The metadata service is accessible from each cloud server and provides metadata via http. It provides a few basic data, such as hostname, instance-id and ssh keys, but can also provide custom user data.
The interface is compatible with the Amazon EC2 metadata service. It’s accessible from each server at http://169.254.169.254.
$ curl http://169.254.169.254/latest/meta-data/ hostname instance-id instance-type local-hostname local-ipv4 placement/ $ curl http://169.254.169.254/latest/meta-data/instance-id srv-sz59
See the user data guide for more examples of using the meta data service.