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>