Tectonic: Add Stub Domain to kube-dns

Kubernetes added support for configurable private DNS zones (often called “stub domains”) and external upstream DNS nameservers in the 1.6 release. This can be accomplished in Tectonic by creating a ConfigMap for kube-dns within the kube-system namespace. 

First create a file called stubDomains with contents similar to below:

{"example.corp.local": ["13.56.19.37"] }

Then create a secret from this file called kube-dns in the kube-systemnamespace:

kubectl -n kube-system create configmap kube-dns --from-file=./stubDomains

Finally, roll the existing kube-dns pod:

kubectl -n kube-system get pod | grep dns
kube-dns-2425598031-lg5qx

kubectl -n kube-system delete pod kube-dns-2425598031-lg5qx

You can then test the stub domain is reachable from a pod:

kubectl run debug -ti --image=fedora:latest --restart=Never -- /bin/bash -c 'dig example.corp.local'

http://blog.kubernetes.io/2017/04/configuring-private-dns-zones-upstream-nameservers-kubernetes.html

https://www.quora.com/What-is-stub-zone-in-DNS