Comment 8 for bug 1770434

After some debugging it seems that scheduler_utils.setup_instance_group(context, request_spec) in the conductor [3] returns empty host list because the instance query in [4] returns 0 instances for a non empty uuids filter.

Jul 08 19:43:18 ubuntu nova-conductor[7138]: INFO nova.objects.instance_group [None req-6f7cea32-7573-41ee-8eea-0383c5ade138 admin admin] !!! filters {'deleted': False, 'uuid': [u'bbb51826-a9fa-4b66-b976-e9cf1c75175d', u'e6d4be63-8e4e-4be7-ba41-4b56d234a1b4', u'60eb2895-b098-4d5e-b5b2-d9a0686f39bd', u'4c2abe15-40a1-49f7-ada4-11fa9ad7dfef', u'e869bc16-40f8-4fd1-a738-c3015b999cef', u'eeefa697-95ef-445e-985c-da2ae9e6f9e2', u'65614545-9425-4531-8b17-442c6a18dffd', u'9a2c1e5e-0f84-49de-b42e-7baf7935a139', u'c1e22c58-307a-4a67-8e58-90651d42d8e9', u'6680b18b-6e3b-4934-9679-97a61cee35b2', u'd2ac7593-48e0-4aea-813b-b4133acacc53', u'5085065c-a514-4d2b-8060-9ed12f4cb947', u'45b5c17f-b65f-4e1a-abd7-b5b079a4eb60']}
Jul 08 19:43:18 ubuntu nova-conductor[7138]: INFO nova.objects.instance_group [None req-6f7cea32-7573-41ee-8eea-0383c5ade138 admin admin] !!! instances: 0
Jul 08 19:43:18 ubuntu nova-conductor[7138]: INFO nova.scheduler.utils [None req-6f7cea32-7573-41ee-8eea-0383c5ade138 admin admin] !!! group_hosts set([])
Jul 08 19:43:18 ubuntu nova-conductor[7138]: INFO nova.scheduler.utils [None req-6f7cea32-7573-41ee-8eea-0383c5ade138 admin admin] !!! group_info GroupDetails(hosts=set([]), policies=[u'anti-affinity'], members=[u'bbb51826-a9fa-4b66-b976-e9cf1c75175d', u'e6d4be63-8e4e-4be7-ba41-4b56d234a1b4', u'60eb2895-b098-4d5e-b5b2-d9a0686f39bd', u'4c2abe15-40a1-49f7-ada4-11fa9ad7dfef', u'e869bc16-40f8-4fd1-a738-c3015b999cef', u'eeefa697-95ef-445e-985c-da2ae9e6f9e2', u'65614545-9425-4531-8b17-442c6a18dffd', u'9a2c1e5e-0f84-49de-b42e-7baf7935a139', u'c1e22c58-307a-4a67-8e58-90651d42d8e9', u'6680b18b-6e3b-4934-9679-97a61cee35b2', u'd2ac7593-48e0-4aea-813b-b4133acacc53', u'5085065c-a514-4d2b-8060-9ed12f4cb947', u'45b5c17f-b65f-4e1a-abd7-b5b079a4eb60'])
Jul 08 19:43:18 ubuntu nova-conductor[7138]: INFO nova.conductor.manager [None req-6f7cea32-7573-41ee-8eea-0383c5ade138 admin admin] group members=[u'bbb51826-a9fa-4b66-b976-e9cf1c75175d', u'e6d4be63-8e4e-4be7-ba41-4b56d234a1b4', u'60eb2895-b098-4d5e-b5b2-d9a0686f39bd', u'4c2abe15-40a1-49f7-ada4-11fa9ad7dfef', u'e869bc16-40f8-4fd1-a738-c3015b999cef', u'eeefa697-95ef-445e-985c-da2ae9e6f9e2', u'65614545-9425-4531-8b17-442c6a18dffd', u'9a2c1e5e-0f84-49de-b42e-7baf7935a139', u'c1e22c58-307a-4a67-8e58-90651d42d8e9', u'6680b18b-6e3b-4934-9679-97a61cee35b2', u'd2ac7593-48e0-4aea-813b-b4133acacc53', u'5085065c-a514-4d2b-8060-9ed12f4cb947', u'45b5c17f-b65f-4e1a-abd7-b5b079a4eb60'], group hosts=[]

[3] https://github.com/openstack/nova/blob/c0350da4a1607d7aa113caceaefb5d29303c7eed/nova/conductor/manager.py#L711-L713
[4] https://github.com/openstack/nova/blob/c0350da4a1607d7aa113caceaefb5d29303c7eed/nova/objects/instance_group.py#L422