> can I know a use case for this 'live copy metadata or ' the 'only way > to access device tags when hot-attach? my thought is this is one time > thing in cloud-init side either through metatdata service or config > drive and won't be used later? then why I need a live copy? If I do something like this: nova interface-attach --tag=data-network --port-id=foo myserver Then we update the device metadata live, which is visible immediately via the metadata service. However, in config drive, that only gets updated the next time the drive is generated (which may be a long time away). For more information on device metadata, see: https://specs.openstack.org/openstack/nova-specs/specs/mitaka/approved/virt-device-role-tagging.html Further, some of the drivers support setting the admin password securely via metadata, which similarly requires the instance pulling updated information out, which wouldn't be available in the config drive. For reference: https://github.com/openstack/nova/blob/master/nova/virt/libvirt/driver.py#L1985-L1993 --Dan