeleted: return p.DeleteFrontend(change.FrontendKey) case *engine.MiddlewareUpserted: return p.UpsertMiddleware(change.FrontendKey, change.Middleware) case *engine.MiddlewareDeleted: return p.DeleteMiddleware(change.MiddlewareKey) case *engine.BackendUpserted: return p.UpsertBackend(change.Backend) case *engine.BackendDeleted: return p.DeleteBackend(change.BackendKey) case *engine.ServerUpserted: return p.UpsertServer(change.BackendKey, change.Server) case *engine.ServerDeleted: return p.DeleteServer(change.ServerKey) } return fmt.Errorf("unsupported change: %#v", ch) }