Controlling Pods with node affinity

As you can probably tell, taints and tolerations – while much more flexible than node selectors – still leave some use cases unaddressed and in general only allow a filter pattern where you can match on a specific taint using Exists or Equals. There may be more advanced use cases where you want more flexible methods of selecting nodes – and affinities are a feature of Kubernetes that addresses this.

There are two types of affinity:

• Node affinity
• Inter-Pod affinity

Node affinity is a similar concept to node selectors except that it allows for a much more robust set of selection characteristics. Let's look at some example YAML and then pick apart the various pieces:

pod-with-node-affinity.yaml

apiVersion: v1
kind: Pod
metadata:
  name: affinity-test
spec:
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution...