code: func (daemon *Daemon) containerPause(container *container.Container) error {
  	container.Lock()
  	defer container.Unlock()
  
  	// We cannot Pause the container which is not running
  	if !container.Running {
  		return errNotRunning(container.ID)
  	}
  
  	// We cannot Pause the container which is already paused
  	if container.Paused {
  		return errNotPaused(container.ID)
  	}
  
  	// We cannot Pause the container which is restarting
  	if container.Restarting {
  		return errContainerIsRestarting(container.ID)
  	}
  
  	if err := daemon.containerd.Pause(context.Background(), container.ID); err != nil {
  		return fmt.Errorf("Cannot pause container %s: %s", container.ID, err)
  	}
  
  	container.Paused = true
  	daemon.setStateCounter(container)
  	daemon.updateHealthMonitor(container)
  	daemon.LogContainerEvent(container, "pause")
  
  	if err := container.CheckpointTo(daemon.containersReplica); err != nil {
  		logrus.WithError(err).Warn("could not save container to disk")
  	}
  
  	return nil
  }
docs: // containerPause pauses the container execution without stopping the process.
  // The execution can be resumed by calling containerUnpause.