nova-scheduler does not use image_metadata when resizing instances

[Akira KAMIO]

Description
===========
We found that nova-scheduler does not use image_metadata when resizing instances.

Steps to reproduce
==================
We have several type of hosts using aggregate.

TypeA:
- aggregate metadata
 - image_host_type=A

TypeB:
- aggregate metadata
 - image_host_type=B

And we set image_metadata to use aggregation host.

$ glance image-show da8a7cfd-f30c-465a-a34d-8ffc8b845f03
+------------------+----------------------------------------------------------------------------------+
| Property | Value |
+------------------+----------------------------------------------------------------------------------+
| checksum | aad97895eef66157e6f28baddcff0851 |
| container_format | bare |
| created_at | 2019-08-06T10:34:41Z |
| disk_format | qcow2 |
| id | da8a7cfd-f30c-465a-a34d-8ffc8b845f03 |
| host_type | A |
~~~

Looks good when creating VM.
But, does not work when resizing VM.

$ nova show 5c56d203-4991-49ad-b956-0da6bf83902e

+--------------------------------------+--------------------------------------------------------------+
| Property | Value |
+--------------------------------------+--------------------------------------------------------------+
| OS-DCF:diskConfig | MANUAL |
| OS-EXT-AZ:availability_zone | AZ_A |
| OS-EXT-SRV-ATTR:host | type-a-7044.xxxxxxxxxxxxxxxxxxxxxxxxxxxxx |
| OS-EXT-SRV-ATTR:hypervisor_hostname | type-a-7044.xxxxxxxxxxxxxxxxxxxxxxxxxxxxx |
| OS-EXT-SRV-ATTR:instance_name | instance-0001b0bd |
| OS-EXT-STS:power_state | 1 |
| OS-EXT-STS:task_state | - |
| OS-EXT-STS:vm_state | active |
| OS-SRV-USG:launched_at | 2019-08-26T00:51:48.000000 |
| OS-SRV-USG:terminated_at | - |
| accessIPv4 | |
| accessIPv6 | |
| config_drive | True |
| created | 2019-08-26T00:51:28Z |
| flavor | m1.small (dfe0448b-6761-4c27-bb04-af1484701d7e) |
| hostId | 163e1b25a943504d14a669e46ed86fd861d63b567c2cc551df9eefcf |
| id | 5c56d203-4991-49ad-b956-0da6bf83902e |
~~~

$ nova resize 5c56d203-4991-49ad-b956-0da6bf83902e m1.medium
$ nova show 5c56d203-4991-49ad-b956-0da6bf83902e
+--------------------------------------+--------------------------------------------------------------+
| Property | Value |
+--------------------------------------+--------------------------------------------------------------+
| OS-DCF:diskConfig | MANUAL |
| OS-EXT-AZ:availability_zone | AZ_A |
| OS-EXT-SRV-ATTR:host | type-b-7002.xxxxxxxxxxxxxxxxxxxxxxxxxxxxx |
| OS-EXT-SRV-ATTR:hypervisor_hostname | type-b-7002.xxxxxxxxxxxxxxxxxxxxxxxxxxxxx |
| OS-EXT-SRV-ATTR:instance_name | instance-0001b0bd |
| OS-EXT-STS:power_state | 1 |
| OS-EXT-STS:task_state | - |
| OS-EXT-STS:vm_state | active |
| OS-SRV-USG:launched_at | 2019-08-26T01:12:52.000000 |
| OS-SRV-USG:terminated_at | - |
| accessIPv4 | |
| accessIPv6 | |
| config_drive | True |
| created | 2019-08-26T00:51:28Z |
| flavor | m1.medium (0911497d-2ae0-42a8-8ad3-5bc4a7eb0ec1) |
| hostId | 9b5388ea10622a3c0d9bb99eb998cb529e43517282d38f5bd93417be |
| id | 5c56d203-4991-49ad-b956-0da6bf83902e |
~~~

Expected result
===============
After resizing the VM, it will be booted on the specified host

Actual result
=============
Image metadata ignored and scheduled VM boots

Environment
===========
1. Exact version of OpenStack you are running.
* Community OpenStack Rocky

2. Which hypervisor did you use?
* CentOS 7

3. Which networking type did you use?
* Neutron ML2 Driver

[Sylvain Bauza (sylvain-bauza)]

Could you please give us sanitized (and ideally at a DEBUG level) n-sch and n-conductor logs so we could see why it looks it doesn't run for you ?

Putting the state to Incomplete, please put back to New once you reply.

[Launchpad Janitor (janitor)]

[Expired for OpenStack Compute (nova) because there has been no activity for 60 days.]