Session Manager provides a secure session between a control-plane cluster and worker-plane clusters. It is only useful in a multi-cluster setup where the control-plane and the worker-plane run separately.
The established secure sessions are used for multiple purposes. For example, a end user can access a Jupyter Notebook running in a worker cluster via a secure session. Secure sessions are also used to build a federated k8s cluster.
One unique feature of this secure session is that we don't need to
open any incoming port in a worker-plane cluster. A worker-plane
cluster can be in a private network that is not accessible from
outside. session-manager-agent initializes an outgoing connection to
session-manager-server to establish the session.
