k8s-operator: add IPv6 support for DNS records (#16691)

This change adds full IPv6 support to the Kubernetes operator's DNS functionality,
enabling dual-stack and IPv6-only cluster support.

Fixes #16633

Signed-off-by: Raj Singh <raj@tailscale.com>

k8s-operator/api.md

@@ -213,7 +213,6 @@ NB: if you want cluster workloads to be able to refer to Tailscale Ingress
 using its MagicDNS name, you must also annotate the Ingress resource with
 tailscale.com/experimental-forward-cluster-traffic-via-ingress annotation to
 ensure that the proxy created for the Ingress listens on its Pod IP address.
-NB: Clusters where Pods get assigned IPv6 addresses only are currently not supported.
 
 
 

k8s-operator/apis/v1alpha1/types_tsdnsconfig.go

@@ -45,7 +45,6 @@ var DNSConfigKind = "DNSConfig"
 // using its MagicDNS name, you must also annotate the Ingress resource with
 // tailscale.com/experimental-forward-cluster-traffic-via-ingress annotation to
 // ensure that the proxy created for the Ingress listens on its Pod IP address.
-// NB: Clusters where Pods get assigned IPv6 addresses only are currently not supported.
 type DNSConfig struct {
 	metav1.TypeMeta   `json:",inline"`
 	metav1.ObjectMeta `json:"metadata,omitempty"`

k8s-operator/utils.go

@@ -27,6 +27,11 @@ type Records struct {
 	Version string `json:"version"`
 	// IP4 contains a mapping of DNS names to IPv4 address(es).
 	IP4 map[string][]string `json:"ip4"`
+	// IP6 contains a mapping of DNS names to IPv6 address(es).
+	// This field is optional and will be omitted from JSON if empty.
+	// It enables dual-stack DNS support in Kubernetes clusters.
+	// +optional
+	IP6 map[string][]string `json:"ip6,omitempty"`
 }
 
 // TailscaledConfigFileName returns a tailscaled config file name in