Handle K8s middleware NS record (#662)

* commit for testing in cluster

* commit for testing in cluster

* refactor and add ns.dns record

* Release 007

* reduce heap allocations

* gofmt

* revert accidental Makefile commits

* restore prior rcode for disabled pod mode

* revert Makefile deltas

* add unit tests

* more unit tests

* make isRequestInReverseRange easier to test

* more unit tests

* addressing review feedback

* commit setup.go

1 files changed, 76 insertions, 65 deletions

diff --git a/middleware/kubernetes/kubernetes.go b/middleware/kubernetes/kubernetes.go
index 01e0c9115..5b7b7bc3c 100644
--- a/middleware/kubernetes/kubernetes.go
+++ b/middleware/kubernetes/kubernetes.go
@@ -28,22 +28,23 @@ import (
 
 // Kubernetes implements a middleware that connects to a Kubernetes cluster.
 type Kubernetes struct {
-	Next          middleware.Handler
-	Zones         []string
-	primaryZone   int
-	Proxy         proxy.Proxy // Proxy for looking up names during the resolution process
-	APIEndpoint   string
-	APICertAuth   string
-	APIClientCert string
-	APIClientKey  string
-	APIConn       *dnsController
-	ResyncPeriod  time.Duration
-	Namespaces    []string
-	LabelSelector *unversionedapi.LabelSelector
-	Selector      *labels.Selector
-	PodMode       string
-	ReverseCidrs  []net.IPNet
-	Fallthrough   bool
+	Next           middleware.Handler
+	Zones          []string
+	primaryZone    int
+	Proxy          proxy.Proxy // Proxy for looking up names during the resolution process
+	APIEndpoint    string
+	APICertAuth    string
+	APIClientCert  string
+	APIClientKey   string
+	APIConn        dnsController
+	ResyncPeriod   time.Duration
+	Namespaces     []string
+	LabelSelector  *unversionedapi.LabelSelector
+	Selector       *labels.Selector
+	PodMode        string
+	ReverseCidrs   []net.IPNet
+	Fallthrough    bool
+	interfaceAddrs InterfaceAddrser
 }
 
 const (
@@ -83,36 +84,49 @@ type recordRequest struct {
 var errNoItems = errors.New("no items found")
 var errNsNotExposed = errors.New("namespace is not exposed")
 var errInvalidRequest = errors.New("invalid query name")
+var errZoneNotFound = errors.New("zone not found")
+var errApiBadPodType = errors.New("expected type *api.Pod")
+var errPodsDisabled = errors.New("pod records disabled")
 
 // Services implements the ServiceBackend interface.
-func (k *Kubernetes) Services(state request.Request, exact bool, opt middleware.Options) ([]msg.Service, []msg.Service, error) {
+func (k *Kubernetes) Services(state request.Request, exact bool, opt middleware.Options) (svcs []msg.Service, debug []msg.Service, err error) {
 
-	r, e := k.parseRequest(state.Name(), state.Type())
+	r, e := k.parseRequest(state.Name(), state.QType())
 	if e != nil {
 		return nil, nil, e
 	}
 
 	switch state.Type() {
 	case "A", "SRV":
+		if state.Type() == "A" && isDefaultNS(state.Name(), r) {
+			// If this is an A request for "ns.dns", respond with a "fake" record for coredns.
+			// SOA records always use this hardcoded name
+			svcs = append(svcs, k.defaultNSMsg(r))
+			return svcs, nil, nil
+		}
 		s, e := k.Records(r)
 		return s, nil, e // Haven't implemented debug queries yet.
 	case "TXT":
-		s, e := k.recordsForTXT(r)
-		return s, nil, e
+		err := k.recordsForTXT(r, &svcs)
+		return svcs, nil, err
+	case "NS":
+		err = k.recordsForNS(r, &svcs)
+		return svcs, nil, err
 	}
 	return nil, nil, nil
 }
 
-func (k *Kubernetes) recordsForTXT(r recordRequest) ([]msg.Service, error) {
+func (k *Kubernetes) recordsForTXT(r recordRequest, svcs *[]msg.Service) (err error) {
 	switch r.typeName {
 	case "dns-version":
 		s := msg.Service{
 			Text: DNSSchemaVersion,
 			TTL:  28800,
-			Key:  msg.Path(r.typeName+"."+r.zone, "coredns")}
-		return []msg.Service{s}, nil
+			Key:  msg.Path(strings.Join([]string{r.typeName, r.zone}, "."), "coredns")}
+		*svcs = append(*svcs, s)
+		return nil
 	}
-	return nil, nil
+	return nil
 }
 
 // PrimaryZone will return the first non-reverse zone being handled by this middleware
@@ -122,6 +136,7 @@ func (k *Kubernetes) PrimaryZone() string {
 
 // Reverse implements the ServiceBackend interface.
 func (k *Kubernetes) Reverse(state request.Request, exact bool, opt middleware.Options) ([]msg.Service, []msg.Service, error) {
+
 	ip := dnsutil.ExtractAddressFromReverse(state.Name())
 	if ip == "" {
 		return nil, nil, nil
@@ -131,8 +146,8 @@ func (k *Kubernetes) Reverse(state request.Request, exact bool, opt middleware.O
 	return records, nil, nil
 }
 
-func (k *Kubernetes) isRequestInReverseRange(state request.Request) bool {
-	ip := dnsutil.ExtractAddressFromReverse(state.Name())
+func (k *Kubernetes) isRequestInReverseRange(name string) bool {
+	ip := dnsutil.ExtractAddressFromReverse(name)
 	for _, c := range k.ReverseCidrs {
 		if c.Contains(net.ParseIP(ip)) {
 			return true
@@ -186,7 +201,8 @@ func (k *Kubernetes) getClientConfig() (*rest.Config, error) {
 }
 
 // InitKubeCache initializes a new Kubernetes cache.
-func (k *Kubernetes) InitKubeCache() error {
+
+func (k *Kubernetes) InitKubeCache() (err error) {
 
 	config, err := k.getClientConfig()
 	if err != nil {
@@ -216,12 +232,11 @@ func (k *Kubernetes) InitKubeCache() error {
 	return err
 }
 
-func (k *Kubernetes) parseRequest(lowerCasedName, qtype string) (r recordRequest, err error) {
+func (k *Kubernetes) parseRequest(lowerCasedName string, qtype uint16) (r recordRequest, err error) {
 	// 3 Possible cases
 	//   SRV Request: _port._protocol.service.namespace.type.zone
 	//   A Request (endpoint): endpoint.service.namespace.type.zone
 	//   A Request (service): service.namespace.type.zone
-
 	// separate zone from rest of lowerCasedName
 	var segs []string
 	for _, z := range k.Zones {
@@ -234,11 +249,19 @@ func (k *Kubernetes) parseRequest(lowerCasedName, qtype string) (r recordRequest
 		}
 	}
 	if r.zone == "" {
-		return r, errors.New("zone not found")
+		return r, errZoneNotFound
+	}
+
+	if qtype == dns.TypeNS {
+		return r, nil
+	}
+
+	if qtype == dns.TypeA && isDefaultNS(lowerCasedName, r) {
+		return r, nil
 	}
 
 	offset := 0
-	if qtype == "SRV" {
+	if qtype == dns.TypeSRV {
 		if len(segs) != 5 {
 			return r, errInvalidRequest
 		}
@@ -268,7 +291,7 @@ func (k *Kubernetes) parseRequest(lowerCasedName, qtype string) (r recordRequest
 		}
 		offset = 2
 	}
-	if qtype == "A" && len(segs) == 4 {
+	if qtype == dns.TypeA && len(segs) == 4 {
 		// This is an endpoint A record request. Get first element as endpoint.
 		r.endpoint = segs[0]
 		offset = 1
@@ -282,7 +305,7 @@ func (k *Kubernetes) parseRequest(lowerCasedName, qtype string) (r recordRequest
 		return r, nil
 	}
 
-	if len(segs) == 1 && qtype == "TXT" {
+	if len(segs) == 1 && qtype == dns.TypeTXT {
 		r.typeName = segs[0]
 		return r, nil
 	}
@@ -328,37 +351,35 @@ func endpointHostname(addr api.EndpointAddress) string {
 	return ""
 }
 
-func (k *Kubernetes) getRecordsForK8sItems(services []service, pods []pod, zone string) []msg.Service {
-	var records []msg.Service
+func (k *Kubernetes) getRecordsForK8sItems(services []service, pods []pod, zone string) (records []msg.Service) {
+	zonePath := msg.Path(zone, "coredns")
 
 	for _, svc := range services {
-
-		key := svc.name + "." + svc.namespace + ".svc." + zone
-
 		if svc.addr == api.ClusterIPNone {
 			// This is a headless service, create records for each endpoint
 			for _, ep := range svc.endpoints {
-				ephostname := endpointHostname(ep.addr)
 				s := msg.Service{
-					Key:  msg.Path(strings.ToLower(ephostname+"."+key), "coredns"),
-					Host: ep.addr.IP, Port: int(ep.port.Port),
+					Key:  strings.Join([]string{zonePath, "svc", svc.namespace, svc.name, endpointHostname(ep.addr)}, "/"),
+					Host: ep.addr.IP,
+					Port: int(ep.port.Port),
 				}
 				records = append(records, s)
-
 			}
 		} else {
 			// Create records for each exposed port...
 			for _, p := range svc.ports {
-				s := msg.Service{Key: msg.Path(strings.ToLower(key), "coredns"), Host: svc.addr, Port: int(p.Port)}
+				s := msg.Service{
+					Key:  strings.Join([]string{zonePath, "svc", svc.namespace, svc.name}, "/"),
+					Host: svc.addr,
+					Port: int(p.Port)}
 				records = append(records, s)
 			}
 		}
 	}
 
 	for _, p := range pods {
-		key := p.name + "." + p.namespace + ".pod." + zone
 		s := msg.Service{
-			Key:  msg.Path(strings.ToLower(key), "coredns"),
+			Key:  strings.Join([]string{zonePath, "pod", p.namespace, p.name}, "/"),
 			Host: p.addr,
 		}
 		records = append(records, s)
@@ -376,7 +397,7 @@ func ipFromPodName(podname string) string {
 
 func (k *Kubernetes) findPods(namespace, podname string) (pods []pod, err error) {
 	if k.PodMode == PodModeDisabled {
-		return pods, errors.New("pod records disabled")
+		return pods, errPodsDisabled
 	}
 
 	var ip string
@@ -393,16 +414,13 @@ func (k *Kubernetes) findPods(namespace, podname string) (pods []pod, err error)
 	}
 
 	// PodModeVerified
-	objList, err := k.APIConn.podLister.Indexer.ByIndex(podIPIndex, ip)
-	if err != nil {
-		return nil, err
-	}
+	objList := k.APIConn.PodIndex(ip)
 
 	nsWildcard := symbolContainsWildcard(namespace)
 	for _, o := range objList {
 		p, ok := o.(*api.Pod)
 		if !ok {
-			return nil, errors.New("expected type *api.Pod")
+			return nil, errApiBadPodType
 		}
 		// If namespace has a wildcard, filter results against Corefile namespace list.
 		if nsWildcard && (len(k.Namespaces) > 0) && (!dnsstrings.StringInSlice(p.Namespace, k.Namespaces)) {
@@ -461,10 +479,8 @@ func (k *Kubernetes) findServices(r recordRequest) ([]service, error) {
 			continue
 		}
 		// Headless service
-		endpointsList, err := k.APIConn.epLister.List()
-		if err != nil {
-			continue
-		}
+		endpointsList := k.APIConn.EndpointsList()
+
 		for _, ep := range endpointsList.Items {
 			if ep.ObjectMeta.Name != svc.Name || ep.ObjectMeta.Namespace != svc.Namespace {
 				continue
@@ -500,24 +516,19 @@ func symbolMatches(queryString, candidateString string, wildcard bool) bool {
 // If a service cluster ip does not match, it checks all endpoints
 func (k *Kubernetes) getServiceRecordForIP(ip, name string) []msg.Service {
 	// First check services with cluster ips
-	svcList, err := k.APIConn.svcLister.List(labels.Everything())
-	if err != nil {
-		return nil
-	}
+	svcList := k.APIConn.ServiceList()
+
 	for _, service := range svcList {
 		if (len(k.Namespaces) > 0) && !dnsstrings.StringInSlice(service.Namespace, k.Namespaces) {
 			continue
 		}
 		if service.Spec.ClusterIP == ip {
-			domain := service.Name + "." + service.Namespace + ".svc." + k.PrimaryZone()
+			domain := strings.Join([]string{service.Name, service.Namespace, "svc", k.PrimaryZone()}, ".")
 			return []msg.Service{{Host: domain}}
 		}
 	}
 	// If no cluster ips match, search endpoints
-	epList, err := k.APIConn.epLister.List()
-	if err != nil {
-		return nil
-	}
+	epList := k.APIConn.EndpointsList()
 	for _, ep := range epList.Items {
 		if (len(k.Namespaces) > 0) && !dnsstrings.StringInSlice(ep.ObjectMeta.Namespace, k.Namespaces) {
 			continue
@@ -525,7 +536,7 @@ func (k *Kubernetes) getServiceRecordForIP(ip, name string) []msg.Service {
 		for _, eps := range ep.Subsets {
 			for _, addr := range eps.Addresses {
 				if addr.IP == ip {
-					domain := endpointHostname(addr) + "." + ep.ObjectMeta.Name + "." + ep.ObjectMeta.Namespace + ".svc." + k.PrimaryZone()
+					domain := strings.Join([]string{endpointHostname(addr), ep.ObjectMeta.Name, ep.ObjectMeta.Namespace, "svc", k.PrimaryZone()}, ".")
 					return []msg.Service{{Host: domain}}
 				}
 			}