Handle upgrades with drop of AvailabilityZoneFilter in bobcat

[Corey Bryant]

The AvailabilityZoneFilter was removed from nova in bobcat.

The was removed from upstream nova in the 2023.2 cycle
via commit 5edd805fe2395f35ecdfe5b589a51dc00565852f.

The nova release note states:

The ``AvailabilityZoneFilter`` was deprecated for removal
in 24.0.0 (Xena) and has now been removed.
The functionality of the``AvailabilityZoneFilter`` has been
replaced by the``map_az_to_placement_aggregate`` pre-filter.
The pre-filter was introduced in 18.0.0 (Rocky) and enabled
by default in 24.0.0 (Xena). This pre-filter is now always
enabled and the ``[scheduler] query_placement_for_availability_zone``
config option has been removed.

There are likely migration considerations here for the charms where placement aggregates will need updating on upgrade to bobcat or C (SLURP) in order for users to target availability zones on instance creation (needs testing). New bobcat or C deploys should be okay [1] (but also needs testing).

Relevant docs:

https://docs.openstack.org/nova/latest/admin/availability-zones.html#availability-zones-with-placement
https://docs.openstack.org/nova/latest/admin/aggregates.html#aggregates-in-placement

[1] Note (from 2nd link above):

The nova-api service attempts (as of nova 18.0.0) to automatically mirror the association of a compute host with an aggregate when an administrator adds or removes a host to/from a nova host aggregate. This should alleviate the need to manually create those association records in the placement API using the openstack resource provider aggregate set CLI invocation.

I started a review here: https://review.opendev.org/c/openstack/charm-nova-cloud-controller/+/895840

[Corey Bryant (corey.bryant)]

I tested the following successfully for this change:

Note: Fix for the following is required for upgrades: https://bugs.launchpad.net/charm-nova-cloud-controller/+bug/2037751

== upgrade ==

# deploy jammy-zed
openstack aggregate create ag-zed
openstack aggregate set --property availability_zone=az-zed ag-zed
openstack aggregate add host ag-zed $(openstack hypervisor list --column 'Hypervisor Hostname' --sort-column 'Hypervisor Hostname' --format value | grep 14)
openstack server create az-zed-on-zed --availability-zone az-zed --image cirros --flavor m1.tiny --nic net-id=private
openstack server show --column hypervisor_hostname --column availability_zone az-zed-on-zed

# upgrade to antelope
openstack aggregate create ag-antelope
openstack aggregate set --property availability_zone=az-antelope ag-antelope
openstack aggregate add host ag-antelope $(openstack hypervisor list --column 'Hypervisor Hostname' --sort-column 'Hypervisor Hostname' --format value | grep 15)
openstack server create az-antelope-on-antelope --availability-zone az-antelope --image cirros --flavor m1.tiny --nic net-id=private
openstack server create az-zed-on-antelope --availability-zone az-zed --image cirros --flavor m1.tiny --nic net-id=private
openstack server show --column hypervisor_hostname --column availability_zone az-antelope-on-antelope
openstack server show --column hypervisor_hostname --column availability_zone az-zed-on-antelope

# upgrade to bobcat
openstack aggregate create ag-bobcat
openstack aggregate set --property availability_zone=az-bobcat ag-bobcat
openstack aggregate add host ag-bobcat $(openstack hypervisor list --column 'Hypervisor Hostname' --sort-column 'Hypervisor Hostname' --format value | grep 16)
openstack server create az-bobcat-on-bobcat --availability-zone az-bobcat --image cirros --flavor m1.tiny --nic net-id=private
openstack server create az-antelope-on-bobcat --availability-zone az-antelope --image cirros --flavor m1.tiny --nic net-id=private
openstack server create az-zed-on-bobcat --availability-zone az-zed --image cirros --flavor m1.tiny --nic net-id=private
openstack server show --column hypervisor_hostname --column availability_zone az-bobcat-on-bobcat
openstack server show --column hypervisor_hostname --column availability_zone az-antelope-on-bobcat
openstack server show --column hypervisor_hostname --column availability_zone az-zed-on-bobcat

== new bobcat deploy ==

# deploy jammy-bobcat
openstack aggregate create ag-bobcat
openstack aggregate set --property availability_zone=az-bobcat ag-bobcat
openstack aggregate add host ag-bobcat $(openstack hypervisor list --column 'Hypervisor Hostname' --sort-column 'Hypervisor Hostname' --format value | grep 16)
openstack server create az-bobcat-on-bobcat --availability-zone az-bobcat --image cirros --flavor m1.tiny --nic net-id=private
openstack server show --column hypervisor_hostname --column availability_zone az-bobcat-on-bobcat

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/charm-guide/+/897070

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/charm-nova-cloud-controller/+/895840
Committed: https://opendev.org/openstack/charm-nova-cloud-controller/commit/5cf66c87c797e4f7549bc7cd9f5d57c624d30d00
Submitter: "Zuul (22348)"
Branch: master

commit 5cf66c87c797e4f7549bc7cd9f5d57c624d30d00
Author: Corey Bryant <email address hidden>
Date: Tue Sep 19 14:00:33 2023 -0400

    Drop AvailabilityZoneFilter inline with upstream removal

    The was removed from upstream nova in the 2023.2 cycle
    via commit 5edd805fe2395f35ecdfe5b589a51dc00565852f.

    The nova release note states:

    The ``AvailabilityZoneFilter`` was deprecated for removal
    in 24.0.0 (Xena) and has now been removed.
    The functionality of the``AvailabilityZoneFilter`` has been
    replaced by the``map_az_to_placement_aggregate`` pre-filter.
    The pre-filter was introduced in 18.0.0 (Rocky) and enabled
    by default in 24.0.0 (Xena). This pre-filter is now always
    enabled and the ``[scheduler] query_placement_for_availability_zone``
    config option has been removed.

    This change also syncs the charm-helpers change from:
    https://github.com/juju/charm-helpers/pull/850

    Closes-Bug: #2037751
    Closes-Bug: #2036766
    Change-Id: I315900a7e32ec66b27fa69961e9b7dcb9fa1f949

[Corey Bryant (corey.bryant)]

Related doc updates https://review.opendev.org/c/openstack/charm-guide/+/897070

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/charm-guide/+/897070
Committed: https://opendev.org/openstack/charm-guide/commit/16b35ea4b2c5de7e7de2e8fdcf05e61322f30a32
Submitter: "Zuul (22348)"
Branch: master

commit 16b35ea4b2c5de7e7de2e8fdcf05e61322f30a32
Author: Corey Bryant <email address hidden>
Date: Mon Oct 2 12:06:02 2023 -0400

    Nova AvailabilityZoneFilter removal in Bobcat

    Add documentation discussing AvailabilityZoneFilter removal in
    Bobcat, including expected behavior and commands for determining
    whether host aggregates have been mirrored to placement aggregates.

    Closes-Bug: #2036766
    Change-Id: I5543c960791617d2e7083aa989d97f3dc233ee86