How to properly use controller.affinity annotation?

Question

Does anyone know how to properly use controller.affinity annotation? In the doc we can see only annotation name w/o type or any example. https://docs.nginx.com/nginx-ingress-controller/installation/installation-with-helm/ I was trying to use it as I did for toleration:

--set controller.affinity[0].key=key_here \
--set controller.affinity[0].operator=In \
--set controller.affinity[0].values[0]=value_here

getting validation error expected map instead of array... next few try:

--set controller.affinity[0].key=key_here \
--set controller.affinity[0].operator=In \
--set controller.affinity[0].value=value_here

validation error expected map instead of array

--set controller.affinity.key=key_here \
--set controller.affinity.operator=In \
--set controller.affinity.values=value_here

error validating data: [ValidationError(Deployment.spec.template.spec.affinity): unknown field "key" in io.k8s.api.core.v1.Affinity

Any idea how to properly use it?

For example for controller.tolerations this worked from first try:

--set controller.tolerations[0].key=taint \
--set controller.tolerations[0].value=node_taint_here \
--set controller.tolerations[0].effect=NoSchedule

Answer 1

There is no "key" field in affinity, you can easily check that with

kubectl explain deployment.spec.template.spec.affinity
KIND:     Deployment
VERSION:  apps/v1

RESOURCE: affinity <Object>

DESCRIPTION:
     If specified, the pod's scheduling constraints

     Affinity is a group of affinity scheduling rules.

FIELDS:
   nodeAffinity <Object>
     Describes node affinity scheduling rules for the pod.

   podAffinity  <Object>
     Describes pod affinity scheduling rules (e.g. co-locate this pod in the
     same node, zone, etc. as some other pod(s)).

   podAntiAffinity      <Object>
     Describes pod anti-affinity scheduling rules (e.g. avoid putting this pod
     in the same node, zone, etc. as some other pod(s)).

So if you want to add nodeAffinity, similarly to official docs https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/#node-affinity , you can specify key like this:

--set 'controller.affinity.nodeAffinity.requiredDuringSchedulingIgnoredDuringExecution.nodeSelectorTerms[0].matchExpressions[0].key=topology.kubernetes.io/zone'

As you can see, this can be quite tedious, and generally, you should use or generate values file, like

controller:
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
        - matchExpressions:
          - key: topology.kubernetes.io/zone
            operator: In
            values:
            - antarctica-east1
            - antarctica-west1

and add it with -f instead of adding 4 big arguments