深入kubernetes调度之NodeSelector

1 NodeName

Pod.spec.nodeName用于强制约束将Pod调度到指定的Node节点上，这里说是“调度”，但其实指定了nodeName的Pod会直接跳过Scheduler的调度逻辑，直接写入PodList列表，该匹配规则是强制匹配。

例子：

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: tomcat-deploy
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: tomcat-app
    spec:
      nodeName: k8s.node1 #指定调度节点为k8s.node1
      containers:
      - name: tomcat
        image: tomcat:8.0
        ports:
        - containerPort: 8080

2 NodeSelector

Pod.spec.nodeSelector是通过kubernetes的label-selector机制进行节点选择，由scheduler调度策略MatchNodeSelector进行label匹配，调度pod到目标节点，该匹配规则是强制约束。启用节点选择器的步骤为：

Node添加label标记

#标记规则：kubectl label nodes =

kubectl label nodes k8s.node1 cloudnil.com/role=dev

#确认标记

root@k8s.master1:~# 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定义中添加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 #指定调度节点为带有label标记为：cloudnil.com/role=dev的node节点
      containers:
      - name: tomcat
        image: tomcat:8.0
        ports:
        - containerPort: 8080

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