Kubernetes node affinity

Node affinity is a generalization of the node selector method, which allows the necessary rules and preference rules to be specified

The following example is an nginx, which is required by affinity rules

Only nodes with more than 3 cores (excluding 3) are considered

Try to select nodes that are not master nodes

There is also a weight with a value of 1. If this node matches the name and is not master, it will get a weight score of 1

Finally, the scheduler will select a node with the highest weight score, and the weight is a list

Look at the following example

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-hello-deployment
  namespace: lizhe
  labels:
    app: nginx-hello
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx-hello
  template:
    metadata:
      labels:
        app: nginx-hello
    spec:
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: numberCores
                operator: Gt
                values: ["3"]
          preferredDuringSchedulingIgnoredDuringExecution:
          - weight: 1
            preference:
              matchFields:
              - key: metadata.name
                operator: NotIn
                values: ["master"]
      containers:
      - name: nginx-hello
        image: nginx
        ports:
        - containerPort: 80

In this example, numbercores is used. Please don’t mistakenly think that this is a native field. In fact, this is a label on node, which we need to create manually

If it is not created, the scheduling will not succeed

add label

now it can be scheduled