cmd/k8s-operator: add affinity rules to DNSConfig (#19360)

This commit modifies the `DNSConfig` custom resource to allow the
user to specify affinity rules on the nameserver pods.

Updates: https://github.com/tailscale/tailscale/issues/18556

Signed-off-by: David Bond <davidsbond93@gmail.com>

k8s-operator/api.md

@@ -483,6 +483,7 @@ _Appears in:_
 | Field | Description | Default | Validation |
 | --- | --- | --- | --- |
 | `tolerations` _[Toleration](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.3/#toleration-v1-core) array_ | If specified, applies tolerations to the pods deployed by the DNSConfig resource. |  |  |
+| `affinity` _[Affinity](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.3/#affinity-v1-core)_ | If specified, applies affinity rules to the pods deployed by the DNSConfig resource. |  |  |
 
 
 #### NameserverService

k8s-operator/apis/v1alpha1/types_tsdnsconfig.go

@@ -113,6 +113,9 @@ type NameserverPod struct {
 	// If specified, applies tolerations to the pods deployed by the DNSConfig resource.
 	// +optional
 	Tolerations []corev1.Toleration `json:"tolerations,omitempty"`
+	// If specified, applies affinity rules to the pods deployed by the DNSConfig resource.
+	// +optional
+	Affinity *corev1.Affinity `json:"affinity,omitzero"`
 }
 
 type DNSConfigStatus struct {

k8s-operator/apis/v1alpha1/zz_generated.deepcopy.go

@@ -469,6 +469,11 @@ func (in *NameserverPod) DeepCopyInto(out *NameserverPod) {
 			(*in)[i].DeepCopyInto(&(*out)[i])
 		}
 	}
+	if in.Affinity != nil {
+		in, out := &in.Affinity, &out.Affinity
+		*out = new(corev1.Affinity)
+		(*in).DeepCopyInto(*out)
+	}
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new NameserverPod.