Open Stack

On Thu, 2012-08-16 at 20:22 -0600, Jim Fehlig wrote:
> While merging the recent ComputeFilter additions with the ArchFilter, I
> spent too much time agonizing over the name ArchFilter, which I was now
> making filter on more than just architecture.  ComputeCapabilitiesFilter
> seems like better name, but this is already taken.
> 
> Looking at ComputeCapabilitiesFilter again, I realize it is filtering on
> some of the same properties as the combined ArchFilter [1], but from a
> different source.  IIUC, ComputeCapabilitiesFilter filters on properties
> that originate from the instance type/flavor.  The combined ArchFilter
> filters on properties that originate from the image.  It seems this
> could be a source of confusion for users, but at the same time seems
> necessary, particularly for properties such as architecture, preferred
> hypervisor and virtual machine mode, which I tend to think are
> properties of an image more so than a flavor.  E.g. I could select my
> "Xen arm" flavor, but unless I also selected a "Xen arm" image, I could
> have an instance that doesn't boot.
> 
> Do folks have any issues with filters using both image and flavor
> properties?  Being relatively new here, this may very well be intended
> :).  If so, I'd like to change the name of ArchFilter to better reflect
> its new additions.  What do you think of ImagePropertiesFilter?  It
> filters hosts based on compute properties defined on the image.  Or
> ImageComputePropertiesFilter, to accommodate a future class of
> filterable image properties?

Ok, stepping back for a minute. Before your patch, we had:

ComputeFilter
  simply matches enabled compute hosts

ArchFilter
  match the architecture from the image properties against the compute 
  node's permitted_instance_types

  it's using instance_properties['architecture'] which is taken from the
  image's architecture property in _create_instance() - see how
  base_options is populated

  permitted_instance_types is just the list of guest archs

ComputeCapabilitiesFilter
  matches properties defined in an instance type's extra specs against 
  compute capabilities

AggregateInstanceExtraSpecsFilter
  matches properties defined in an instance type's extra specs against
  admin-defined properties on a host aggregate

And then you added:

  match the arch, hypervisor type and vm type from the image properties 
  against those supported by the compute node

It looks to me like what you've added is a complete superset of
ArchFilter - i.e. if you just specify the architecture property on the
image, the behaviour should be identical.

So, IMHO, it should be fine to move your new matching into
ImagePropertiesFilter and just delete ArchFilter.

Cheers,
Mark.