cmd/k8s-operator: allow pod tolerations on nameservers (#17260)

This commit modifies the `DNSConfig` custom resource to allow specifying
[tolerations](https://kubernetes.io/docs/concepts/scheduling-eviction/taint-and-toleration/)
on the nameserver pods.

This will allow users to dictate where their nameserver pods are located
within their clusters.

Fixes: https://github.com/tailscale/tailscale/issues/17092

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

k8s-operator/apis/v1alpha1/types_tsdnsconfig.go

@@ -6,6 +6,7 @@
 package v1alpha1
 
 import (
+	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
@@ -84,6 +85,9 @@ type Nameserver struct {
 	// Service configuration.
 	// +optional
 	Service *NameserverService `json:"service,omitempty"`
+	// Pod configuration.
+	// +optional
+	Pod *NameserverPod `json:"pod,omitempty"`
 	// Replicas specifies how many Pods to create. Defaults to 1.
 	// +optional
 	// +kubebuilder:validation:Minimum=0
@@ -105,6 +109,12 @@ type NameserverService struct {
 	ClusterIP string `json:"clusterIP,omitempty"`
 }
 
+type NameserverPod struct {
+	// If specified, applies tolerations to the pods deployed by the DNSConfig resource.
+	// +optional
+	Tolerations []corev1.Toleration `json:"tolerations,omitempty"`
+}
+
 type DNSConfigStatus struct {
 	// +listType=map
 	// +listMapKey=type

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

@@ -422,6 +422,11 @@ func (in *Nameserver) DeepCopyInto(out *Nameserver) {
 		*out = new(NameserverService)
 		**out = **in
 	}
+	if in.Pod != nil {
+		in, out := &in.Pod, &out.Pod
+		*out = new(NameserverPod)
+		(*in).DeepCopyInto(*out)
+	}
 	if in.Replicas != nil {
 		in, out := &in.Replicas, &out.Replicas
 		*out = new(int32)
@@ -454,6 +459,28 @@ func (in *NameserverImage) DeepCopy() *NameserverImage {
 	return out
 }
 
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *NameserverPod) DeepCopyInto(out *NameserverPod) {
+	*out = *in
+	if in.Tolerations != nil {
+		in, out := &in.Tolerations, &out.Tolerations
+		*out = make([]corev1.Toleration, len(*in))
+		for i := range *in {
+			(*in)[i].DeepCopyInto(&(*out)[i])
+		}
+	}
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new NameserverPod.
+func (in *NameserverPod) DeepCopy() *NameserverPod {
+	if in == nil {
+		return nil
+	}
+	out := new(NameserverPod)
+	in.DeepCopyInto(out)
+	return out
+}
+
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in *NameserverService) DeepCopyInto(out *NameserverService) {
 	*out = *in