How does traffic physically pass through Service to Pod? What is kube-proxy?

In Kubernetes, traffic to a Pod passes through a Service object, which abstracts access to a group of Pods. This happens as follows:

1. When a client accesses the Service (for example, via ClusterIP or NodePort), the request hits kube-proxy.
2. kube-proxy runs on each node and is responsible for routing traffic to the correct Pod.
3. Depending on the kube-proxy mode (iptables, ipvs, or userspace), it redirects the request to the IP and port of one of the Pods belonging to the Service.

kube-proxy is a Kubernetes component that implements a network proxy and load balancer at the node level. It monitors changes in Services and Endpoints and updates routing rules to ensure traffic correctly reaches the Pods.

Example of operation:

• In iptables mode, kube-proxy adds rules to the iptables table that redirect requests from the Service IP to the Pod IP.
• In ipvs mode, a virtual IP with load balancing is created.

Thus, kube-proxy provides transparent access to Pods through the Service, distributing load and ensuring fault tolerance.