[openstack-dev] [nova] What is the goal of AggregateImagePropertiesIsolation filter?
chris.friesen at windriver.com
Thu Oct 5 14:16:50 UTC 2017
On 10/05/2017 03:47 AM, Kekane, Abhishek wrote:
> So the question here is, what is the exact goal of
> AggregateImagePropertiesIsolation' scheduler filter: - Is it one of the following:-
> 1. Matching all metadata of host aggregate with image properties.
> 2. Matching image properties with host aggregate metadata.
> If we decide that actual goal of 'AggregateImagePropertiesIsolation' filter is
> as pointed in #1, then a small correction is required to return False if image
> property is not present from the host aggregate metadata.
The name of the filter includes "Isolation", so I think the intent was to
accomplish #1. However, as you point out it only fails the filter if both the
aggregate and the image have the same key but different values and so the
isolation is imperfect.
At the same time we have the AggregateInstanceExtraSpecsFilter (which ensures
that any keys in the flavor extra-specs must be present in the aggregate).
Since keys can be specified in either the flavor or the image, it could be
confusing that the behaviour is different between these two filters. At the
same time we don't want to break existing users by modifying the behaviour of
the existing filters. Given this it might make sense to create a new filter
which unifies the checks and behaves the same whether the key is specified in
the image or the flavor, with some way to toggle whether we want strict
isolation or not (so that we can ensure only "special" flavors/images are
allowed to use aggregates with specific limited resources).
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