Open Stack

On Wed, 2013-02-06 at 16:10 +0000, Daniel P. Berrange wrote:
> On Wed, Feb 06, 2013 at 10:46:52AM -0500, Mark McLoughlin wrote:
> > On Wed, 2013-02-06 at 15:22 +0000, Daniel P. Berrange wrote:
> > > The only way we can do this is if we do *NOT* require the use of
> > > classnames in config parameters. Instead we should treat all these
> > > config parameters as being more like enumerations, and map those to
> > > classnames internally
> > > 
> > > eg for the compute_driver instead of having the user set
> > > 
> > >   compute_driver=nova.virt.libvirt.LibvirtDriver
> > > 
> > > they would do
> > > 
> > >   compute_driver=libvirt 
> > 
> > I think there's already good consensus on this and the idea is to use
> > entry points and stevedore to achieve it.
> > 
> > See:
> > 
> >   https://blueprints.launchpad.net/nova/+spec/entrypoints-plugins
> >   https://review.openstack.org/11027
> >   https://review.openstack.org/15030
> 
> Heh, I've even seen that blueprint before, but it was hard to understand
> just what it was on about. A etherpad transcript of a conversation that
> you weren't present for, doesn't make a nice design doc for blueprint :-(
> 
> > The end result is exactly that
> > 
> >   compute_driver=libvirt
> > 
> > will work, along with backwards compat for the original name.
> > 
> > It just needs to be resurrected and finished off.
> 
> Indeed, it looks like that is definitely something to have as a
> priority item. Even if those patches were resurrected it looks
> like quite alot more work is needed, give that they only tackle
> 3 out of 44+ config parameters!
> 
> Do we have any official position on config file upgrade support
> at this time ?  It would be helpful to reviewers if they could
> clearly identify whether a proposed config change is acceptable
> or not from an upgrade POV, since currently people are holding
> different changes to different standards before approval

"Official position", heh.

I'd say that we should not be changing configuration options in
incompatible ways without a deprecation period (of a release cycle)
unless we're talking about a really obscure config option that is highly
unlikely to have been used by real users.

Got examples of where we didn't follow that general rule?

Cheers,
Mark.