Pod的冗余保护

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k8s使用ReplicationController和ReplicaSet对pod进行冗余保护控制，ReplicationController逐渐被淘汰。另外还有DaemonSets，Job，CronJob几种特殊需求的冗余控制，使用配置文件定制好了冗余Pod数量之后，k8s自动进行Pod的冗余监控以及停启操作。

创建RC和RS等的方式与创建Pod等一样，使用指令，

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[root@master ~]# kubectl create -f myweb_replicationset.yaml
replicaset.apps/mywebrs created
[root@master ~]# kubectl get rs
NAME                  DESIRED   CURRENT   READY   AGE
my-nginx-86459cfc9f   2         2         2       59s
mywebrs               3         3         3       8s
[root@master ~]# kubectl get pod
NAME                        READY   STATUS    RESTARTS   AGE
my-nginx-86459cfc9f-48c2s   1/1     Running   0          68s
my-nginx-86459cfc9f-wz6ng   1/1     Running   0          68s
mywebrs-bddcv               1/1     Running   0          17s
mywebrs-jczxq               1/1     Running   0          17s
mywebrs-ksk66               1/1     Running   0          17s

其中myweb_replicationset.yaml文件内容为，

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apiVersion: apps/v1beta2
kind: ReplicaSet
metadata:
    name: mywebrs
spec:
    replicas: 3
    selector:
      matchLabels:
        app: mywebv1
    template:
      metadata:
        labels:
          app: mywebv1
      spec:
        restartPolicy: Always
        containers:
        - name: myweb
          image: mywebv1
          imagePullPolicy: Never
          ports:
          - containerPort: 80
            protocol: TCP

此时删除手动删除Pod，RS会自动创建符合配置文件定义的Pod数量及内容。

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[root@master ~]# kubectl delete pod mywebrs-ksk66
pod "mywebrs-ksk66" deleted

[root@master ~]# kubectl get pod
NAME                        READY   STATUS    RESTARTS   AGE
my-nginx-86459cfc9f-48c2s   1/1     Running   0          8m28s
my-nginx-86459cfc9f-wz6ng   1/1     Running   0          8m28s
mywebrs-bddcv               1/1     Running   0          7m37s
mywebrs-h9hvz               1/1     Running   0          6s
mywebrs-jczxq               1/1     Running   0          7m37s