Comment 1 for bug 1675276

This is mostly working as designed.

When attaching a volume to a shelved offloaded instance, there is no host for the instance so we can't call to the compute manager to reserve the device like we do for a normal attach here:

http://git.openstack.org/cgit/openstack/nova/tree/nova/compute/api.py#n3687

So we create the BDM in the API and don't set a device name, because we can't say it's going to be the device name when we unshelve the instance:

http://git.openstack.org/cgit/openstack/nova/tree/nova/compute/api.py#n3678

We've long talked about just removing the device_name option from the volume attach API because we can't guarantee that what the user requests is what's going to be in the guest, the hypervisor controls that, not nova. The libvirt driver completely ignores the user-requested device name.

So I think we want a spec to microversion the device_name field out of the volume attach request since it's just confusing and we can't honor it.

The thing we need to check is it the os-attach API in Cinder requires the mountpoint (which is the device name in the nova BDM).