Glance metadefs for OS::Nova::Aggregate should be OS::Nova::HostAggregate

https://github.com/openstack/glance/search?utf8=%E2%9C%93&q=aggregate

The metadata definitions in etc/metadefs allow each namespace to be associated with a resource type in OpenStack. We realized that we used OS::Nova::Aggregate instead of OS::Nova::HostAggregate in Glance. This doesn’t align with Heat [0] or Searchlight [1]. It should be noted that Heat added the resource type after Glance had metadefs.

Glance Issue:

There are a couple of metadef files that have OS::Nova::Aggregate that need to change to OS::Nova::HostAggregate. I see also that OS::Nova: is in one of the db scripts. That script simply adds some initial "resource types" to the database. [3]. It should be noted that there is no hard dependency on that resource type in the DB script. You can add new resource types at any time via API or JSON files and they are automatically added.

The DB will need to be upgraded similar to https://review.openstack.org/#/c/272271/

Horizon Issue:

The aggregate update metadata action should retrieve OS::Nova::HostAggregate instead. The Horizon patch shouldn't merge until the glance patch merges, but there is not an actual hard dependency between the two. Horizon may need to request both in order to be backwards compatible.

[0] http://docs.openstack.org/developer/heat/template_guide/openstack.html#OS::Nova::HostAggregate
[1] https://github.com/openstack/horizon/blob/master/openstack_dashboard/static/app/core/metadata/metadata.service.js#L86
[3] https://github.com/openstack/glance/search?utf8=%E2%9C%93&q=aggregate

The main concern I have is that with the new resource registry, we will register Host Aggregates as OS::Nova::HostAggregate. It just won't align.

The overall changes here are simple, but may have backwards compatibility concerns with older Glance installations.

Finally:

It should be noted that updating namespaces in Glance is already possible with glance-manage. E.g.

/opt/stack/glance$ glance-manage db_load_metadefs etc/metadefs -h
usage: glance-manage db_load_metadefs [-h]
                                      [path] [merge] [prefer_new] [overwrite]

positional arguments:
  path
  merge
  prefer_new
  overwrite

So, you just have to call:

/opt/stack/glance$ glance-manage db_load_metadefs etc/metadefs true true

See also: https://youtu.be/zJpHXdBOoeM