Comment 20 for bug 1526283

Reviewed: https://review.openstack.org/407491
Committed: https://git.openstack.org/cgit/openstack/ironic/commit/?id=9bc06783ecaff5eef58535904abc12ea15982329
Submitter: Jenkins
Branch: master

commit 9bc06783ecaff5eef58535904abc12ea15982329
Author: Grzegorz Grasza <email address hidden>
Date: Tue Dec 6 13:40:45 2016 +0100

    Add RPC and object version pinning

    To support rolling upgrades, capping of RPC communication and Ironic
    objects is required. Old RPC services and objects may still be running
    while an upgrade is in progress. This makes sure that these old
    services are called and all objects are used in a supported RPC and
    objects version.

    This patch adds the configuration option "pin_release_version". Setting
    this option caps (downgrades) the internal RPC communication to the
    specified version to enable communication with older services. When
    doing a rolling upgrade from version X to Y, set this to X. It defaults
    to using the newest (current) possible RPC behavior and object versions.

    Change-Id: Ie2342d4051f85392a8b10d39ebffc287da57bf2b
    Partial-Bug: #1526283
    Co-Authored-By: Szymon Borkowski <email address hidden>
    Co-Authored-By: Ruby Loo <email address hidden>