k8s/StudyNotes/NodeSelectors & Node Affinity

Example is different size nodes, with labels Large, Medium, Small
Get labels on node
```
kubectl get nodes node01 --show-labels
```

(Older)nodeSelector, no logic. Ind pod-def.yaml, add to spec: nodeSelector:

apiVersion:
kind: Pod
metadata:
  name: myapp-pod
spec:
  containers:
  - name: data-processor
    image: dataproc
  nodeSelector:
    size: Large

label node with

kubectl label node 

 2. (Newer)Node Affinity and anti affinity. 
   * Node Affinity more flexabe but complex, e.g. pick large node {{{
spec:
  containers:
    ...
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoreDuringExecution:
        nodeSeletorTerms:
        - matchExpressions:
          - key: size
            operator: In
            values:
            - Large

2x types of Node affinity
1. requiredDuringSchedulingIgnoredDuringExecution
2. preferredDuringSchedulingIgnoredDuringExecution
3. future planned
  1. requiredDuringSchedulingRequiredDuringExecution
  2. preferredDuringSchedulingRequiredDuringExecution
Node Affinity, can have different operator's:
- operator: In
- operator: Exists