直接使用一个例子来操作Deployment的伸缩

部署nginx

编写yml文件

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[root@k8s-node1 ~]# vi nginx.yml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 2
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.8
        ports:
        - containerPort: 80

运行nginx-deployment

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[root@k8s-node1 ~]# kubectl apply -f nginx.yml 
deployment.apps/nginx-deployment created

查看运行起来的pod容器

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[root@k8s-node1 ~]# kubectl get pod -o wide
NAME                                READY   STATUS    RESTARTS   AGE     IP           NODE
nginx-deployment-5f8c6846ff-446sl   1/1     Running   0          9m46s   10.244.2.2   k8s-node2
nginx-deployment-5f8c6846ff-4qhvm   1/1     Running   0          9m46s   10.244.1.2   k8s-node3

pod的伸缩

其实也特别简单，就是直接修改yaml文件的replicas配置项的数量

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[root@k8s-node1 ~]# vi nginx.yml
# 修改replicas
  replicas: 5
将pod从2个增加为5个

部署

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[root@k8s-node1 ~]# kubectl apply -f nginx.yml 
deployment.apps/nginx-deployment configured

再次查看

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[root@k8s-node1 ~]# kubectl get pod -o wide
NAME                                READY   STATUS    RESTARTS   AGE   IP           NODE    NOMINATED NODE   READINESS GATES
nginx-deployment-5f8c6846ff-446sl   1/1     Running   0          13m   10.244.2.2   k8s-node2
nginx-deployment-5f8c6846ff-4qhvm   1/1     Running   0          13m   10.244.1.2   k8s-node3
nginx-deployment-5f8c6846ff-5srk7   1/1     Running   0          27s   10.244.1.3   k8s-node3
nginx-deployment-5f8c6846ff-h5cgv   1/1     Running   0          27s   10.244.2.3   k8s-node2
nginx-deployment-5f8c6846ff-stgdn   1/1     Running   0          27s   10.244.2.4   k8s-node2

就这么简单，伸缩已经完成了，不会停掉之前的2个pod，直接在2个的基础上，保证pod总数为5

管理节点参与运算调度

发现所有的pod都运行在node2和node3，k8s中为了管理节点的安全考虑，在分配pod运行主机时，管理节点不参与运算。
如果希望管理节点参与运算执行
kubectl taint node 管理节点主机名 node-role.kubernetes.io/master-
再次恢复管理节点的状态执行
kubectl taint node 管理节点主机名 node-role.kubernetes.io/master="":NoSchedule

重新伸缩，查看管理节点上是否运行pod

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[root@k8s-node1 ~]# vi nginx.yml
# 修改replicas
  replicas: 8

部署

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[root@k8s-node1 ~]# kubectl apply -f nginx.yml 
deployment.apps/nginx-deployment configured

查看pod运行节点

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[root@k8s-node1 ~]# kubectl get pod -o wide
NAME                                READY   STATUS    RESTARTS   AGE   IP           NODE 
nginx-deployment-5f8c6846ff-4qhvm   1/1     Running   0          81m   10.244.1.2   k8s-node3
nginx-deployment-5f8c6846ff-5kk2c   1/1     Running   0          2s    10.244.0.10  k8s-node1
nginx-deployment-5f8c6846ff-8s5mk   1/1     Running   0          2s    10.244.2.37  k8s-node2
nginx-deployment-5f8c6846ff-b9rdj   1/1     Running   0          19s   10.244.2.34  k8s-node2
nginx-deployment-5f8c6846ff-c8dv8   1/1     Running   0          19s   10.244.1.21  k8s-node3
nginx-deployment-5f8c6846ff-fk994   1/1     Running   0          2s    10.244.2.36  k8s-node2
nginx-deployment-5f8c6846ff-g2sqz   1/1     Running   0          19s   10.244.2.33  k8s-node2
nginx-deployment-5f8c6846ff-hks7l   1/1     Running   0          19s   10.244.1.22  k8s-nodee3
nginx-deployment-5f8c6846ff-lhxl4   1/1     Running   0          19s   10.244.2.35  k8s-node2
nginx-deployment-5f8c6846ff-lzct7   1/1     Running   0          2s    10.244.0.11  k8s-node1
nginx-deployment-5f8c6846ff-m5vs9   1/1     Running   0          19s   10.244.1.23  k8s-node3
nginx-deployment-5f8c6846ff-nwbwk   1/1     Running   0          19s   10.244.2.32  k8s-node2
nginx-deployment-5f8c6846ff-rcjlg   1/1     Running   0          19s   10.244.2.31  k8s-node2
nginx-deployment-5f8c6846ff-sfq2d   1/1     Running   0          2s    10.244.1.24  k8s-node3

恢复管理节点的only状态

设置值为NoScheduler，不让调度器进行调度

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[root@k8s-node1 ~]# kubectl taint node node1 node-role.kubernetes.io/master="":NoSchedule
node/node1 tainted

将副本设置为1个

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[root@k8s-node1 ~]# kubectl get pod -o wide
NAME                                READY   STATUS    RESTARTS   AGE    IP           NODE
nginx-deployment-5f8c6846ff-4qhvm   1/1     Running   0          88m    10.244.1.2   k8s-node3

然后再次伸缩为多个pod

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[root@k8s-node1 ~]# kubectl get pod -o wide
NAME                                READY   STATUS    RESTARTS   AGE   IP            NODE 
nginx-deployment-5f8c6846ff-4qhvm   1/1     Running   0          90m   10.244.1.2    k8s-node3 
nginx-deployment-5f8c6846ff-5j87g   1/1     Running   0          3s    10.244.1.26   k8s-node3 
nginx-deployment-5f8c6846ff-6kd6h   1/1     Running   0          3s    10.244.2.38   k8s-node2