Question - How etcd collects information from worker nodes about their state? How data flows?
kubeletes update the state using the API gateway and then the scheduler does whats needed to get the state into desire state
The Kubernetes API server stores each cluster’s state data in etcd. Kubernetes uses etcd’s “watch” function to monitor this data and to reconfigure itself when changes occur. The “watch” function stores values representing the actual and ideal state of the cluster and can initiate a response when they diverge.
Each Worker Running with Agent named Kubelet provide information about worker nodes(Pods status, node resources etc…) to Master control plane.The control take care of that to store in etcd database.