Open Stack

Hi Ironickers,

There was a big thread here[0] about Cinder, driver removal, and standard
deprecation policy. If you haven't read through it yet, please do before
continuing here. :)

The outcome of that thread is summarized well here.[1]

I know that I previously had a different opinion on this, but I think we
should go roughly the same route, for the sake of the users.

1) A ``supported`` flag for each driver that is True if and only if the driver
   is tested in infra or third-party CI (and meets our third party CI
   requirements).
2) If the supported flag is False for a driver, deprecation is implied (and
   a warning is emitted at load time). A driver may be removed per standard
   deprecation policies, with turning the supported flag False to start the
   clock.
3) Add a ``enable_unsupported_drivers`` config option that allows enabling
   drivers marked supported=False. If a driver is in enabled_drivers, has
   supported=False, and enable_unsupported_drivers=False, ironic-conductor
   will fail to start. Setting enable_unsupported_drivers=True will allow
   ironic-conductor to start with warnings emitted.

It is important to note that (3) does still technically break the standard
deprecation policy (old config may not work with new version of ironic).
However, this is a much softer landing than the original plan. FWIW, I do
expect (but not hope!) this part will be somewhat contentious.

I'd like to hear thoughts and get consensus on this from the rest of the
ironic community, so please do reply whether you agree or disagree.

I'm happy to do the work required (update spec, code patches, doc updates)
when we do come to agreement.

// jim

[0] http://lists.openstack.org/pipermail/openstack-dev/2016-August/101428.html
[1] http://lists.openstack.org/pipermail/openstack-dev/2016-August/101898.html