1. 節點標籤選擇器

• nodeSelector：用於將Pod排程到匹配Label的Node上，如果沒有匹配的標籤會排程失敗。

  • 作用：
    約束Pod到特定的節點執行
    完全匹配節點標籤
  • 應用場景：
    專用節點：根據業務線將Node分組管理
    配備特殊硬體：部分Node配有SSD硬碟、GPU

• 示例：

  確保Pod分配到具有SSD硬碟的節點上

  • 第一步：給節點新增標籤
    格式：

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

    例如：

    kubectl label nodes k8s-node1 disktype=ssd
     
    

    驗證：

    kubectl get nodes --show-labels
    

  • 第二步：新增nodeSelector欄位到Pod配置中

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

  • 最後，驗證：

    kubectl get pods -o wide
    

2. nodeSelector案例

• 給k8s-node1標記標籤

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

• 檢視驗證

  [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
   
  

• 編寫配置檔案

  [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
  

• 執行服務

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

• 驗證服務

  [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>
  

• 註釋：

  1. 經過測試，在k8s-node1上已經做好標籤，在配置檔案寫入的時候，會引入標籤使用，
  2. 如果在，主機上沒有設定標籤，就會一直在pending的狀態，知道有標籤才會分配

3. nodeselector使用deployment來建立

• 檢視標籤名

  [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
  

• 生成配置檔案

  [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
  

• 啟動配置檔案

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

• 驗證是否在node01節點

  [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>