> The problem isn't just checking the traits in the nested resource > provider. We also need to ensure the trait in the exactly same child > resource provider. No, we can't get "granular" with image traits. We accepted this as a limitation for the spawn aspect of this spec [1], for all the same reasons [2]. And by the time we've spawned the instance, we've lost the information about which granular request groups (from the flavor) were satisfied by which resources - retrofitting that information from a new image would be even harder. So we need to accept the same limitation for rebuild. [1] "Due to the difficulty of attempting to reconcile granular request groups between an image and a flavor, only the (un-numbered) trait group is supported. The traits listed there are merged with those of the un-numbered request group from the flavor." (http://specs.openstack.org/openstack/nova-specs/specs/rocky/approved/glance-image-traits.html#proposed-change) [2] https://review.openstack.org/#/c/554305/2/specs/rocky/approved/glance-image-traits.rst@86