k8s基础篇 pod(六)节点选择器

6.node节点选择器

我们在创建pod资源的时候，pod会根据schduler进行调度，那么默认会调度到随机的一个工作节点，如果我们想要pod调度到指定节点或者调度到一些具有相同特点的node节点，怎么办呢？ 可以使用pod中的nodeName或者nodeSelector字段指定要调度到的node节点

1、nodeName

指定pod节点运行在哪个具体node上

由于只开了一主一从，需要先k8s01的污点去掉
kubectl taint nodes k8s01 node-role.kubernetes.io/master-

[root@k8s01 ~]# cat pod-node.yaml
apiVersion: v1
kind: Pod
metadata:
  name: demo-pod
  namespace: default
  labels:
    app: myapp
    env: env
spec:
  nodeName: k8s01
  containers:
  - name: tomcat-pod-java
    ports:
    - containerPort: 8080
    image: tomcat:8.5-jre8-alpine
    imagePullPolicy: IfNotPresent
  - name: busybox
    image: busybox:1.28
    imagePullPolicy: IfNotPresent
    command:
    - "/bin/sh"
    - "-c"
    - "sleep 3600"
  
 kubectl apply -f pod-node.yaml
 [root@k8s01 ~]# kubectl get pods -o wide
NAME       READY   STATUS    RESTARTS   AGE   IP             NODE    NOMINATED NODE   READINESS GATES
demo-pod   2/2     Running   0          13s   10.244.73.67   k8s01   <none>           <none>

2、nodeSelector

指定pod调度到具有哪些标签的node节点上 #给node节点打标签，打个具有disk=ceph的标签

kubectl label node k8s02 disk=ceph
[root@k8s01 ~]# kubectl get nodes --show-labels
NAME    STATUS   ROLES                  AGE   VERSION   LABELS
k8s01   Ready    control-plane,master   24h   v1.20.6   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s01,kubernetes.io/os=linux,node-role.kubernetes.io/control-plane=,node-role.kubernetes.io/master=
k8s02   Ready    worker                 24h   v1.20.6   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,disk=ceph,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s02,kubernetes.io/os=linux,node-role.kubernetes.io/worker=worker

[root@k8s01 ~]# cat pod-1.yaml
apiVersion: v1
kind: Pod
metadata:
  name: demo-pod-1
  namespace: default
  labels:
    app: myapp
    env: dev
spec:
  nodeSelector:
    disk: ceph
  containers:
  - name: tomcat-pod-java
    ports:
    - containerPort: 8080
    image: tomcat:8.5-jre8-alpine
    imagePullPolicy: IfNotPresent

kubectl apply -f pod-1.yaml
#查看pod调度到哪个节点
[root@k8s01 ~]# kubectl get pods -o wide
NAME         READY   STATUS    RESTARTS   AGE     IP               NODE    NOMINATED NODE   READIN                                                          ESS GATES
demo-pod     2/2     Running   0          7m46s   10.244.73.67     k8s01   <none>           <none>
demo-pod-1   1/1     Running   0          19s     10.244.236.145   k8s02   <none>           <none>