rook: kubelet_volume* / persistent volume metrics missing

Is this a bug report or feature request? BUG

• Bug Report

Bug Report /kind bug

What happened: I am trying to get kubelet_volume_* metrics working. According this google/cadvisor#1702 (comment) there should be support after 1.8 kube. However, I am now using kube 1.10.0 and still cannot see anything in /metrics? Should these be there or not?

curl -s https://localhost:10255/metrics -k|grep kubelet_volume|wc -L
0

pvc-d64b963b-4578-11e8-9cf2-d4ae526fcc30   100Gi      RWO            Delete           Bound     default/prom-test-prometheus-server         rook-block               2d

prom-test-prometheus-server         Bound     pvc-d64b963b-4578-11e8-9cf2-d4ae526fcc30   100Gi      RWO            rook-block     2d

What you expected to happen: I except that kubelet should expose prometheus volume metrics to /metrics path as well. Then it is easy to read with prometheus and to monitor the persistent volume usage status How to reproduce it (minimal and precise):

Create the default storage-class and a persistent-volume-claim but no persistent volume metrics will be published

Environment:

• OS (e.g. from /etc/os-release): Debian GNU/Linux 9.4
• Kernel (e.g. uname -a): 4.9.0-6-amd64
• Cloud provider or hardware configuration: Bare-Metal
• Rook version (use rook version inside of a Rook Pod): v0.7.0-87.g2d40c08
• Kubernetes version (use kubectl version):

Client Version: version.Info{Major:"1", Minor:"10", GitVersion:"v1.10.1", GitCommit:"d4ab47518836c750f9949b9e0d387f20fb92260b", GitTreeState:"clean", BuildDate:"2018-04-12T14:26:04Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"10", GitVersion:"v1.10.0", GitCommit:"fc32d2f3698e36b93322a3465f63a14e9f0eaead", GitTreeState:"clean", BuildDate:"2018-03-26T16:44:10Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"linux/amd64"}

• Kubernetes cluster type (e.g. Tectonic, GKE, OpenShift): Bare-metal
• Ceph status (use ceph health in the Rook toolbox):

root@rook-tools:/# ceph -s
  cluster:
    id:     6af9b6be-2998-4b56-8d62-37fa609f5bde
    health: HEALTH_OK
 
  services:
    mon: 3 daemons, quorum rook-ceph-mon0,rook-ceph-mon2,rook-ceph-mon1
    mgr: rook-ceph-mgr0(active)
    osd: 9 osds: 9 up, 9 in
 
  data:
    pools:   2 pools, 200 pgs
    objects: 3040 objects, 10636 MB
    usage:   220 GB used, 16541 GB / 16762 GB avail
    pgs:     200 active+clean
 
  io:
    client:   42977 B/s wr, 0 op/s rd, 1 op/s wr

Please have a look at this issue currently it is not possible to monitor the pv usage. tia