kubernetes:用label让pod在指定的node上运行(kubernetes1.18.3)

一，为什么要为node指定label?

通常scheduler会把pod调度到所有可用的Node，有的情况下我们希望能把 Pod 部署到指定的 Node，

例如:

有的Node上配备了速度更快的SSD磁盘

有的Node上配备了性能更强的GPU,

这样pod中的应用才能更好的发挥node的硬件优势

 

说明：刘宏缔的架构森林是一个专注架构的博客，地址：https://www.cnblogs.com/architectforest

         对应的源码可以访问这里获取： https://github.com/liuhongdi/

说明：作者:刘宏缔 邮箱: 371125307@qq.com

二，用label让pod在指定的node上运行:

1,查看各个node的label:

[root@kubemaster k8s]# kubectl get nodes --show-labels
NAME         STATUS   ROLES    AGE   VERSION   LABELS
kubemaster   Ready    master   27h   v1.18.3   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=kubemaster,kubernetes.io/os=linux,node-role.kubernetes.io/master=
node1        Ready    <none>   72m   v1.18.3   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=node1,kubernetes.io/os=linux

说明：各node的label都是系统默认的，还没有我们手动添加的 

 

2,给一个node添加label

格式:   

kubectl label nodes <node-name> <label-key>=<label-value>

添加

[root@kubemaster k8s]# kubectl label node kubemaster apptype=web1
node/kubemaster labeled
[root@kubemaster k8s]# kubectl label node node1 apptype=web2
node/node1 labeled

查看效果:

[root@kubemaster k8s]# kubectl get nodes --show-labels
NAME         STATUS   ROLES    AGE   VERSION   LABELS
kubemaster   Ready    master   28h   v1.18.3   apptype=web1beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=kubemaster,kubernetes.io/os=linux,node-role.kubernetes.io/master=
node1        Ready    <none>   75m   v1.18.3   apptype=web2,beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=node1,kubernetes.io/os=linux

3,修改label

[root@kubemaster k8s]# kubectl label node node1 apptype=noweb --overwrite
node/node1 labeled

查看效果:

[root@kubemaster k8s]# kubectl get nodes --show-labels
NAME         STATUS   ROLES    AGE   VERSION   LABELS
kubemaster   Ready    master   28h   v1.18.3   apptype=web1,beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=kubemaster,kubernetes.io/os=linux,node-role.kubernetes.io/master=
node1        Ready    <none>   85m   v1.18.3   apptype=noweb,beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=node1,kubernetes.io/os=linux

4,删除label

#格式：

kubectl label nodes <node-name> <label-key>-

删除

[root@kubemaster k8s]# kubectl label nodes node1 apptype-
node/node1 labeled

三，如何把Pod 部署到指定label的 Node:

在yaml文件中添加:

    spec:段下面

      nodeSelector:
        apptype: web

看一个例子：

[root@kubemaster k8s]# more nginx-rc.yaml
apiVersion: v1
kind: ReplicationController
metadata:
  name: nginx-demo
spec:
  replicas: 2
  selector:
    app: nginx-demo
  template:
    metadata:
      labels:
        app: nginx-demo
    spec:
      nodeSelector:
        apptype: web
      containers:
      - name: nginx-demo
        image: nginx
        ports:
        - containerPort: 80

查看当前node的label

[root@kubemaster k8s]# kubectl get nodes --show-labels
NAME         STATUS   ROLES    AGE    VERSION   LABELS
kubemaster   Ready    master   28h    v1.18.3   apptype=noweb,beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=kubemaster,kubernetes.io/os=linux,node-role.kubernetes.io/master=
node1        Ready    <none>   107m   v1.18.3   apptype=web,beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=node1,kubernetes.io/os=linux

运行:

[root@kubemaster k8s]# kubectl apply -f nginx-rc.yaml
replicationcontroller/nginx-demo created

查看效果:

[root@kubemaster k8s]# kubectl get pods -o wide
NAME               READY   STATUS    RESTARTS   AGE   IP               NODE    NOMINATED NODE   READINESS GATES
nginx-demo-b5vwt   1/1     Running   0          15m   172.16.166.136   node1   <none>           <none>
nginx-demo-j8n7d   1/1     Running   0          15m   172.16.166.135   node1   <none>           <none> 

四，查看kubernetes的版本

[root@kubemaster ~]# kubelet --version
Kubernetes v1.18.3
[root@kubemaster ~]# kubeadm version
kubeadm version: &version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.3", GitCommit:"2e7996e3e2712684bc73f0dec0200d64eec7fe40",
 GitTreeState:"clean", BuildDate:"2020-05-20T12:49:29Z", GoVersion:"go1.13.9", Compiler:"gc", Platform:"linux/amd64”}

五，查看linux的版本

[root@kubemaster ~]# cat /etc/redhat-release
CentOS Linux release 8.2.2004 (Core)
[root@kubemaster ~]# uname -r
4.18.0-193.el8.x86_64