kube-proxy Role

kube-proxy is a network proxy component that runs on each node in a Kubernetes cluster and manages network rules to route virtual IPs (Cluster IP) provided by Services to actual Pods.

In other words, it's a network manager that connects Services and Pods.

1. Service -> Pod Routing #

It creates essential network rules to forward requests coming to a Service's ClusterIP to the actual Pod IP.

1. iptables mode
2. ipvs mode

It generates routing rules using one of the two methods above.

Pod Endpoint Change Detection and Automatic Rule Updates #

When a new Pod is created, it's added to the routing targets, and when it dies, it's immediately removed from the routing targets.

If it's not in a Ready state, it's excluded from traffic delivery targets.

In other words, kube-proxy also keeps the list of Pods behind a Service up-to-date.

NodePort Implementation #

A NodePort Service opens a specific port on all nodes.

kube-proxy also opens this port and forwards requests coming to that port to the appropriate Pod.

Load Balancing #

When there are multiple Pods behind it, it distributes traffic evenly.

• Round robin ipvs
• Random iptables
• Session-based option ipvs

This means that without kube-proxy, a Service would be an empty shell with just an IP, unable to deliver traffic to Pods.

kube-proxy = Network routing manager that connects Services to actual Pods Definition: Node-level network proxy Key roles:

• Service virtual IP → Pod actual IP routing
• Rule updates based on endpoint (Pod) changes
• NodePort handling
• Traffic load balancing