Kubernetes Networking

What Kubernetes Actually Specifies

A colleague says Kubernetes handles the networking. It does not. It states four requirements and hands the entire implementation to something you installed separately, and almost every confusing thing about Kubernetes networking traces back to that handoff.

What this lesson covers

  • The four requirements: every pod gets an IP, pods communicate without NAT, nodes communicate with pods without NAT, and the IP a pod sees itself as is the IP others see
  • Everything beyond those four is delegated
  • Why knowing exactly where that line sits is the most useful thing in this course
  • The habit of asking which side of the line a behaviour belongs to before going looking for documentation

What is actually happening

Coming soon.

The Kubernetes model versus the CNI's choice

Coming soon.

How it works in practice

Coming soon.

Common failure modes

Coming soon.

What people get wrong

Coming soon.

INTERVIEW QUESTION

What does the Kubernetes network model actually require, and what does it leave entirely to the CNI? Give an example of behaviour engineers commonly attribute to Kubernetes that is really their CNI's choice.

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What the CNI Decides