Comment 3 for bug 1759316

Reviewed: https://review.openstack.org/557506
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=eaf6340847c35ace3b4b681a95b8a79a7a3f2491
Submitter: Zuul
Branch: master

commit eaf6340847c35ace3b4b681a95b8a79a7a3f2491
Author: Matt Riedemann <email address hidden>
Date: Wed Mar 28 16:26:48 2018 -0400

    Log a warning and add nova-status check for old API service versions

    Change Ib984c30543acb3ca9cb95fb53d44d9ded0f5a5c8, which was added
    in Newton when cells v2 was optional, added some transitional code
    to the API for looking up an instance, which didn't rely on instance
    mappings in a cell to find the instance if the minimum nova-osapi_compute
    service version was from before Ocata.

    People have reported this being a source of confusion when upgrading
    from before Ocata, when cells v2 wasn't required, to Ocata+ where cells
    v2 along with the mapping setup is required. That's because they might
    have older nova-osapi_compute service version records in their 'nova'
    (cell) database which makes the API think the code is older than it
    actually is, and results in an InstanceNotFound error.

    This change does two things:

    1. Adds a warning to the compute API code in this scenario to serve
       as a breadcrumb if a deployment hits this issue.

    2. A nova-status check to look for minimum nova-osapi_compute service
       versions across all cells and report the issue as a warning. It's
       not an upgrade failure since we don't know how the nova-api service
       is configured, but leave that investigation up to the deployer.

    This is also written in such a way that we should be able to backport
    this through to stable/ocata.

    Change-Id: Ie2bc4616439352850cf29a9de7d33a06c8f7c2b8
    Closes-Bug: #1759316