StatefulSet

Create file sleep_sts.yaml:

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: sleep
spec:
  serviceName: sleep-service
  replicas: 3
  selector:
    matchLabels:
      app: sleep
  podManagementPolicy: Parallel
  template:
    metadata:
      labels:
        app: sleep
    spec:
      restartPolicy: Always
      containers:
        - image: busybox:1.37.0-glibc
          imagePullPolicy: IfNotPresent
          name: sleep-busybox
          command: ["sh", "-c", "trap exit INT TERM; sleep 1m & wait"]
          resources:
            requests:
              cpu: "1"
              memory: 100Mi
            limits:
              cpu: "1"
              memory: 100Mi

Note

restartPolicy must be Always, the default value
selector must be set and match the labels of template

Apply to the cluster:

$ kubectl create -f sleep_sts.yaml
statefulset.apps/sleep created

Watch events:

$ kubectl get sts sleep -owide -w
NAME    READY   AGE   CONTAINERS      IMAGES
sleep   0/3     0s    sleep-busybox   busybox:1.37.0-glibc
sleep   1/3     2s    sleep-busybox   busybox:1.37.0-glibc
sleep   2/3     2s    sleep-busybox   busybox:1.37.0-glibc
sleep   3/3     2s    sleep-busybox   busybox:1.37.0-glibc
sleep   2/3     62s   sleep-busybox   busybox:1.37.0-glibc
sleep   1/3     62s   sleep-busybox   busybox:1.37.0-glibc
sleep   0/3     62s   sleep-busybox   busybox:1.37.0-glibc
sleep   1/3     63s   sleep-busybox   busybox:1.37.0-glibc
sleep   2/3     63s   sleep-busybox   busybox:1.37.0-glibc
sleep   3/3     63s   sleep-busybox   busybox:1.37.0-glibc

Note the pods exited after 1min and restarted.

If we list the resources when the statefulset was 3/3 ready:

$ kubectl get sts,po -owide
NAME                     READY   AGE   CONTAINERS      IMAGES
statefulset.apps/sleep   3/3     17s   sleep-busybox   busybox:1.37.0-glibc

NAME          READY   STATUS    RESTARTS   AGE   IP               NODE     NOMINATED NODE   READINESS GATES
pod/sleep-0   1/1     Running   0          17s   192.168.135.12   las1     <none>           <none>
pod/sleep-1   1/1     Running   0          17s   192.168.5.217    las2     <none>           <none>
pod/sleep-2   1/1     Running   0          17s   192.168.182.29   las3     <none>           <none>