Comment 0 for bug 2073365

Steps to reproduce
==================
A chronological list of steps which will bring off the
issue you noticed:
* added a KVM Host and remove, repeat this steps 2-3 times, to let the nova services table have records that has marked as deleted.
* add the same KVM Host back.
* Deploy a VM on this KVM Host.
* Select it and trying to doing a resize, then it always reports 409 error.

Expected result
===============
resize should be succeed

Actual result
=============
What happened instead of the expected result?
How did the issue look like?

Environment
===========
1. Openstack version 2023.1(Antelope)

Cause Analysis
==============
resize reporting 409, Service Unavailable, is because the check_instance_host raises exception.ServiceUnavailable().

    @check_instance_host(check_is_up=True)
    def resize(self, context, instance, flavor_id=None, clean_shutdown=True,
               host_name=None, auto_disk_config=None):
        """Resize (ie, migrate) a running instance.

def check_instance_host(check_is_up=False):
    """Validate the instance.host before performing the operation.

    At a minimum this method will check that the instance.host is set.

    :param check_is_up: If True, check that the instance.host status is UP
        or MAINTENANCE (disabled but not down).
    :raises: InstanceNotReady if the instance.host is not set
    :raises: ServiceUnavailable if check_is_up=True and the instance.host
        compute service status is not UP or MAINTENANCE
    """
    def outer(function):
        @functools.wraps(function)
        def wrapped(self, context, instance, *args, **kwargs):
            if not instance.host:
                raise exception.InstanceNotReady(instance_id=instance.uuid)
            if check_is_up:
                # Make sure the source compute service is not down otherwise we
                # cannot proceed.
                service = [
                    service for service in instance.services
                        if service.binary == 'nova-compute'][0]
                if not self.servicegroup_api.service_is_up(service):
                    # ComputeServiceUnavailable would make more sense here but
                    # we do not want to leak hostnames to end users.
                    raise exception.ServiceUnavailable()
            return function(self, context, instance, *args, **kwargs)
        return wrapped
    return outer
        return host_status

Debugging shows the instance.services included the services records that already deleted; why it should not.

(Pdb) p instance.services
ServiceList(objects=[Service(a2b948f2-6d82-4d5c-bf67-9d7b45cf9868),Service(50b280ac-9ed6-4bf3-a87f-1f8697d87966),Service(ade10449-24ad-4535-bbaa-38fbb79956fc),Service(dc0fa50d-83ab-4ca3-bdde-68e527a35a8d),Service(2191a868-5e66-4758-b7f1-67b0c4c43294)])

MariaDB [nova]> select * from services where host='kvmcore14';
+---------------------+---------------------+---------------------+----+-----------+--------------+---------+--------------+----------+---------+-----------------+---------------------+-------------+---------+--------------------------------------+
| created_at | updated_at | deleted_at | id | host | binary | topic | report_count | disabled | deleted | disabled_reason | last_seen_up | forced_down | version | uuid |
+---------------------+---------------------+---------------------+----+-----------+--------------+---------+--------------+----------+---------+-----------------+---------------------+-------------+---------+--------------------------------------+
| 2024-07-02 01:42:07 | 2024-07-02 08:56:51 | 2024-07-02 08:56:58 | 10 | kvmcore14 | nova-compute | compute | 861 | 0 | 10 | NULL | 2024-07-02 08:56:51 | 0 | 51 | a2b948f2-6d82-4d5c-bf67-9d7b45cf9868 |
| 2024-07-02 09:20:37 | 2024-07-04 01:19:48 | 2024-07-04 01:19:54 | 16 | kvmcore14 | nova-compute | compute | 4742 | 0 | 16 | NULL | 2024-07-04 01:19:48 | 0 | 51 | 50b280ac-9ed6-4bf3-a87f-1f8697d87966 |
| 2024-07-09 10:09:40 | 2024-07-10 00:47:44 | 2024-07-10 00:48:12 | 17 | kvmcore14 | nova-compute | compute | 1733 | 0 | 17 | NULL | 2024-07-10 00:47:44 | 0 | 51 | ade10449-24ad-4535-bbaa-38fbb79956fc |
| 2024-07-10 01:04:46 | 2024-07-10 01:04:57 | 2024-07-10 01:05:21 | 19 | kvmcore14 | nova-compute | compute | 1 | 0 | 19 | NULL | 2024-07-10 01:04:57 | 0 | 51 | dc0fa50d-83ab-4ca3-bdde-68e527a35a8d |
| 2024-07-10 01:22:57 | 2024-07-10 02:13:43 | NULL | 20 | kvmcore14 | nova-compute | compute | 100 | 0 | 0 | NULL | 2024-07-10 02:13:43 | 0 | 51 | 2191a868-5e66-4758-b7f1-67b0c4c43294 |
+---------------------+---------------------+---------------------+----+-----------+--------------+---------+--------------+----------+---------+-----------------+---------------------+-------------+---------+--------------------------------------+
5 rows in set (0.002 sec)