Kubernetes: using OpenStack Cinder from one cloud provider while nodes on another
There seem to be new ways to attach Cinder storage to bare metal, but it's apparently just PoC
http://blog.e0ne.info/post/Attach-Cinder-Volume-to-the-Ironic-Instance-without-Nova.aspx
Unfortunately, I don't think you can decouple the cloud provider for the node and that for the volume, at least not in the vanilla kubernetes.