Enforce important properties and predefined values in image schema

Currently Glance allows and recommends users to specify some common image properties that may prove useful to consumers of the image. (http://docs.openstack.org/developer/glance/common-image-properties.html) However, since this is optional and there is no pre-defined set of values, an image may or may not have properties that can later provide an easy mean to query.

There is a blueprint opened against Heat to provision a new server using a constraint based approach for the selection of flavor and image properties. (https://blueprints.launchpad.net/heat/+spec/constraint-based-flavors-and-images)

The optimal way of enabling this new feature is finding an image at runtime using the constraints provided by the user. Therefore, I want to open this new blueprint to request following two features in Glance,
1. Make image properties, at least os_arch, os_type, os_distribution and os_version, as a mandatory properties when add an image to Glance.
2. Have a predefined set of values for such properties to make decisions based querying such properties.

Thomas Spatzier and Fei Long, thanks for your inputs.