code: func RunGRPCServer() error {
  	if !gorush.PushConf.GRPC.Enabled {
  		gorush.LogAccess.Debug("gRPC server is disabled.")
  		return nil
  	}
  
  	lis, err := net.Listen("tcp", ":"+gorush.PushConf.GRPC.Port)
  	if err != nil {
  		gorush.LogError.Errorf("failed to listen: %v", err)
  		return err
  	}
  	s := grpc.NewServer()
  	srv := NewServer()
  	proto.RegisterGorushServer(s, srv)
  	proto.RegisterHealthServer(s, srv)
  	// Register reflection service on gRPC server.
  	reflection.Register(s)
  	gorush.LogAccess.Debug("gRPC server is running on " + gorush.PushConf.GRPC.Port + " port.")
  	if err := s.Serve(lis); err != nil {
  		gorush.LogError.Errorf("failed to serve: %v", err)
  		return err
  	}
  
  	return nil
  }
docs: // RunGRPCServer run gorush grpc server