Rancher monitoring app shows not all mounted node filesystems

We use the Rancher Monitoring App (from Cluster Explorer) for our cluster and have troubles with monitoring the host filesystem. On the nodes we have the following mount points:

/var  <-- lv_var
/var/log  <-- lv_var_log 
/var/lib  <-- lv_var_lib 
/var/lib/docker  <-- lv_var_lib_docker 

but in Prometheus we see only the the /var mount point.

node_filesystem_avail_bytes{device="/dev/mapper/rootvg-var_lv",endpoint="metrics",fstype="ext4",instance="10.238.22.214:9796",job="node-exporter",mountpoint="/var",namespace="cattle-monitoring-system",node="worker101",pod="rancher-monitoring-prometheus-node-exporter-hl8fr",service="rancher-monitoring-prometheus-node-exporter"}

Is there an additionally config which we must provide when we want monitor not only the root mount points?

Regards