Hands-On Microservices with Kubernetes

Secure communication

Kubernetes utilizes client-side certificates to fully authenticate both sides of any external communication (for example, kubectl). All communication to the Kubernetes API from outside should be over HTTP. Internal cluster communication between the API server and the kubelet on the node is over HTTPS too (the kubelet endpoint). But, it doesn't use a client certificate by default (you can enable it).

Communication between the API server and nodes, pods, and services is, by default, over HTTP and is not authenticated. You can upgrade them to HTTPS, but note that the client certificate is checked, so don't run your worker nodes on public networks.