04 - node-affinity.md

Node Affinity

Example with 2 Node Labels:

apiVersion: v1
kind: Pod
metadata:
  name: nginx
  labels:
    name: nginx
spec:
  containers:
  - name: nginx
    image: nginx
    ports:
    - containerPort: 80
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
        - matchExpressions:
          - key: size
            operator: In
            values:
            - Large
            - Medium

• Types:
  • requiredDuringSchedulingIgnoredDuringExecution
    • Node Label is Required
  • preferredDuringSchedulingIgnoredDuringExecution
    • Node Label is not Required, if not found will place it anywhere in the cluster
  • requiredDuringSchedulingRequiredDuringExecution
    • Node Label is Required and if the label is removed, it will remove the POD as well

If you only wanna check if the label exists operator: Exists, example:

• affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
        - matchExpressions:
          - key: size
            operator: Exists            
  

Official Doc.: https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/