Kubernetes Networking [Level-8: kube-proxy / iptables / IPVS / eBPF]
This is Level 8 of our Kubernetes networking series, and it's where we finally go inside the Service dataplane . Back in Level 3, we learned that a client Pod talks to a Service's ClusterIP, which somehow routes traffic to a backend Pod: Client Pod → Service (10.96.120.50:80) → Backend Pod (10.244.1.10:80) We deliberately left one question unanswered until now: how does traffic sent to that…
The article delves into the intricacies of Kubernetes networking, specifically focusing on the Service dataplane, which is the pathway through which traffic is routed from a client Pod to a backend Pod via a Service IP. Historically, this process was managed by kube-proxy, a component that created iptables rules on each node to translate the Service IP into the actual IP of a backend Pod.
However, modern clusters have evolved, offering alternative solutions such as IPVS (IP Virtual Server) and eBPF (extended Berkeley Packet Filter), which can potentially replace or supplement kube-proxy. The article also discusses the differences between DNAT (Destination Network Address Translation) and SNAT (Source Network Address Translation), the role of IPVS in load balancing across endpoints, and the significance of eBPF in modern Kubernetes networking, highlighting its ability to enhance the functionality and efficiency of kube-proxy.
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