Open Stack

On Fri, 2013-02-15 at 12:22 +0200, Alessandro Pilotti wrote:
> Hi guys,
> 
> As discussed with russelb and during the OpenStack Hyper-V meetings, it'd be a great to move compute driver specific onfigurations from nova.conf's [DEFAULT] group to a driver specific group (e.g. [LIBVIRT], [HYPERV], etc).
> 
> We already added new options in Grizzly to the [HYPERV] group and for consistency, before closing Grizzly, we'd like to move the existing Hyper-V ones added in Folsom there as well.
> 
> This approach could be IMO applied to all the drivers (in the Havana timeframe at this point, I guess).
> The obvious issue is that breaking backwards compatibility is not an option.
> 
> openstack.common.cfg.Opt() offers a "deprecated_name" argument, but AFAIK this applies only for options belonging to the same group:
> https://github.com/openstack/nova/blob/master/nova/openstack/common/cfg.py#L518
> 
> What about adding a "deprecated_group" as well or a "<group>.<option>" syntax for "deprecated_name"? This way we could handle the transition smoothly.

Coincidentally, I have a WIP oslo-config branch for this:

  https://github.com/markmc/oslo-config/commits/deprecated-group

It's getting pretty tight for Grizzly, but I hope to push this up for
review today.

> Getting back to the specific Hyper-V case, if deprecated options are not possible at this stage, we'd prefer to rename them anyway now. The Hyper-V support is far more complete in this release then it was in Folsom. Moving or deprecating the options in Havana will create way more confusion than doing it now.
> 
> Here are the Hyper-V config options that need to be moved to the [HYPERV] group:
> https://github.com/openstack/nova/blob/master/nova/virt/hyperv/vmops.py#L43
> https://github.com/openstack/nova/blob/master/nova/virt/hyperv/volumeops.py#L35
> 
> Any additional ideas?

Usually, we avoid breaking existing configurations. But, in the case of
hyper-v, I'd be fine with you guys saying "we did't have many users in
Folsom, so backwards compat isn't a big concern".

Cheers,
Mark.