Before this, I was stumped with
invalid argument "federation=kubernetes-federation.test." for --federations=federation=kubernetes-federation.test.: federation not a valid federation name
but now
invalid argument "federation=kubernetes-federation.test." for --federations=federation=kubernetes-federation.test.: "kubernetes-federation.test." not a valid domain name: ["must match the regex [a-z0-9]([-a-z0-9]*[a-z0-9])?(\\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)* (e.g. 'example.com')"]
For the domain name queries that fail to match any records in the local
kube-dns cache, we check if the queried name matches the federation
pattern. If it does, we send a CNAME response to the federated name.
For more details look at the comments in the code.