How to properly use controller.affinity annotation? - kubernetes-helm

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