libvirt: deprecated volume_drivers config parameter

[OpenStack Infra]

https://review.openstack.org/117252
commit 79a7029d5f54c82d82dfaff979e62560dd090050
Author: Daniel P. Berrange <email address hidden>
Date: Wed Aug 27 14:47:28 2014 +0100

    libvirt: deprecated volume_drivers config parameter

    In Icehouse the 'vif_driver' parameter was deprecated

      commit 9f6070e194504cc2ca2b7f2a2aabbf91c6b81897
      Author: Lars Kellogg-Stedman <email address hidden>
      Date: Fri Apr 4 14:58:12 2014 -0400

        mark vif_driver as deprecated and log warning

    and then in Juno removed

      commit 7561c8ded211d53e8745d1420a73b82bd0fc35cf
      Author: Daniel P. Berrange <email address hidden>
      Date: Thu Jul 24 11:53:47 2014 +0100

        libvirt: remove 'vif_driver' config parameter

    The 'volumes_drivers' parameter does the same job as the
    'vif_driver' parameter, but for volumes instead of vifs.
    The reasons for deprecating it, in preparation for its
    removal in Lxxxx are thus the same.

    The API for the LibvirtBaseVolumeDriver class is not
    considered to be a public extension point. As such it
    is not required or expected to remain compatible across
    releases.

    The main reason for its existance is for people who are
    developing new cinder drivers, to be able to write out
    of tree nova volume drivers. The recommended practice
    is to instead work in-tree to nova on a branch. This is
    an approach that would be required in order to submit
    the work for review and eventual merge in any case.

    DocImpact: libvirt.volume_drivers config param for
               nova.conf is deprecated, to be removed in
               the Lxxxx release
    Related-bug: #1362191
    Change-Id: I1f884f36e24fe478922671ca3eaf6b7c21fd8a5a

[Andreas Jaeger (jaegerandi)]

Needs regeneration of config tables.

[Tom Fifield (fifieldt)]

This hasn't made it in yet