Kubernetes基础：资源扩缩容方法(Replica Set)

「爱情、让人受尽委屈。」 2023-07-03 12:19 5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RS（Replica Set）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

# RS示例说明 #

示例YAML文件如下所示：

[root@host131 ReplicaSet]# cat selecotr-busybox-rs.yaml 
    ---
    apiVersion: apps/v1
    kind: ReplicaSet
    metadata:
      name: test-rs
    spec:
      replicas: 1
      selector:
        matchLabels:
          app: busybox-rs-prod
      template:
        metadata:
          name: busybox
          labels:
            app: busybox-rs-prod
        spec:
          containers:
          - name: busybox-host
            image: busybox:latest
            command: ["sleep"]
            args: ["10000"]
    ...
    [root@host131 ReplicaSet]#

生成RS和Pod

[root@host131 ReplicaSet]# kubectl create -f selecotr-busybox-rs.yaml 
    replicaset.apps/test-rs created
    [root@host131 ReplicaSet]# 
    [root@host131 ReplicaSet]# kubectl get rs -o wide
    NAME      DESIRED   CURRENT   READY   AGE   CONTAINERS     IMAGES           SELECTOR
    test-rs   1         1         1       7s    busybox-host   busybox:latest   app=busybox-rs-prod
    [root@host131 ReplicaSet]# 
    [root@host131 ReplicaSet]# kubectl get pods -o wide
    NAME            READY   STATUS    RESTARTS   AGE   IP             NODE              NOMINATED NODE   READINESS GATES
    test-rs-nrjhh   1/1     Running   0          16s   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 rs/test-rs --replicas=3
    replicaset.apps/test-rs scaled
    [root@host131 ReplicaSet]#

也可以使用如下格式执行操作

[root@host131 ReplicaSet]# kubectl scale rs test-rs --replicas=3
    replicaset.apps/test-rs 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-rs-97thq   0/1     ContainerCreating   0          5s    <none>         192.168.163.131   <none>           <none>
    test-rs-gw72x   0/1     ContainerCreating   0          5s    <none>         192.168.163.131   <none>           <none>
    test-rs-nrjhh   1/1     Running             0          53s   10.254.152.5   192.168.163.131   <none>           <none>
    [root@host131 ReplicaSet]# kubectl get rs -o wide
    NAME      DESIRED   CURRENT   READY   AGE   CONTAINERS     IMAGES           SELECTOR
    test-rs   3         3         3       57s   busybox-host   busybox:latest   app=busybox-rs-prod
    [root@host131 ReplicaSet]# kubectl get pods -o wide
    NAME            READY   STATUS    RESTARTS   AGE   IP             NODE              NOMINATED NODE   READINESS GATES
    test-rs-97thq   1/1     Running   0          14s   10.254.152.7   192.168.163.131   <none>           <none>
    test-rs-gw72x   1/1     Running   0          14s   10.254.152.6   192.168.163.131   <none>           <none>
    test-rs-nrjhh   1/1     Running   0          62s   10.254.152.5   192.168.163.131   <none>           <none>
    [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 rs -o wide
    NAME      DESIRED   CURRENT   READY   AGE     CONTAINERS     IMAGES           SELECTOR
    test-rs   2         2         2       2m36s   busybox-host   busybox:latest   app=busybox-rs-prod
    [root@host131 ReplicaSet]# 
    [root@host131 ReplicaSet]# kubectl get pods -o wide
    NAME            READY   STATUS        RESTARTS   AGE     IP             NODE              NOMINATED NODE   READINESS GATES
    test-rs-97thq   1/1     Running       0          117s    10.254.152.7   192.168.163.131   <none>           <none>
    test-rs-gw72x   1/1     Terminating   0          117s    10.254.152.6   192.168.163.131   <none>           <none>
    test-rs-nrjhh   1/1     Running       0          2m45s   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-rs-97thq   1/1     Running   0          4m1s    10.254.152.7   192.168.163.131   <none>           <none>
    test-rs-nrjhh   1/1     Running   0          4m49s   10.254.152.5   192.168.163.131   <none>           <none>
    [root@host131 ReplicaSet]#