Importing a instance from RBD backend

There needs to be ability, while moving between clouds, to import a instance into nova database, from X rbd pool, if RBD pool cloud can connect to.
Right now -

I am able to cp or snap/clone between two rbd pools, and or by doing "rbd mv src target" (within same pool). I keep cinder volume as placeholder by deleting rbd volume under that, and then with above method populate cinder volume back. And make it bootable.

Whereas I see, all this should be possible through API or CLI calls ..