simplestreams should avoid pruning images in use

[David Ames]

For live migration in openstack to work the original image used for an instance must still be available in glance as nova will use the original image in the process of migration.

Right now tools/sstream-mirror-glance will prune based on the --max and --keep switches. There needs to be a switch that takes into account images that are deployed and avoid pruning them.

[David Ames (thedac)]

A possible approach:

    server_list = novaclient.servers.list(search_opts={'all_tenants': 1})
    for server in server_list:
        try:
            # These images could then be "protected"
            glanceclient.images.update(server.image.get('id'), protected=True)
        except AttributeError:
            pass

Then pruning attempts can then be try/excepted based on glanceclient.exc.HTTPForbidden

Note: The novaclient search for all tenants requires elevated privileges.