Kubelet_volume_stats not in prometheus stats

We also want to monitor the usage of our PVs and are missing the metrics (e.g. kubelet_volume_stats_available_bytes) in Prometheus.

I think the metrics has to be implemented by Longhorn, or not? Should this already work and we are missing a configurations in prometheus?

Has anybody a working solution for monitoring the size and usage of PVs? Thx.