OpenShift Master DNS Operator

What is this?

This is an operator that manages etcd DNS entries for masters in an OpenShift cluster.

Why is it needed?

Part of the work of recovering a master that has been destroyed or restarted is updating the DNS entry that is used to identify it as a member of the etcd cluster. These are entries in the form of [cluster-name]-etcd-[index].[domain]. In AWS, these are records in the private Route53 zone that belongs to the cluster. Automatically updating these makes the job of recovering the master much simpler.

How does it do it?

The operator leverages external-dns to update DNS records in the cloud provider. It watches cluster-api Machine resources and obtains internal IPs from them. It then uses those IPs to create a custom resource with machine names and addresses.