DNS

In our old OpenStack DNS entries for Floating IP Addresses where generated automatically. This was not a feature that was offered by OpenStack but by a dirty hacked script. Since OpenStack V2 is intended to be a clean installation not consisting of any dirty hacks or custom patches, this feature is no longer present. Now we have to rely on functionality offered by the OpenStack community as is. The new functionality is actually provided by an OpenStack plugin called Designate.

Changed Paradigm of DNS Entries when using Designate

While prior DNS entries where seen as associated to a particular Virtual Machine, now DNS entries are associated to the Floating IP.

This means that:

• DNS Names are created with the Floating IP
• The DNS entry moves with the Floating IP (if you detach and reattach it to a different VM)

Prerequisites

Before you can create a domain name for your Floating IP, you have to set up a DNS Zone for your project-space. As a convention you have to set the zone name to yourprojectspace.osc.eonerc.rwth-aachen.de. (yes, the point at the end is needed). Also provide your email address and feel encouraged to provide a description.

Here is an example configuration for a project-space called test

Allocate a Floating IP with DNS Association

When you have set up your zone you can create a set of Floating IP and DNS name.

In this example, we used the zone we have set up in the prerequisites test.osc.eonerc.rwth-aachen.de. and a hostname part database, indicating that this ip is ment to be used for the VM carrying some database. The complete DNS name of the Floating IP then is database.test.osc.eonerc.rwth-aachen.de. Remember whatever VM you associate the Floating IP to will now respond to that DNS name.