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: apps/v1
kind: Deployment
metadata:
  name: nginx-test
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      nodeName: 192.168.56.13 # 指定pod调度到该节点
      containers:
      - name: nginx
        image: nginx:latest
        imagePullPolicy: IfNotPresent # 镜像拉取策略
        ports:
        - containerPort: 80

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 <node-name> <label-key>=<label-value>
kubectl label nodes 192.168.56.13 server_type=game_server

确认标记

[root@linux-node1 ~]#  kubectl get nodes 192.168.56.14 --show-labels
NAME            STATUS    ROLES     AGE       VERSION   LABELS
192.168.56.14   Ready     <none>    81d       v1.10.1   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/hostname=192.168.56.14,server_type=game_server
Pod定义中添加nodeSelector
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-test
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:latest
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 80
      nodeSelector: 
        server_type: game_server #指定调度节点为带有label标记为server_type=game_server