UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36

Steps to reproduce the problem:
Using Google Container Engine, on Kubernetes 1.6.2, I am not able to map Ceph volumes because the Kernel module `RBD` from the COS image is not present.

To reproduce, create a Kubernetes cluster using GKE and COS image. SSH into one of the node and execute `modprobe rbd`

What is the expected behavior?
RBD Kernel Module to be available so that Ceph volumes can be mounted on Kubernetes Applications on GKE using COS image.

What went wrong?
RBD Kernel Module is not present. This is what i see when doing `modprobe rbd`

# modprobe rbd
modprobe: FATAL: Module rbd not found in directory /lib/modules/4.4.35+

Did this work before? No 

Chrome version:   Channel: stable
OS Version: 
Flash Version: 

I am deploying Rook (https://github.com/rook/rook). Rook is a platform that provides software defined storage based on Ceph and natively integrates to Kubernetes. The deployment goes well but when the time comes to mount RBD volumes to the host, it fails because RBD kernel modules is not available in COS images.

The fix normally consists in using `modprobe rbd` to each Kubernetes node, But it won't work on the COS image type.

I was told in the Kubernetes community to submit a bug here. If this is not the right place, I apologize, and hopefully you could guide me to where i should post this issue. Thank you very much.