On reboot, minions hostname would change, causing issue querying Openstack API and registering with kube-apiserver.

This is due to a bug in cloud-init which has been patched but apparently not widely distributed.

Should be harmless on unaffected systems.
https://bugs.launchpad.net/cloud-init/+bug/1246485
http://blog.oddbit.com/2014/12/10/cloudinit-and-the-case-of-the-changing-hostname/