A service-mesh style proxy sidecar must reach the application conta…

Question

A service-mesh style proxy sidecar must reach the application container without Service DNS. Why does connecting to localhost work inside the Pod?

Accepted Answer

Containers in a Pod share a network namespace, so they communicate via localhost — Think of the Pod as one network apartment with one phone line: every container picks up on localhost. That shared network namespace is why a proxy sidecar can dial the app on 127.0.0.1.

Answer

Each container receives a unique Pod IP, so localhost is rewritten by kube-proxy

Answer

localhost only works after creating a NodePort on the same node

Answer

Kubernetes injects a default Ingress rule that maps localhost to every container

A service-mesh style proxy sidecar must reach the application container without Service DNS. Why does connecting to localhost work inside the Pod?

Short Explanation

Full Explanation