Mastering Kubernetes - Second Edition

Intra-pod communication (container to container)

A running pod is always scheduled on one (physical or virtual) node. That means that all the containers run on the same node and can talk to each other in various ways, such as the local filesystem, any IPC mechanism, or using localhost and well-known ports. There is no danger of port collision between different pods because each pod has its own IP address, and when a container in the pod uses localhost, it applies to the pod's IP address only. So, if container 1 in pod 1 connects to port 1234, which container 2 listens to on pod 1, it will not conflict with another container in pod 2 running on the same node that also listens on port 1234. The only caveat is that if you're exposing ports to ...