In the first post of this series I looked at how kubernetes employs a combination of virtual network devices and routing rules to allow a pod running on one cluster node to communicate with a pod running on another, as long as the sender knows the receiver’s pod network IP address. If you aren’t already familiar with how pods communicate then it’s worth a read before continuing. Pod networking in a cluster is neat stuff, but by itself it is insufficient to enable the creation of durable systems. That’s because pods in kubernetes are ephemeral. You can use a pod IP address as an endpoint but there is no guarantee that the address won’t change the next time the pod is recreated, which might happen for any number of reasons.