[openstack-dev] Moving nova.conf compute driver options from [DEFAULT] to [DRIVER_NAME]

John Garbutt john at johngarbutt.com
Mon Feb 18 11:00:23 UTC 2013


+1 for XenAPI doing a similar thing, if we can get the backwards
compatibility right.
I feel we should create a config migration tool to help with this move.

We should really stop doing these changes, but it seems necessary to
let the config file scale.

I think the puppet guys did some work to split up the configuration.
Has anyone taken a look at that work recently?

John

On 16 February 2013 00:59, Alessandro Pilotti <ap at pilotti.it> wrote:
> 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.
>
>
> That's perfect! Please let me know if you can make it for Grizzly, I'd be
> glad to test it. I'll wait to send my patch for review in the meantime, as
> with yours any compatibility issue would be solved.
>
> 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".
>
>
> Folsom was the first release for us (I'm not counting the pre Essex driver)
> with the initial Nova support. For Grizzly we're quite overwhelmed by
> customers response, especially after we added Quantum and another gazillion
> features to Nova, Cinder, our Windows Cloud-Init etc. So it's a good moment
> for doing some small cleanup by moving those few options to the proper
> place. :-)
>
> Thanks!
>
> Alessandro
>
>
>
> On Feb 15, 2013, at 13:07 , Mark McLoughlin <markmc at redhat.com> wrote:
>
> 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.
>
>
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John Garbutt MA (Cantab) MBCS
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