This has been fixed in both controller-manager and kubelet.

New location for flexvolume plugin is - /etc/kubernetes/kubelet-plugins/volume/exec . It is a writable location on RHCOS machines and place where flexvolume plugins should be installer.

controller-manager, kubelet and apiserver already has been updated to use this location.

@Hemant,

Could you please point out which build contains the fix?
Thanks.
Hongkai

0.12 installer should already include fixed components.

Hey Hemant

I am using v0.12 and hitting this BZ

$ ./openshift-install-darwin-amd64 version

./openshift-install-darwin-amd64 v0.12.0


Not sure if i am missing something.

Have you tried installing flexvolume plugin in location I pointed out?

Sorry, don't know how to do that. 

Can you send me some instructions that i can try and share feedback with you ?

Thanks

https://github.com/rook/rook/issues/2612#issuecomment-462936256

Thanks @Hongkai for the feedback. I got the same results with him.
$ oc get clusterversion
NAME      VERSION                             AVAILABLE   PROGRESSING   SINCE   STATUS
version   4.0.0-0.nightly-2019-02-20-194410   True        False         28h     Cluster version is 4.0.0-0.nightly-2019-02-20-194410


$ oc get pods -n rook-ceph-system
NAME                                  READY   STATUS    RESTARTS   AGE
rook-ceph-agent-5zlvz                 1/1     Running   0          9m12s
rook-ceph-agent-642qp                 1/1     Running   0          9m12s
rook-ceph-agent-d9mvk                 1/1     Running   0          9m12s
rook-ceph-agent-g6vf7                 1/1     Running   0          9m12s
rook-ceph-agent-sdjh2                 1/1     Running   0          9m12s
rook-ceph-operator-5dd9cd8dc9-9ghms   1/1     Running   0          10m
rook-discover-56nrl                   1/1     Running   0          9m12s
rook-discover-bbbdk                   1/1     Running   0          9m12s
rook-discover-dhbtj                   1/1     Running   0          9m12s
rook-discover-tj9jd                   1/1     Running   0          9m12s
rook-discover-wkr5v                   1/1     Running   0          9m12s

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2019:0758