Note: Since writing this post, I joined Google. We have released a feature called IP Aliases that addresses the problem described in this article, and much more.
I recently ran into a problem while using Google Container Engine (GKE), the managed Kubernetes by Google. This lead me to an interesting solution that can be used for a large range of issues you could encounter in Kubernetes.
The Problem I was unsuccessfully trying to have my pods communicate with an application available through a VPN: everything was working as expected from a VM but the pods in the GKE cluster had no network connectivity with the services on the other side of the VPN.