Kubernetes基础：资源扩缩容方法(Replication Controller)

川长思鸟来 2023-07-03 12:17 39阅读 0赞

Kubernetes提供了多种方式对于资源的扩缩容进行操作，这篇文章以RC（Replication Controller）为例进行说明。

# 常用方法 #

## 方法1: 使用kubectl scale进行扩缩容 ##

执行kubectl scale指定资源进行扩缩容操作

> 扩缩容命令：kubectl scale

## 方法2: 修改YAML文件执行kubectl apply进行扩缩容 ##

通过如下步骤进行扩缩容：

*  步骤1: 修改YAML文件的replica的实例数量
 *  步骤2: 通过kubectl apply -f 命令执行扩缩容

# RC示例说明 #

示例YAML文件如下所示：

[root@host131 ReplicaSet]# cat selecotr-busybox-rc.yaml 
    ---
    apiVersion: v1
    kind: ReplicationController
    metadata:
      name: test-rc
    spec:
      replicas: 1
      selector:
        app: busybox-prod
      template:
        metadata:
          name: busybox
          labels:
            app: busybox-prod
        spec:
          containers:
          - name: busybox-host
            image: busybox:latest
            command: ["sleep"]
            args: ["1000"]
    ...
    [root@host131 ReplicaSet]#

生成RC和Pod

[root@host131 ReplicaSet]# kubectl create -f selecotr-busybox-rc.yaml 
    replicationcontroller/test-rc created
    [root@host131 ReplicaSet]# 
    [root@host131 ReplicaSet]# kubectl get rc -o wide
    NAME      DESIRED   CURRENT   READY   AGE   CONTAINERS     IMAGES           SELECTOR
    test-rc   1         1         1       8s    busybox-host   busybox:latest   app=busybox-prod
    [root@host131 ReplicaSet]# 
    [root@host131 ReplicaSet]# kubectl get pods -o wide
    NAME            READY   STATUS    RESTARTS   AGE   IP             NODE              NOMINATED NODE   READINESS GATES
    test-rc-zfhj7   1/1     Running   0          15s   10.254.152.5   192.168.163.131   <none>           <none>
    [root@host131 ReplicaSet]#

*  使用kubectl scale将Pod从1调整为3

[root@host131 ReplicaSet]# kubectl scale rc/test-rc --replicas=3
    replicationcontroller/test-rc scaled
    [root@host131 ReplicaSet]#

也可以使用如下格式执行操作

[root@host131 ReplicaSet]# kubectl scale rc test-rc --replicas=3
    replicationcontroller/test-rc scaled
    [root@host131 ReplicaSet]#

执行结果确认

[root@host131 ReplicaSet]# kubectl get pods -o wide
    NAME            READY   STATUS              RESTARTS   AGE   IP             NODE              NOMINATED NODE   READINESS GATES
    test-rc-6dpmh   0/1     ContainerCreating   0          4s    <none>         192.168.163.131   <none>           <none>
    test-rc-gp8fc   0/1     ContainerCreating   0          4s    <none>         192.168.163.131   <none>           <none>
    test-rc-zfhj7   1/1     Running             0          85s   10.254.152.5   192.168.163.131   <none>           <none>
    [root@host131 ReplicaSet]# 
    [root@host131 ReplicaSet]# kubectl get pods -o wide
    NAME            READY   STATUS    RESTARTS   AGE   IP             NODE              NOMINATED NODE   READINESS GATES
    test-rc-6dpmh   1/1     Running   0          10s   10.254.152.6   192.168.163.131   <none>           <none>
    test-rc-gp8fc   1/1     Running   0          10s   10.254.152.7   192.168.163.131   <none>           <none>
    test-rc-zfhj7   1/1     Running   0          91s   10.254.152.5   192.168.163.131   <none>           <none>
    [root@host131 ReplicaSet]# kubectl get rc -o wide
    NAME      DESIRED   CURRENT   READY   AGE   CONTAINERS     IMAGES           SELECTOR
    test-rc   3         3         3       98s   busybox-host   busybox:latest   app=busybox-prod
    [root@host131 ReplicaSet]#

*  使用kubectl apply方式将Pod从3调整为2

[root@host131 ReplicaSet]# vi selecotr-busybox-rc.yaml 
    [root@host131 ReplicaSet]# grep replicas selecotr-busybox-rc.yaml 
      replicas: 2
    [root@host131 ReplicaSet]# 
    [root@host131 ReplicaSet]# kubectl apply -f selecotr-busybox-rc.yaml 
    Warning: kubectl apply should be used on resource created by either kubectl create --save-config or kubectl apply
    replicationcontroller/test-rc configured
    [root@host131 ReplicaSet]#

确认结果如下所示

[root@host131 ReplicaSet]# kubectl get pods -o wide
    NAME            READY   STATUS        RESTARTS   AGE     IP             NODE              NOMINATED NODE   READINESS GATES
    test-rc-6dpmh   1/1     Terminating   0          2m      10.254.152.6   192.168.163.131   <none>           <none>
    test-rc-gp8fc   1/1     Running       0          2m      10.254.152.7   192.168.163.131   <none>           <none>
    test-rc-zfhj7   1/1     Running       0          3m21s   10.254.152.5   192.168.163.131   <none>           <none>
    [root@host131 ReplicaSet]# kubectl get rc -o wide
    NAME      DESIRED   CURRENT   READY   AGE     CONTAINERS     IMAGES           SELECTOR
    test-rc   2         2         2       3m28s   busybox-host   busybox:latest   app=busybox-prod
    [root@host131 ReplicaSet]# 
    [root@host131 ReplicaSet]# kubectl get pods -o wide
    NAME            READY   STATUS        RESTARTS   AGE     IP             NODE              NOMINATED NODE   READINESS GATES
    test-rc-6dpmh   1/1     Terminating   0          2m13s   10.254.152.6   192.168.163.131   <none>           <none>
    test-rc-gp8fc   1/1     Running       0          2m13s   10.254.152.7   192.168.163.131   <none>           <none>
    test-rc-zfhj7   1/1     Running       0          3m34s   10.254.152.5   192.168.163.131   <none>           <none>
    [root@host131 ReplicaSet]# 
    [root@host131 ReplicaSet]# kubectl get pods -o wide
    NAME            READY   STATUS    RESTARTS   AGE     IP             NODE              NOMINATED NODE   READINESS GATES
    test-rc-gp8fc   1/1     Running   0          6m28s   10.254.152.7   192.168.163.131   <none>           <none>
    test-rc-zfhj7   1/1     Running   0          7m49s   10.254.152.5   192.168.163.131   <none>           <none>
    [root@host131 ReplicaSet]#