'Get the node associated with the instance.
Check with the Ironic service that this instance is associated with a
node, and return the node.'

def _validate_instance_and_node(self, instance):

    try:
        return self.ironicclient.call('node.get_by_instance_uuid', instance.uuid, fields=_NODE_FIELDS)
    except ironic.exc.NotFound:
        raise exception.InstanceNotFound(instance_id=instance.uuid)
