nova-scheduler will crash at startup if placement is not up

[Dan Smith]

This is the same problem as https://bugs.launchpad.net/nova/+bug/1846820 but for scheduler. Because we initialize our placement client during manager init, we will crash (and loop) on startup if keystone or placement are down. Example trace:

Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova.scheduler.client.report [None req-edf51111-6f86-4910-a458-72decae8e451 None None] Failed to initialize placement client (is keystone available?): openstack.exceptions.NotSupported: The placement service for 192.168.122.154:RegionOne exists but does not have any supported versions.
Mar 22 15:54:39 jammy nova-scheduler[119746]: CRITICAL nova [None req-edf51111-6f86-4910-a458-72decae8e451 None None] Unhandled error: openstack.exceptions.NotSupported: The placement service for 192.168.122.154:RegionOne exists but does not have any supported versions.
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova Traceback (most recent call last):
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova File "/usr/local/bin/nova-scheduler", line 10, in <module>
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova sys.exit(main())
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova File "/opt/stack/nova/nova/cmd/scheduler.py", line 47, in main
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova server = service.Service.create(
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova File "/opt/stack/nova/nova/service.py", line 252, in create
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova service_obj = cls(host, binary, topic, manager,
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova File "/opt/stack/nova/nova/service.py", line 116, in __init__
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova self.manager = manager_class(host=self.host, *args, **kwargs)
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova File "/opt/stack/nova/nova/scheduler/manager.py", line 70, in __init__
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova self.placement_client = report.report_client_singleton()
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova File "/opt/stack/nova/nova/scheduler/client/report.py", line 91, in report_client_singleton
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova PLACEMENTCLIENT = SchedulerReportClient()
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova File "/opt/stack/nova/nova/scheduler/client/report.py", line 234, in __init__
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova self._client = self._create_client()
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova File "/opt/stack/nova/nova/scheduler/client/report.py", line 277, in _create_client
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova client = self._adapter or utils.get_sdk_adapter('placement')
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova File "/opt/stack/nova/nova/utils.py", line 984, in get_sdk_adapter
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova return getattr(conn, service_type)
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova File "/usr/local/lib/python3.10/dist-packages/openstack/service_description.py", line 87, in __get__
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova proxy = self._make_proxy(instance)
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova File "/usr/local/lib/python3.10/dist-packages/openstack/service_description.py", line 266, in _make_proxy
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova raise exceptions.NotSupported(
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova openstack.exceptions.NotSupported: The placement service for 192.168.122.154:RegionOne exists but does not have any supported versions.
Mar 22 15:54:39 jammy nova-scheduler[119746]: ERROR nova

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/nova/+/878238

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/nova/+/878238
Committed: https://opendev.org/openstack/nova/commit/d37cca361a4d575311318cb870da40079eb1617c
Submitter: "Zuul (22348)"
Branch: master

commit d37cca361a4d575311318cb870da40079eb1617c
Author: Dan Smith <email address hidden>
Date: Wed Mar 22 08:20:58 2023 -0700

    Make scheduler lazy-load the placement client

    Like we did for conductor, this makes the scheduler lazy-load the
    placement client instead of only doing it during __init__. This avoids
    a startup crash if keystone or placement are not available, but
    retains startup failures for other problems and errors likely to be
    a result of misconfigurations.

    Closes-Bug: #2012530
    Change-Id: I42ed876b84d80536e83d9ae01696b0a64299c9f7

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 28.0.0.0rc1 release candidate.