Hacking Kubernetes

Chapter 5. Networking

In this chapter we will focus on networking aspects of your workloads. We will first review the defaults that Kubernetes proper comes equipped with and what else is readily available due to integrations. We cover networking topics including East-West and North-South traffic—that is, intra-pod and inter-pod communication, communication with the worker node (hosts), cluster-external communication, workload identity, and encryption on the wire.

In the second part of this chapter we have a look at two more recent additions to the Kubernetes networking toolbox: service meshes and the Linux kernel extension mechanism eBPF. We try to give you a rough idea if, how, and where you can, going forward, benefit from both.

As you can see in Figure 5-1, there are many moving parts in the networking space.

Figure 5-1. Network layer model

The good news is that most if not all of the protocols should be familiar to you, since Kubernetes uses the standard Internet Engineering Task Force (IETF) suite of networking protocols, from the Internet Protocol to the Domain Name System (DNS). What changes, really, is the scope and generally the assumptions about how the protocols are used. For example, when deployed on a worldwide scale, it makes sense to make the time-to-live (TTL) of a DNS record months or longer.

In the context of a container that may run for hours or days at best, ...