plugin/kubernetes: Handle multiple local IPs and bind (#3208)

* use all local IPs

* mult/bind ips

* gofmt + boundIPs fix

* fix no matching endpoint case

* don't duplicate NS records in answer

* fix answer dedup

* fix comment

* add multi local ip test case

plugin/kubernetes/kubernetes.go

@@ -43,11 +43,10 @@ type Kubernetes struct {
 	Fall             fall.F
 	ttl              uint32
 	opts             dnsControlOpts
-
-	primaryZoneIndex   int
-	interfaceAddrsFunc func() net.IP
-	autoPathSearch     []string // Local search path from /etc/resolv.conf. Needed for autopath.
-	TransferTo         []string
+	primaryZoneIndex int
+	localIPs         []net.IP
+	autoPathSearch   []string // Local search path from /etc/resolv.conf. Needed for autopath.
+	TransferTo       []string
 }
 
 // New returns a initialized Kubernetes. It default interfaceAddrFunc to return 127.0.0.1. All other
@@ -56,7 +55,6 @@ func New(zones []string) *Kubernetes {
 	k := new(Kubernetes)
 	k.Zones = zones
 	k.Namespaces = make(map[string]struct{})
-	k.interfaceAddrsFunc = func() net.IP { return net.ParseIP("127.0.0.1") }
 	k.podMode = podModeDisabled
 	k.ttl = defaultTTL