code: func (s *Server) ContainerStats(ctx context.Context, req *pb.ContainerStatsRequest) (resp *pb.ContainerStatsResponse, err error) {
  	const operation = "container_stats"
  	defer func() {
  		recordOperation(operation, time.Now())
  		recordError(operation, err)
  	}()
  
  	container := s.GetContainer(req.ContainerId)
  	if container == nil {
  		return nil, fmt.Errorf("invalid container")
  	}
  
  	stats, err := s.Runtime().ContainerStats(container)
  	if err != nil {
  		return nil, err
  	}
  
  	return &pb.ContainerStatsResponse{Stats: buildContainerStats(stats, container)}, nil
  }
docs: // ContainerStats returns stats of the container. If the container does not
  // exist, the call returns an error.