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Note, full “K8s Interview Questions” mind map is available at: “K8s Interview Questions Mind Map”
What is K8s Controller?
K8s utilizes controllers to manage its various tasks and maintain desired states. A controller in K8s is a looped control plane process that watches the shared state of the cluster through the api-server and then makes changes attempting to move the current state towards the desired state.
It uses the observed state, usually derived from the etcd datastore, to continually compare against the desired state and rectify any discrepancies. For instance, consider the Deployment controller: when you request a new deployment, the Deployment controller ensures that the specified number of pod replicas are maintained. If a pod crashes or gets deleted, the Deployment controller automatically replaces it to maintain the desired state.
What is ReplicaSet?
A ReplicaSet is a fundamental resource designed to maintain a stable set of replica pods running at any given time. It ensures that a specified number of identical pod replicas are running and operational. This is particularly beneficial for redundancy and scalability, helping applications to stay available and cope with demands.
