k8s pod节点标签选择器-nodeSelector

1. 节点标签选择器

• nodeSelector：用于将Pod调度到匹配Label的Node上，如果没有匹配的标签会调度失败。

  • 作用：
    约束Pod到特定的节点运行
    完全匹配节点标签
  • 应用场景：
    专用节点：根据业务线将Node分组管理
    配备特殊硬件：部分Node配有SSD硬盘、GPU

• 示例：

  确保Pod分配到具有SSD硬盘的节点上

  • 第一步：给节点添加标签
    格式：

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

    例如：

    kubectl label nodes k8s-node1 disktype=ssd
    

    验证：

    kubectl get nodes --show-labels
    

  • 第二步：添加nodeSelector字段到Pod配置中

    apiVersion: v1
    kind: Pod
    metadata:
      name: pod-example
    spec:
      nodeSelector:
        disktype: "ssd"
      containers:
      - name: nginx
        image: nginx:1.19
    

  • 最后，验证：

    kubectl get pods -o wide
    

2. nodeSelector案例

• 给k8s-node1标记标签

  [root@k8s-master yaml]# kubectl label nodes k8s-node1 disktype="ssd"
  node/k8s-node1 labeled
  

• 查看验证

  [root@k8s-master yaml]# kubectl get nodes --show-labels 
  NAME         STATUS   ROLES    AGE    VERSION   LABELS
  k8s-master   Ready    master   5d1h   v1.19.0   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-master,kubernetes.io/os=linux,node-role.kubernetes.io/master=
  k8s-node1    Ready    <none>   5d     v1.19.0   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,disktype=ssd,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-node1,kubernetes.io/os=linux
  k8s-node2    Ready    <none>   5d     v1.19.0   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-node2,kubernetes.io/os=linux
  

• 编写配置文件

  [root@k8s-master yaml]# vim pod-example.yaml
  [root@k8s-master yaml]# cat pod-example.yaml 
  apiVersion: v1
  kind: Pod
  metadata:
    name: pod-example
  spec:
    nodeSelector:
      disktype: "ssd"
    containers:
    - name: nginx
      image: nginx:1.19
  

• 运行服务

  [root@k8s-master yaml]# kubectl apply -f pod-example.yaml 
  pod/pod-example created
  

• 验证服务

  [root@k8s-master yaml]# kubectl get pods -o wideNAME          READY   STATUS    RESTARTS   AGE    IP               NODE        NOMINATED NODE   READINESS GATESinit-demo     1/1     Running   0          23h    10.244.36.93     k8s-node1   <none>           <none>pod-envars    1/1     Running   2          24h    10.244.36.91     k8s-node1   <none>           <none>pod-example   1/1     Running   0          107s   10.244.36.94     k8s-node1   <none>           <none>web           1/1     Running   0          130m   10.244.169.158   k8s-node2   <none>           <none>
  

• 注释：

  1. 经过测试，在k8s-node1上已经做好标签，在配置文件写入的时候，会引入标签使用，
  2. 如果在，主机上没有设置标签，就会一直在pending的状态，知道有标签才会分配

3. nodeselector使用deployment来创建

• 查看标签名

  [root@k8s-master yaml]# kubectl get nodes --show-labels NAME         STATUS   ROLES    AGE    VERSION   LABELSk8s-master   Ready    master   5d1h   v1.19.0   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-master,kubernetes.io/os=linux,node-role.kubernetes.io/master=k8s-node1    Ready    <none>   5d     v1.19.0   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,disktype=ssd,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-node1,kubernetes.io/os=linuxk8s-node2    Ready    <none>   5d     v1.19.0   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-node2,kubernetes.io/os=linux
  

• 生成配置文件

  [root@k8s-master pod]# kubectl create deployment web --replicas=1 --image=nginx --dry-run=client -o yaml > kubelet_pod.yaml[root@k8s-master pod]# vim kubelet_pod.yaml [root@k8s-master pod]# cat kubelet_pod.yaml apiVersion: apps/v1kind: Deploymentmetadata:  labels:    app: web  name: webspec:  replicas: 1  selector:    matchLabels:      app: web  strategy: {}  template:    metadata:      labels:        app: web    spec:      nodeSelector:        kubernetes.io/hostname: "k8s-node01"      containers:      - image: nginx        name: nginx
  

• 启动配置文件

  [root@k8s-master pod]# kubectl apply -f kubelet_pod.yaml deployment.apps/web unchanged
  

• 验证是否在node01节点

  [root@k8s-master pod]# kubectl get pods -o wideNAME                  READY   STATUS    RESTARTS   AGE     IP              NODE         NOMINATED NODE   READINESS GATESweb-6b8c6845f-b4l2m   1/1     Running   0          4m12s   10.244.85.212   k8s-node01   <none>           <none>