本文主要介紹kubernetes調度框架中的NodeName和NodeSelector。

1 NodeName

Pod.spec.nodeName用於強制約束將Pod調度到指定的Node節點上，這裏說是“調度”，但其實指定了nodeName的Pod會直接跳過Scheduler的調度邏輯，直接寫入PodList列表，該匹配規則是強制匹配。

例子：

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: tomcat-deploy
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: tomcat
 
-app
    spec:
      nodeName: k8s.node1 #指定調度節點為k8s.node1
      containers:
      - name: tomcat
        image: tomcat:8.0
        ports:
        - containerPort: 8080

2 NodeSelector

Pod.spec.nodeSelector是通過kubernetes的label-selector機制進行節點選擇，由scheduler調度策略MatchNodeSelector進行label匹配，調度pod到目標節點，該匹配規則是強制約束。啟用節點選擇器的步驟為：

• Node添加label標記

#標記規則：kubectl label nodes <node-name> <label-key>=<label-value>
kubectl label nodes k8s.node1 cloudnil.com/role=dev

#確認標記
[email protected]:~# kubectl get nodes k8s.node1 --show-labels
NAME        STATUS    AGE       LABELS
k8s.node1   Ready     29d       beta.kubernetes.io
 
/arch=amd64,beta.kubernetes.io/os=linux,cloudnil.com/role=dev,kubernetes.io/hostname=k8s.node1

• Pod定義中添加nodeSelector

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: tomcat-deploy
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: tomcat-app
    spec:
      nodeSelector:
        cloudnil.com/role: dev #指定調度節點為帶有label標記為：cloudnil.com/role=dev的node節點
      containers:
      - name: tomcat
        image: tomcat:8.0
        ports:
        - containerPort: 8080

深入kubernetes調度之NodeSelector