What is Kubernetes node affinity?

What is Kubernetes node affinity?

Kubernetes node affinity is a set of rules that allow you to constrain which nodes your pods are eligible to be scheduled on based on labels on the nodes.

How does node affinity differ from node selectors?

Node affinity is more expressive than node selectors. While node selectors allow you to specify exact matches, node affinity supports operators like In, NotIn, Exists, and DoesNotExist.

Can you give me an example of how to use node affinity in a pod specification?

Sure! Here's a simple example:

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
        - matchExpressions:
          - key: disktype
            operator: In
            values:
            - ssd
  containers:
  - name: my-container
    image: my-image

What happens if no nodes match the affinity rules?

If no nodes match the affinity rules, the pod will remain in a pending state until a suitable node becomes available.