Add affinity support for DT oneAgent

[a7vicky]

Is your feature request related to a problem? Please describe.

Since oneAgent is daemonset and daemonset supports affinity for pod's scheduling constraints, This would be nice to give users the flexibility to use matchExpressions to schedule pods on the desired nodes.

→ kubectl explain ds.spec.template.spec.affinity --recursive

KIND:     DaemonSet
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>
      preferredDuringSchedulingIgnoredDuringExecution	<[]Object>
         preference	<Object>
            matchExpressions	<[]Object>
               key	<string>
               operator	<string>
               values	<[]string>
            matchFields	<[]Object>
               key	<string>
               operator	<string>
               values	<[]string>
         weight	<integer>
      requiredDuringSchedulingIgnoredDuringExecution	<Object>
         nodeSelectorTerms	<[]Object>
            matchExpressions	<[]Object>
               key	<string>
               operator	<string>
               values	<[]string>
            matchFields	<[]Object>
               key	<string>
               operator	<string>
               values	<[]string>
   podAffinity	<Object>
      preferredDuringSchedulingIgnoredDuringExecution	<[]Object>
         podAffinityTerm	<Object>
            labelSelector	<Object>
               matchExpressions	<[]Object>
                  key	<string>
                  operator	<string>
                  values	<[]string>
               matchLabels	<map[string]string>
            namespaceSelector	<Object>
               matchExpressions	<[]Object>
                  key	<string>
                  operator	<string>
                  values	<[]string>
               matchLabels	<map[string]string>
            namespaces	<[]string>
            topologyKey	<string>
         weight	<integer>
      requiredDuringSchedulingIgnoredDuringExecution	<[]Object>
         labelSelector	<Object>
            matchExpressions	<[]Object>
               key	<string>
               operator	<string>
               values	<[]string>
            matchLabels	<map[string]string>
         namespaceSelector	<Object>
            matchExpressions	<[]Object>
               key	<string>
               operator	<string>
               values	<[]string>
            matchLabels	<map[string]string>
         namespaces	<[]string>
         topologyKey	<string>
   podAntiAffinity	<Object>
      preferredDuringSchedulingIgnoredDuringExecution	<[]Object>
         podAffinityTerm	<Object>
            labelSelector	<Object>
               matchExpressions	<[]Object>
                  key	<string>
                  operator	<string>
                  values	<[]string>
               matchLabels	<map[string]string>
            namespaceSelector	<Object>
               matchExpressions	<[]Object>
                  key	<string>
                  operator	<string>
                  values	<[]string>
               matchLabels	<map[string]string>
            namespaces	<[]string>
            topologyKey	<string>
         weight	<integer>
      requiredDuringSchedulingIgnoredDuringExecution	<[]Object>
         labelSelector	<Object>
            matchExpressions	<[]Object>
               key	<string>
               operator	<string>
               values	<[]string>
            matchLabels	<map[string]string>
         namespaceSelector	<Object>
            matchExpressions	<[]Object>
               key	<string>
               operator	<string>
               values	<[]string>
            matchLabels	<map[string]string>
         namespaces	<[]string>
         topologyKey	<string>

Describe the solution you'd like
Extend dynakube CRD fields to add affinity for oneAgnet daemonset and the dynatrace-operator creates daemonset using these fields.

Describe alternatives you've considered
nodeSelector: This is not a solution in our case because the label we want to use is dynamically added by the controller and the value for that label is not constant.

[mfabricanti]

Up!

I need to monitor only a few nodes of a cluster.
It would be nice to have the hability to use nodeAfinity for OneAgent.