How to get the remaining cull time for the running container

We set the cull idle time with "--MappingKernelManager.cull_idle_timeout=64800 " in the customized container image and want to show to our user the remaining time the container will be shutdown. We put a timer that calculate the time from container system running time but I believe it is not fully synchronous with the remaining cull time.

Is there any API to call to get the remaining time before the kernel is closed?