現(xiàn)在，再去了解一個新的定義方式。
了解之前，先將剛剛的 pod 刪除

[root@kube-node01 yaml]$ kubectl delete -f rc_nginx.yml
replicationcontroller "nginx" deleted

[root@kube-node01 yaml]$ kubectl get pods
NAME          READY     STATUS        RESTARTS   AGE
nginx-99nns   0/1       Terminating   0          6m
nginx-c5nk4   0/1       Terminating   0          49m
nginx-fjnrn   0/1       Terminating   0          6m
nginx-r2zcm   0/1       Terminating   0          49m

[root@kube-node01 yaml]$ kubectl get pods
NAME          READY     STATUS        RESTARTS   AGE
nginx-fjnrn   0/1       Terminating   0          6m

[root@kube-node01 yaml]$ kubectl get pods
No resources found.

可以看到 pod 會慢慢的消失掉，有點淡入淡出的那種感覺哈。

那么新的定義類型叫做ReplicaSet。

其實這個定義方式與上邊介紹的ReplicationController非常像，官網(wǎng)這樣介紹：

ReplicaSet 是下一代復制控制器?，F(xiàn)在 ReplicaSet 和 Replication Controller 之間的唯一區(qū)別是選擇器支持。ReplicaSet 支持標簽用戶指南中描述的新的基于集合的選擇器要求， 而 Replication Controller 僅支持基于等同的選擇器要求。

同樣是定義一個 yaml 文件，如下：

[root@kube-node01 yaml]$ cat rs_nginx.yml
apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: nginx
  labels:
    tier: frontend
spec:
  replicas: 3
  selector:
    matchLabels:
      tier: frontend
  template:
    metadata:
      name: nginx
      labels:
        tier: frontend
    spec:
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80

創(chuàng)建 pod:

[root@kube-node01 yaml]$ kubectl create -f rs_nginx.yml
replicaset.apps "nginx" created

[root@kube-node01 yaml]$ kubectl get pods
NAME          READY     STATUS              RESTARTS   AGE
nginx-4vp95   1/1       Running             0          8s
nginx-9xxp6   0/1       ContainerCreating   0          8s
nginx-f8vfg   1/1       Running             0          8s

[root@kube-node01 yaml]$ kubectl get rs
NAME      DESIRED   CURRENT   READY     AGE
nginx     3         3         1         4s

關于擴展等，與上邊的一樣

[root@kube-node01 yaml]$ kubectl scale rs nginx --replicas=2
replicaset.extensions "nginx" scaled

[root@kube-node01 yaml]$ kubectl get pods
NAME          READY     STATUS        RESTARTS   AGE
nginx-4vp95   1/1       Running       0          1m
nginx-9xxp6   0/1       Terminating   0          1m
nginx-f8vfg   1/1       Running       0          1m

[root@kube-node01 yaml]$ kubectl get rs
NAME      DESIRED   CURRENT   READY     AGE
nginx     2         2         2         1m
 
[root@kube-node01 yaml]$ kubectl scale rs nginx --replicas=5
replicaset.extensions "nginx" scaled

[root@kube-node01 yaml]$ kubectl get pods
NAME          READY     STATUS              RESTARTS   AGE
nginx-4vp95   1/1       Running             0          2m
nginx-bbxpk   0/1       ContainerCreating   0          2s
nginx-cg8ts   0/1       ContainerCreating   0          2s
nginx-f8vfg   1/1       Running             0          2m
nginx-sgvpd   0/1       ContainerCreating   0          2s

[root@kube-node01 yaml]$ kubectl get rs
NAME      DESIRED   CURRENT   READY     AGE
nginx     5         5         3         2m

[root@kube-node01 yaml]$ kubectl get rs
NAME      DESIRED   CURRENT   READY     AGE
nginx     5         5         4         2m

[root@master replicas-set]$kubectl get rs
NAME      DESIRED   CURRENT   READY     AGE
nginx     5         5         5         2m

這個知識點就到這里，可以根據(jù)以上的一些小實踐，理解其工作方式