Description of problem:

when unshelving an instance of the shelve-offload state, it can't assign an instance to specific host

When unshelving an instance, is it possible to select a specific host using the Availability Zone, just like when creating an instance using availability zones to select hosts?

(overcloud_test) [stack@undercloud ~]$ openstack help server unshelve
usage: openstack server unshelve [-h] [--availability-zone AVAILABILITY_ZONE]
<server> [<server> ...]

Unshelve server(s)

positional arguments:
<server> Server(s) to unshelve (name or ID)

optional arguments:
-h, --help show this help message and exit
--availability-zone AVAILABILITY_ZONE
Name of the availability zone in which to unshelve a
SHELVED_OFFLOADED server (supported by -os-compute
api-version 2.77 or above)

Version-Release number of selected component (if applicable):

Red Hat OpenStack 16.1

How reproducible:

Always

Steps to Reproduce:
1.
2.
3.

Actual results:

Expected results:
We have successfully unshelved an instance to specific host

Additional info:

when unshelving an instance of the shelve-offload state, it is difficult to manage unshelved an instance if the specific HOST is not assigned because we don't know which host an instance will be assigned to