The current state is as documented in the GitHub issues that are referened in this thread
First, we need to extend the jupyterhub-idle-culler as described in these issues:
-
https://github.com/jupyterhub/jupyterhub-idle-culler/issues/8
(this also included a working monkey-patch solution) - https://github.com/jupyterhub/jupyterhub-idle-culler/issues/9
The culler is an isolated service that is unaware of the JupyterHub spawner such as DockerSpawner or KubeSpawner. It does not access the JupyterHub settings. Hence, we need to add that functionality in the spawner because of the volume naming strategy, i.e.:
- https://github.com/jupyterhub/kubespawner/issues/415
- https://github.com/jupyterhub/dockerspawner/issues/384
You are more than welcome to join into the discussions and contribute 
I guess until now mostly general discussions are started but we need somebody to try out some of the mentioned options.