I'm trying to understand how kubernetes works, so I tried to do this operation for my minikube:
~ kubectl delete pod --all -n kube-system
pod "coredns-f9fd979d6-5n4b6" deleted
pod "etcd-minikube" deleted
pod "kube-apiserver-minikube" deleted
pod "kube-controller-manager-minikube" deleted
pod "kube-proxy-879lg" deleted
pod "kube-scheduler-minikube" deleted
It's okay. Pods deleted as wish. But if I do kubectl get pods -n kube-system I will see:
NAME READY STATUS RESTARTS AGE
coredns-f9fd979d6-5d25r 1/1 Running 0 50s
etcd-minikube 1/1 Running 0 50s
kube-apiserver-minikube 1/1 Running 0 50s
kube-controller-manager-minikube 1/1 Running 0 50s
kube-proxy-nlw69 1/1 Running 0 43s
kube-scheduler-minikube 1/1 Running 0 49s
Okay. I thought it's ReplicaSet or DaemonSet:
➜ ~ kubectl get ds -n kube-system
NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE
kube-proxy 1 1 1 1 1 kubernetes.io/os=linux 18m
➜ ~ kubectl get rs -n kube-system
NAME DESIRED CURRENT READY AGE
coredns-f9fd979d6 1 1 1 18m
It is true for coredns and kube-proxy. But what about others (apiserver, etcd, controller and scheduler)? Why are they still alive?
The control plane pods are run as static Pods - static Pods are not managed by the control plane controllers like e.g. DaemonSet and ReplicaSet. Static pods are instead managed by the Kubelet daemon on the local node directly.