We had an onslaught of critical failures from Nagios reporting disk space issues on node2.

workbench-node2/Disk is CRITICAL:

DISK CRITICAL - free space: /media/host/var/lib/docker/overlay/78122a97e0772a0f1e7948ca43760a84c32c7710a64c459196354a3c737824c4/merged/dev/termination-log 0 MB (0% inode=-)]: 

The nrpe check_disk command looks at /dev/vdx, but the error is reporting a docker overlay subdirectory. After further investigation, it looks like we'd be better off with check_disk using /media/host, which is where the host root volume is mounted in the NRPE container.