'Initialize new metadata for a snapshot of the given instance.
:param instance: nova.objects.instance.Instance object
:param name: string for name of the snapshot
:param extra_properties: dict of extra metadata properties to include
:returns: the new instance snapshot metadata'

def _initialize_instance_snapshot_metadata(self, instance, name, extra_properties=None):

    image_meta = utils.get_image_from_system_metadata(instance.system_metadata)
    image_meta.update({'name': name, 'is_public': False})
    properties = image_meta['properties']
    for key in CONF.non_inheritable_image_properties:
        properties.pop(key, None)
    properties.update((extra_properties or {}))
    return image_meta
