Comment 8 for bug 1811235

Resize does not allow specifying a target host at all. Specifying a target host only applies (in that code) for cold migrate:

https://developer.openstack.org/api-ref/compute/#resize-server-resize-action

https://developer.openstack.org/api-ref/compute/#migrate-server-migrate-action

The host parameter was added in the 2.56 microversion.

The allow_resize_to_same_host option really only makes sense for resize when the flavor changes. For cold migrate the flavor does not change, so what is the point of cold migrating a server to the same host?

As noted earlier, the cold migration might just fail in that case anyway if the virt driver doesn't support it:

https://github.com/openstack/nova/blob/9419c3e05499e55beda93d664197a7b0f0011ff7/nova/compute/manager.py#L4172

It looks like the only driver that does support cold migrate to the same host is the vcenter driver (because that is a cluster driver where the single nova-compute manages a single vcenter cluster which could have hundreds of ESXi hosts on it).

Are you using the vcenter driver in your deployment?