plugin/kubernetes: support pods with multiple IPs (#8635)

The Pod object stored only the primary pod IP (status.podIP), causing
PodIndex lookups to fail for IPv6 clients in dual-stack clusters. This
prevented the metadata plugin from populating client-pod-name and
client-namespace.

Replace the PodIP string field with a PodIPs []string slice populated
from status.podIPs, and update podIPIndexFunc to index all IPs.

Signed-off-by: Christian Norbert Menges <christian.norbert.menges@sap.com>

plugin/kubernetes/kubernetes.go

@@ -8,6 +8,7 @@ import (
 	"net"
 	"net/http"
 	"runtime"
+	"slices"
 	"strings"
 	"time"
 
@@ -445,7 +446,7 @@ func (k *Kubernetes) findPods(r recordRequest, zone string) (pods []msg.Service,
 
 	for _, p := range k.APIConn.PodIndex(ip) {
 		// check for matching ip and namespace
-		if ip == p.PodIP && match(namespace, p.Namespace) {
+		if slices.Contains(p.PodIPs, ip) && match(namespace, p.Namespace) {
 			s := msg.Service{Key: strings.Join([]string{zonePath, Pod, namespace, podname}, "/"), Host: ip, TTL: k.ttl}
 			pods = append(pods, s)