Switch over to k8s notification API (#202)

* Merge notification code by @aledbf and update for recent changes. * Fix travis environment to correctly build with k8s.io and forked repositories. * Refactored kubernetes Corefile parser * Added lots of Corefile parsing tests
2025-10-28 00:34:24 -04:00 · 2016-08-05 18:19:51 -07:00
parent 604d2a3730
commit 6d90b745e0
13 changed files with 609 additions and 237 deletions
--- a/.travis.yml
+++ b/.travis.yml
@@ -25,15 +25,25 @@ before_install:
  - env

 before_script:
+  # Fix repo pathname for golang imports.
+  #   When building in a forked repo the import path will be incorrect.
+  #   Fix is to detect this case and create a symbolic link for the real import name.
+  #   Note: This assumes that both the upstream "real" repo and the fork are hosted
+  #         at the same domain. (eg. github.com)
+  - ( export UPSTREAM="miekg/coredns" && export REPONAME=`pwd | rev | cut -d "/" -f 1-2 | rev` && test "$REPO" != "$UPSTREAM" && mkdir -p ../../`echo $UPSTREAM | cut -d "/" -f 1` && ln -s ../$REPONAME ../../$UPSTREAM )
+  # Download etcd, unpack and launch
  - curl -L  https://github.com/coreos/etcd/releases/download/v2.3.1/etcd-v2.3.1-linux-amd64.tar.gz -o etcd-v2.3.1-linux-amd64.tar.gz
  - tar xzvf etcd-v2.3.1-linux-amd64.tar.gz
  - ./etcd-v2.3.1-linux-amd64/etcd &
-  - go get
-  - go get github.com/coreos/go-etcd/etcd
+  # If docker is available, pull the kubernetes hyperkube image down and launch kubernetes.
  - if which docker &>/dev/null ; then docker pull gcr.io/google_containers/hyperkube-amd64:v1.2.4 ; docker ps -a ; fi
-  - pwd
  - if which docker &>/dev/null ; then ./middleware/kubernetes/test/00_run_k8s.sh && ./middleware/kubernetes/test/10_setup_kubectl.sh && ./middleware/kubernetes/test/20_setup_k8s_services.sh ; docker ps -a ; fi
+  # Get golang dependencies, and build coredns binary
+  - go get -v -d
+  - go get github.com/coreos/go-etcd/etcd
+  - go build -v -ldflags="-s -w"

 script:
  - go test -tags etcd -race -bench=. ./...
+  # Run kubernetes integration tests only if kubectl is available. i.e. If kubernetes was launched
  - ./middleware/kubernetes/test/kubectl version && go test -tags k8s -race -bench=. -run 'TestK8sIntegration' ./test
--- a/18
+++ b/18
@@ -4,13 +4,16 @@ BUILD_VERBOSE := -v
 TEST_VERBOSE :=
 TEST_VERBOSE := -v

+DOCKER_IMAGE_NAME := $$USER/coredns
+
+
 all:
-	go build $(BUILD_VERBOSE)
+	go build $(BUILD_VERBOSE) -ldflags="-s -w"

 .PHONY: docker
-docker:
-	GOOS=linux go build -a -tags netgo -installsuffix netgo
-	docker build -t $$USER/coredns .
+docker: all
+	GOOS=linux go build -a -tags netgo -installsuffix netgo -ldflags="-s -w"
+	docker build -t $(DOCKER_IMAGE_NAME) .

 .PHONY: deps
 deps:
@@ -22,8 +25,15 @@ test:

 .PHONY: testk8s
 testk8s:
+	# With -args --v=100 the k8s API response data will be printed in the log:
+	#go test $(TEST_VERBOSE) -tags=k8s -run 'TestK8sIntegration' ./test -args --v=100
+	# Without the k8s API response data:
 	go test $(TEST_VERBOSE) -tags=k8s -run 'TestK8sIntegration' ./test

+.PHONY: testk8s-setup
+testk8s-setup:
+	go test -v ./core/setup -run TestKubernetes
+
 .PHONY: clean
 clean:
 	go clean
--- a/core/setup/kubernetes.go
+++ b/core/setup/kubernetes.go
@@ -1,32 +1,34 @@
 package setup

 import (
+	"errors"
 	"log"
 	"strings"
+	"time"

 	"github.com/miekg/coredns/middleware"
 	"github.com/miekg/coredns/middleware/kubernetes"
-	k8sc "github.com/miekg/coredns/middleware/kubernetes/k8sclient"
 	"github.com/miekg/coredns/middleware/kubernetes/nametemplate"
-	"github.com/miekg/coredns/middleware/proxy"
 )

 const (
-	defaultK8sEndpoint  = "http://localhost:8080"
 	defaultNameTemplate = "{service}.{namespace}.{zone}"
+	defaultResyncPeriod = 5 * time.Minute
 )

 // Kubernetes sets up the kubernetes middleware.
 func Kubernetes(c *Controller) (middleware.Middleware, error) {
-	log.Printf("[debug] controller %v\n", c)
-	// TODO: Determine if subzone support required
-
 	kubernetes, err := kubernetesParse(c)
-
 	if err != nil {
 		return nil, err
 	}

+	err = kubernetes.StartKubeCache()
+	if err != nil {
+		return nil, err
+	}
+	log.Printf("[debug] after parse and start KubeCache, APIconn is: %v", kubernetes.APIConn)
+
 	return func(next middleware.Handler) middleware.Handler {
 		kubernetes.Next = next
 		return kubernetes
@@ -34,78 +36,73 @@ func Kubernetes(c *Controller) (middleware.Middleware, error) {
 }

 func kubernetesParse(c *Controller) (kubernetes.Kubernetes, error) {
-	k8s := kubernetes.Kubernetes{
-		Proxy: proxy.New([]string{}),
-	}
-	var (
-		endpoints  = []string{defaultK8sEndpoint}
-		template   = defaultNameTemplate
-		namespaces = []string{}
-	)
+	var err error
+	template := defaultNameTemplate

-	k8s.APIConn = k8sc.NewK8sConnector(endpoints[0])
+	k8s := kubernetes.Kubernetes{
+		ResyncPeriod: defaultResyncPeriod,
+	}
 	k8s.NameTemplate = new(nametemplate.NameTemplate)
 	k8s.NameTemplate.SetTemplate(template)

+	// TODO: expose resync period in Corefile
+
 	for c.Next() {
 		if c.Val() == "kubernetes" {
 			zones := c.RemainingArgs()

+			log.Printf("[debug] Zones: %v", zones)
 			if len(zones) == 0 {
 				k8s.Zones = c.ServerBlockHosts
+				log.Printf("[debug] Zones(from ServerBlockHosts): %v", zones)
 			} else {
 				// Normalize requested zones
 				k8s.Zones = kubernetes.NormalizeZoneList(zones)
 			}

-			// TODO: clean this parsing up
-
 			middleware.Zones(k8s.Zones).FullyQualify()
+			if k8s.Zones == nil || len(k8s.Zones) < 1 {
+				err = errors.New("Zone name must be provided for kubernetes middleware.")
+				log.Printf("[debug] %v\n", err)
+				return kubernetes.Kubernetes{}, err
+			}

-			log.Printf("[debug] c data: %v\n", c)
-
-			if c.NextBlock() {
-				// TODO(miek): 2 switches?
-				switch c.Val() {
-				case "endpoint":
-					args := c.RemainingArgs()
-					if len(args) == 0 {
-						return kubernetes.Kubernetes{}, c.ArgErr()
-					}
-					endpoints = args
-					k8s.APIConn = k8sc.NewK8sConnector(endpoints[0])
-				case "namespaces":
-					args := c.RemainingArgs()
-					if len(args) == 0 {
-						return kubernetes.Kubernetes{}, c.ArgErr()
-					}
-					namespaces = args
-					k8s.Namespaces = append(k8s.Namespaces, namespaces...)
-				}
-				for c.Next() {
+			for c.NextBlock() {
 				switch c.Val() {
 				case "template":
 					args := c.RemainingArgs()
-						if len(args) == 0 {
-							return kubernetes.Kubernetes{}, c.ArgErr()
-						}
-						template = strings.Join(args, "")
-						err := k8s.NameTemplate.SetTemplate(template)
+					if len(args) != 0 {
+						template := strings.Join(args, "")
+						err = k8s.NameTemplate.SetTemplate(template)
 						if err != nil {
 							return kubernetes.Kubernetes{}, err
 						}
-					case "namespaces":
-						args := c.RemainingArgs()
-						if len(args) == 0 {
+					} else {
+						log.Printf("[debug] 'template' keyword provided without any template value.")
 						return kubernetes.Kubernetes{}, c.ArgErr()
 					}
-						namespaces = args
-						k8s.Namespaces = append(k8s.Namespaces, namespaces...)
+				case "namespaces":
+					args := c.RemainingArgs()
+					if len(args) != 0 {
+						k8s.Namespaces = append(k8s.Namespaces, args...)
+					} else {
+						log.Printf("[debug] 'namespaces' keyword provided without any namespace values.")
+						return kubernetes.Kubernetes{}, c.ArgErr()
+					}
+				case "endpoint":
+					args := c.RemainingArgs()
+					if len(args) != 0 {
+						k8s.APIEndpoint = args[0]
+					} else {
+						log.Printf("[debug] 'endpoint' keyword provided without any endpoint url value.")
+						return kubernetes.Kubernetes{}, c.ArgErr()
 					}
 				}
 			}
 			return k8s, nil
 		}
 	}
-	return kubernetes.Kubernetes{}, nil
+	err = errors.New("Kubernetes setup called without keyword 'kubernetes' in Corefile")
+	log.Printf("[ERROR] %v\n", err)
+	return kubernetes.Kubernetes{}, err
 }
--- a/core/setup/kubernetes_test.go
+++ b/core/setup/kubernetes_test.go
@@ -5,37 +5,19 @@ import (
 	"testing"
 )

-/*
-kubernetes coredns.local {
-        # Use url for k8s API endpoint
-        endpoint http://localhost:8080
-        # Assemble k8s record names with the template
-        template {service}.{namespace}.{zone}
-        # Only expose the k8s namespace "demo"
-        #namespaces demo
-    }
-*/
-
 func TestKubernetesParse(t *testing.T) {
 	tests := []struct {
+		description        string
 		input              string
 		shouldErr          bool
 		expectedErrContent string // substring from the expected error. Empty for positive cases.
-		expectedZoneCount  int    // expected count of defined zones. '-1' for negative cases.
+		expectedZoneCount  int    // expected count of defined zones.
 		expectedNTValid    bool   // NameTemplate to be initialized and valid
-		expectedNSCount    int    // expected count of namespaces. '-1' for negative cases.
+		expectedNSCount    int    // expected count of namespaces.
 	}{
 		// positive
-		// TODO: not specifiying a zone maybe should error out.
-		{
-			`kubernetes`,
-			false,
-			"",
-			0,
-			true,
-			0,
-		},
 		{
+			"kubernetes keyword with one zone",
 			`kubernetes coredns.local`,
 			false,
 			"",
@@ -44,6 +26,7 @@ func TestKubernetesParse(t *testing.T) {
 			0,
 		},
 		{
+			"kubernetes keyword with multiple zones",
 			`kubernetes coredns.local test.local`,
 			false,
 			"",
@@ -52,6 +35,17 @@ func TestKubernetesParse(t *testing.T) {
 			0,
 		},
 		{
+			"kubernetes keyword with zone and empty braces",
+			`kubernetes coredns.local {
+}`,
+			false,
+			"",
+			1,
+			true,
+			0,
+		},
+		{
+			"endpoint keyword with url",
 			`kubernetes coredns.local {
 	endpoint http://localhost:9090
 }`,
@@ -62,6 +56,7 @@ func TestKubernetesParse(t *testing.T) {
 			0,
 		},
 		{
+			"template keyword with valid template",
 			`kubernetes coredns.local {
 	template {service}.{namespace}.{zone}
 }`,
@@ -72,6 +67,7 @@ func TestKubernetesParse(t *testing.T) {
 			0,
 		},
 		{
+			"namespaces keyword with one namespace",
 			`kubernetes coredns.local {
 	namespaces demo
 }`,
@@ -82,6 +78,7 @@ func TestKubernetesParse(t *testing.T) {
 			1,
 		},
 		{
+			"namespaces keyword with multiple namespaces",
 			`kubernetes coredns.local {
 	namespaces demo test
 }`,
@@ -91,9 +88,40 @@ func TestKubernetesParse(t *testing.T) {
 			true,
 			2,
 		},
-
+		{
+			"fully specified valid config",
+			`kubernetes coredns.local test.local {
+	endpoint http://localhost:8080
+	template {service}.{namespace}.{zone}
+	namespaces demo test
+}`,
+			false,
+			"",
+			2,
+			true,
+			2,
+		},
 		// negative
 		{
+			"no kubernetes keyword",
+			"",
+			true,
+			"Kubernetes setup called without keyword 'kubernetes' in Corefile",
+			-1,
+			false,
+			-1,
+		},
+		{
+			"kubernetes keyword without a zone",
+			`kubernetes`,
+			true,
+			"Zone name must be provided for kubernetes middleware",
+			-1,
+			true,
+			0,
+		},
+		{
+			"endpoint keyword without an endpoint value",
 			`kubernetes coredns.local {
    endpoint
 }`,
@@ -103,56 +131,56 @@ func TestKubernetesParse(t *testing.T) {
 			true,
 			-1,
 		},
-		// No template provided for template line.
 		{
+			"template keyword without a template value",
 			`kubernetes coredns.local {
    template
 }`,
 			true,
-			"",
+			"Wrong argument count or unexpected line ending after 'template'",
 			-1,
 			false,
-			-1,
+			0,
 		},
-		// Invalid template provided
 		{
+			"template keyword with an invalid template value",
 			`kubernetes coredns.local {
    template {namespace}.{zone}
 }`,
 			true,
-			"",
+			"Record name template does not pass NameTemplate validation",
 			-1,
 			false,
-			-1,
+			0,
 		},
-		/*
-			 		// No valid provided for namespaces
 		{
+			"namespace keyword without a namespace value",
 			`kubernetes coredns.local {
 	namespaces
 }`,
 			true,
-			   			"",
+			"Parse error: Wrong argument count or unexpected line ending after 'namespaces'",
 			-1,
 			true,
 			-1,
 		},
-		*/
 	}

+	t.Logf("Parser test cases count: %v", len(tests))
 	for i, test := range tests {
 		c := NewTestController(test.input)
 		k8sController, err := kubernetesParse(c)
-		t.Logf("i: %v\n", i)
-		t.Logf("controller: %v\n", k8sController)
+		t.Logf("setup test: %2v -- %v\n", i, test.description)
+		//t.Logf("controller: %v\n", k8sController)

 		if test.shouldErr && err == nil {
-			t.Errorf("Test %d: Expected error, but found one for input '%s'. Error was: '%v'", i, test.input, err)
+			t.Errorf("Test %d: Expected error, but did not find error for input '%s'. Error was: '%v'", i, test.input, err)
 		}

 		if err != nil {
 			if !test.shouldErr {
 				t.Errorf("Test %d: Expected no error but found one for input %s. Error was: %v", i, test.input, err)
+				continue
 			}

 			if test.shouldErr && (len(test.expectedErrContent) < 1) {
@@ -160,14 +188,13 @@ func TestKubernetesParse(t *testing.T) {
 			}

 			if test.shouldErr && (test.expectedZoneCount >= 0) {
-				t.Fatalf("Test %d: Test marked as expecting an error, but provides value for expectedZoneCount!=-1 for input '%s'. Error was: '%v'", i, test.input, err)
+				t.Errorf("Test %d: Test marked as expecting an error, but provides value for expectedZoneCount!=-1 for input '%s'. Error was: '%v'", i, test.input, err)
 			}

 			if !strings.Contains(err.Error(), test.expectedErrContent) {
 				t.Errorf("Test %d: Expected error to contain: %v, found error: %v, input: %s", i, test.expectedErrContent, err, test.input)
 			}
-
-			return
+			continue
 		}

 		// No error was raised, so validate initialization of k8sController
@@ -191,7 +218,8 @@ func TestKubernetesParse(t *testing.T) {
 		foundNSCount := len(k8sController.Namespaces)
 		if foundNSCount != test.expectedNSCount {
 			t.Errorf("Test %d: Expected kubernetes controller to be initialized with %d namespaces. Instead found %d namespaces: '%v' for input '%s'", i, test.expectedNSCount, foundNSCount, k8sController.Namespaces, test.input)
-		}
-
+			t.Logf("k8sController is: %v", k8sController)
+			t.Logf("k8sController.Namespaces is: %v", k8sController.Namespaces)
+		}
 	}
 }
--- a/kubernetes-rc.yaml
+++ b/kubernetes-rc.yaml
@@ -0,0 +1,70 @@
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: coredns-configmap
+  namespace: kube-system
+data:
+  corefile: |
+    .:53 {
+      kubernetes coredns.local {
+      }
+      #cache 160 coredns.local
+      errors stdout
+      log stdout
+    }
+---
+apiVersion: v1
+kind: ReplicationController
+metadata:
+  labels:
+    k8s-app: kube-dns
+    kubernetes.io/cluster-service: "true"
+    version: v20
+  name: kube-dns-v20
+  namespace: kube-system
+spec:
+  replicas: 1
+  selector:
+    k8s-app: kube-dns
+    version: v20
+  template:
+    metadata:
+      labels:
+        k8s-app: kube-dns
+        kubernetes.io/cluster-service: "true"
+        version: v20
+    spec:
+      containers:
+      - args:
+        - -conf=/cfg/corefile
+        image: aledbf/kube-coredns:0.6
+        imagePullPolicy: IfNotPresent
+        name: kube-dns
+        ports:
+        - containerPort: 53
+          name: dns
+          protocol: UDP
+        - containerPort: 53
+          name: dns-tcp
+          protocol: TCP
+        volumeMounts:
+        - name: config-volume
+          mountPath: /cfg
+      - args:
+        - -cmd=nslookup kubernetes.default.svc.cluster.local localhost >/dev/null
+        - -port=8080
+        image: gcr.io/google_containers/exechealthz:1.0
+        imagePullPolicy: IfNotPresent
+        name: healthz
+        ports:
+        - containerPort: 8080
+          protocol: TCP
+        resources:
+          limits:
+            cpu: 10m
+            memory: 20Mi
+      dnsPolicy: Default
+      volumes:
+        - name: config-volume
+          configMap:
+            name: coredns-configmap
--- a/middleware/kubernetes/README.md
+++ b/middleware/kubernetes/README.md
@@ -276,11 +276,13 @@ TBD:
 		* Update kubernetes middleware documentation to describe running CoreDNS as a
 		  SkyDNS replacement. (Include descriptions of different ways to pass CoreFile
 		  to coredns command.)
+		* Remove dependency on healthz for health checking in
+		  `kubernetes-rc.yaml` file.
 		* Expose load-balancer IP addresses.
 		* Calculate SRV priority based on number of instances running.
 		  (See SkyDNS README.md)
 	* Functional work
-		* (done) ~~Implement wildcard-based lookup. Minimally support `*`, consider `?` as well.~~
+		* (done. '?' not supported yet) ~~Implement wildcard-based lookup. Minimally support `*`, consider `?` as well.~~
        * (done) ~~Note from Miek on PR 181: "SkyDNS also supports the word `any`.~~
 		* Implement SkyDNS-style synthetic zones such as "svc" to group k8s objects. (This
 		  should be optional behavior.) Also look at "pod" synthetic zones.
@@ -303,17 +305,14 @@ TBD:
 	* Performance
 		* Improve lookup to reduce size of query result obtained from k8s API.
 		  (namespace-based?, other ideas?)
-		* Caching of k8s API dataset.
+		* Caching/notification of k8s API dataset. (See aledbf fork for
+		  implementation ideas.)
 		* DNS response caching is good, but we should also cache at the http query 
 		  level as well. (Take a look at https://github.com/patrickmn/go-cache as 
 		  a potential expiring cache implementation for the http API queries.)
-		* Push notifications from k8s for data changes rather than pull via API?
 * Additional features:
-	* Implement namespace filtering to different zones. That is, zone "a.b"
-	  publishes services from namespace "foo", and zone "x.y" publishes services
-	  from namespaces "bar" and "baz". (Basic version implemented -- need test cases.)
 	* Reverse IN-ADDR entries for services. (Is there any value in supporting 
-	  reverse lookup records?
+	  reverse lookup records?)
 	* How to support label specification in Corefile to allow use of labels to 
 	  indicate zone? (Is this even useful?) For example, the following
 	  configuration exposes all services labeled for the "staging" environment
@@ -334,11 +333,14 @@ TBD:
 	  flattening to lower case and mapping of non-DNS characters to DNS characters
 	  in a standard way.)
 	* Expose arbitrary kubernetes repository data as TXT records?
-	* Support custom user-provided templates for k8s names. A string provided
+	* (done) ~~Support custom user-provided templates for k8s names. A string provided
 	  in the middleware configuration like `{service}.{namespace}.{type}` defines
 	  the template of how to construct record names for the zone. This example
 	  would produce `myservice.mynamespace.svc.cluster.local`. (Basic template
-	  implemented. Need to slice zone out of current template implementation.)
+	  implemented. Need to slice zone out of current template implementation.)~~
+	* (done) ~~Implement namespace filtering to different zones. That is, zone "a.b"
+	  publishes services from namespace "foo", and zone "x.y" publishes services
+	  from namespaces "bar" and "baz". (Basic version implemented -- need test cases.)~~
 * DNS Correctness
 	* Do we need to generate synthetic zone records for namespaces?
 	* Do we need to generate synthetic zone records for the skydns synthetic zones?
@@ -347,10 +349,10 @@ TBD:
 	  using the `cache` directive. Tested working using 20s cache timeout
 	  and A-record queries. Automate testing with cache in place.
 	* Automate CoreDNS performance tests. Initially for zone files, and for
-	  pre-loaded k8s API cache.
+	  pre-loaded k8s API cache. With and without CoreDNS response caching.
    * Try to get rid of kubernetes launch scripts by moving operations into
      .travis.yml file.
 	* ~~Implement test cases for http data parsing using dependency injection
 	  for http get operations.~~
-    * ~~Automate integration testing with kubernetes. (k8s launch and service start-up
-      automation is in middleware/kubernetes/tests)~~
+    * ~~Automate integration testing with kubernetes. (k8s launch and service
+      start-up automation is in middleware/kubernetes/tests)~~
--- a/middleware/kubernetes/controller.go
+++ b/middleware/kubernetes/controller.go
@@ -0,0 +1,195 @@
+package kubernetes
+
+import (
+	"fmt"
+	"log"
+	"sync"
+	"time"
+
+	"github.com/miekg/coredns/middleware/kubernetes/util"
+
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/client/cache"
+	client "k8s.io/kubernetes/pkg/client/unversioned"
+	"k8s.io/kubernetes/pkg/controller/framework"
+	"k8s.io/kubernetes/pkg/runtime"
+	"k8s.io/kubernetes/pkg/watch"
+)
+
+var (
+	namespace = api.NamespaceAll
+)
+
+type dnsController struct {
+	client *client.Client
+
+	endpController *framework.Controller
+	svcController  *framework.Controller
+	nsController   *framework.Controller
+
+	svcLister  cache.StoreToServiceLister
+	endpLister cache.StoreToEndpointsLister
+	nsLister   util.StoreToNamespaceLister
+
+	// stopLock is used to enforce only a single call to Stop is active.
+	// Needed because we allow stopping through an http endpoint and
+	// allowing concurrent stoppers leads to stack traces.
+	stopLock sync.Mutex
+	shutdown bool
+	stopCh   chan struct{}
+}
+
+// newDNSController creates a controller for coredns
+func newdnsController(kubeClient *client.Client, resyncPeriod time.Duration) *dnsController {
+	dns := dnsController{
+		client: kubeClient,
+		stopCh: make(chan struct{}),
+	}
+
+	dns.endpLister.Store, dns.endpController = framework.NewInformer(
+		&cache.ListWatch{
+			ListFunc:  endpointsListFunc(dns.client, namespace),
+			WatchFunc: endpointsWatchFunc(dns.client, namespace),
+		},
+		&api.Endpoints{}, resyncPeriod, framework.ResourceEventHandlerFuncs{})
+
+	dns.svcLister.Store, dns.svcController = framework.NewInformer(
+		&cache.ListWatch{
+			ListFunc:  serviceListFunc(dns.client, namespace),
+			WatchFunc: serviceWatchFunc(dns.client, namespace),
+		},
+		&api.Service{}, resyncPeriod, framework.ResourceEventHandlerFuncs{})
+
+	dns.nsLister.Store, dns.nsController = framework.NewInformer(
+		&cache.ListWatch{
+			ListFunc:  namespaceListFunc(dns.client),
+			WatchFunc: namespaceWatchFunc(dns.client),
+		},
+		&api.Namespace{}, resyncPeriod, framework.ResourceEventHandlerFuncs{})
+
+	return &dns
+}
+
+func serviceListFunc(c *client.Client, ns string) func(api.ListOptions) (runtime.Object, error) {
+	return func(opts api.ListOptions) (runtime.Object, error) {
+		return c.Services(ns).List(opts)
+	}
+}
+
+func serviceWatchFunc(c *client.Client, ns string) func(options api.ListOptions) (watch.Interface, error) {
+	return func(options api.ListOptions) (watch.Interface, error) {
+		return c.Services(ns).Watch(options)
+	}
+}
+
+func endpointsListFunc(c *client.Client, ns string) func(api.ListOptions) (runtime.Object, error) {
+	return func(opts api.ListOptions) (runtime.Object, error) {
+		return c.Endpoints(ns).List(opts)
+	}
+}
+
+func endpointsWatchFunc(c *client.Client, ns string) func(options api.ListOptions) (watch.Interface, error) {
+	return func(options api.ListOptions) (watch.Interface, error) {
+		return c.Endpoints(ns).Watch(options)
+	}
+}
+
+func namespaceListFunc(c *client.Client) func(api.ListOptions) (runtime.Object, error) {
+	return func(opts api.ListOptions) (runtime.Object, error) {
+		return c.Namespaces().List(opts)
+	}
+}
+
+func namespaceWatchFunc(c *client.Client) func(options api.ListOptions) (watch.Interface, error) {
+	return func(options api.ListOptions) (watch.Interface, error) {
+		return c.Namespaces().Watch(options)
+	}
+}
+
+func (dns *dnsController) controllersInSync() bool {
+	return dns.svcController.HasSynced() && dns.endpController.HasSynced()
+}
+
+// Stop stops the  controller.
+func (dns *dnsController) Stop() error {
+	dns.stopLock.Lock()
+	defer dns.stopLock.Unlock()
+
+	// Only try draining the workqueue if we haven't already.
+	if !dns.shutdown {
+		close(dns.stopCh)
+		log.Println("shutting down controller queues")
+		dns.shutdown = true
+
+		return nil
+	}
+
+	return fmt.Errorf("shutdown already in progress")
+}
+
+// Run starts the controller.
+func (dns *dnsController) Run() {
+	log.Println("[debug] starting coredns controller")
+
+	go dns.endpController.Run(dns.stopCh)
+	go dns.svcController.Run(dns.stopCh)
+	go dns.nsController.Run(dns.stopCh)
+
+	<-dns.stopCh
+	log.Println("[debug] shutting down coredns controller")
+}
+
+func (dns *dnsController) GetNamespaceList() *api.NamespaceList {
+	nsList, err := dns.nsLister.List()
+	if err != nil {
+		return &api.NamespaceList{}
+	}
+
+	return &nsList
+}
+
+func (dns *dnsController) GetServiceList() *api.ServiceList {
+	log.Printf("[debug] here in GetServiceList")
+	svcList, err := dns.svcLister.List()
+	if err != nil {
+		return &api.ServiceList{}
+	}
+
+	return &svcList
+}
+
+// GetServicesByNamespace returns a map of
+// namespacename :: [ kubernetesService ]
+func (dns *dnsController) GetServicesByNamespace() map[string][]api.Service {
+	k8sServiceList := dns.GetServiceList()
+	if k8sServiceList == nil {
+		return nil
+	}
+
+	items := make(map[string][]api.Service, len(k8sServiceList.Items))
+	for _, i := range k8sServiceList.Items {
+		namespace := i.Namespace
+		items[namespace] = append(items[namespace], i)
+	}
+
+	return items
+}
+
+// GetServiceInNamespace returns the Service that matches
+// servicename in the namespace
+func (dns *dnsController) GetServiceInNamespace(namespace string, servicename string) *api.Service {
+	svcKey := fmt.Sprintf("%v/%v", namespace, servicename)
+	svcObj, svcExists, err := dns.svcLister.Store.GetByKey(svcKey)
+
+	if err != nil {
+		log.Printf("error getting service %v from the cache: %v\n", svcKey, err)
+		return nil
+	}
+
+	if !svcExists {
+		log.Printf("service %v does not exists\n", svcKey)
+		return nil
+	}
+
+	return svcObj.(*api.Service)
+}
--- a/middleware/kubernetes/handler.go
+++ b/middleware/kubernetes/handler.go
@@ -3,6 +3,7 @@ package kubernetes
 import (
 	"fmt"
 	"log"
+	"strings"

 	"github.com/miekg/coredns/middleware"

@@ -18,6 +19,26 @@ func (k Kubernetes) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.M
 		return dns.RcodeServerFailure, fmt.Errorf("can only deal with ClassINET")
 	}

+	m := new(dns.Msg)
+	m.SetReply(r)
+	m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
+
+	// TODO: find an alternative to this block
+	if strings.HasSuffix(state.Name(), arpaSuffix) {
+		ip, _ := extractIP(state.Name())
+		records := k.getServiceRecordForIP(ip, state.Name())
+		if len(records) > 0 {
+			srvPTR := &records[0]
+			m.Answer = append(m.Answer, srvPTR.NewPTR(state.QName(), ip))
+
+			m = dedup(m)
+			state.SizeAndDo(m)
+			m, _ = state.Scrub(m)
+			w.WriteMsg(m)
+			return dns.RcodeSuccess, nil
+		}
+	}
+
 	// Check that query matches one of the zones served by this middleware,
 	// otherwise delegate to the next in the pipeline.
 	zone := middleware.Zones(k.Zones).Matches(state.Name())
@@ -28,10 +49,6 @@ func (k Kubernetes) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.M
 		return k.Next.ServeDNS(ctx, w, r)
 	}

-	m := new(dns.Msg)
-	m.SetReply(r)
-	m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
-
 	var (
 		records, extra []dns.RR
 		err            error
--- a/middleware/kubernetes/kubernetes.go
+++ b/middleware/kubernetes/kubernetes.go
@@ -4,33 +4,70 @@ package kubernetes
 import (
 	"errors"
 	"log"
+	"strings"
 	"time"

 	"github.com/miekg/coredns/middleware"
-	k8sc "github.com/miekg/coredns/middleware/kubernetes/k8sclient"
 	"github.com/miekg/coredns/middleware/kubernetes/msg"
 	"github.com/miekg/coredns/middleware/kubernetes/nametemplate"
 	"github.com/miekg/coredns/middleware/kubernetes/util"
 	"github.com/miekg/coredns/middleware/proxy"

 	"github.com/miekg/dns"
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/client/unversioned"
+	"k8s.io/kubernetes/pkg/client/unversioned/clientcmd"
+	clientcmdapi "k8s.io/kubernetes/pkg/client/unversioned/clientcmd/api"
+)
+
+const (
+	defaultResyncPeriod = 5 * time.Minute
 )

 type Kubernetes struct {
 	Next         middleware.Handler
 	Zones        []string
 	Proxy        proxy.Proxy // Proxy for looking up names during the resolution process
-	APIConn      *k8sc.K8sConnector
+	APIEndpoint  string
+	APIConn      *dnsController
+	ResyncPeriod time.Duration
 	NameTemplate *nametemplate.NameTemplate
 	Namespaces   []string
 }

+func (g *Kubernetes) StartKubeCache() error {
+	// For a custom api server or running outside a k8s cluster
+	// set URL in env.KUBERNETES_MASTER
+	loadingRules := clientcmd.NewDefaultClientConfigLoadingRules()
+	overrides := &clientcmd.ConfigOverrides{}
+	if len(g.APIEndpoint) > 0 {
+		overrides.ClusterInfo = clientcmdapi.Cluster{Server: g.APIEndpoint}
+	}
+	clientConfig := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(loadingRules, overrides)
+	config, err := clientConfig.ClientConfig()
+	if err != nil {
+		log.Printf("[debug] error connecting to the client: %v", err)
+		return err
+	}
+	kubeClient, err := unversioned.New(config)
+
+	if err != nil {
+		log.Printf("[ERROR] Failed to create kubernetes notification controller: %v", err)
+		return err
+	}
+	g.APIConn = newdnsController(kubeClient, g.ResyncPeriod)
+
+	go g.APIConn.Run()
+
+	return err
+}
+
 // getZoneForName returns the zone string that matches the name and a
 // list of the DNS labels from name that are within the zone.
 // For example, if "coredns.local" is a zone configured for the
 // Kubernetes middleware, then getZoneForName("a.b.coredns.local")
 // will return ("coredns.local", ["a", "b"]).
-func (g Kubernetes) getZoneForName(name string) (string, []string) {
+func (g *Kubernetes) getZoneForName(name string) (string, []string) {
 	var zone string
 	var serviceSegments []string

@@ -51,7 +88,14 @@ func (g Kubernetes) getZoneForName(name string) (string, []string) {
 // If exact is true, it will lookup just
 // this name. This is used when find matches when completing SRV lookups
 // for instance.
-func (g Kubernetes) Records(name string, exact bool) ([]msg.Service, error) {
+func (g *Kubernetes) Records(name string, exact bool) ([]msg.Service, error) {
+	// TODO: refector this.
+	// Right now GetNamespaceFromSegmentArray do not supports PRE queries
+	if strings.HasSuffix(name, arpaSuffix) {
+		ip, _ := extractIP(name)
+		records := g.getServiceRecordForIP(ip, name)
+		return records, nil
+	}
 	var (
 		serviceName string
 		namespace   string
@@ -99,6 +143,7 @@ func (g Kubernetes) Records(name string, exact bool) ([]msg.Service, error) {
 		return nil, nil
 	}

+	log.Printf("before g.Get(namespace, nsWildcard, serviceName, serviceWildcard): %v %v %v %v", namespace, nsWildcard, serviceName, serviceWildcard)
 	k8sItems, err := g.Get(namespace, nsWildcard, serviceName, serviceWildcard)
 	log.Printf("[debug] k8s items: %v\n", k8sItems)
 	if err != nil {
@@ -115,7 +160,7 @@ func (g Kubernetes) Records(name string, exact bool) ([]msg.Service, error) {
 }

 // TODO: assemble name from parts found in k8s data based on name template rather than reusing query string
-func (g Kubernetes) getRecordsForServiceItems(serviceItems []k8sc.ServiceItem, values nametemplate.NameValues) []msg.Service {
+func (g *Kubernetes) getRecordsForServiceItems(serviceItems []api.Service, values nametemplate.NameValues) []msg.Service {
 	var records []msg.Service

 	for _, item := range serviceItems {
@@ -131,7 +176,7 @@ func (g Kubernetes) getRecordsForServiceItems(serviceItems []k8sc.ServiceItem, v
 		// Create records for each exposed port...
 		for _, p := range item.Spec.Ports {
 			log.Printf("[debug]    port: %v\n", p.Port)
-			s := msg.Service{Host: clusterIP, Port: p.Port}
+			s := msg.Service{Host: clusterIP, Port: int(p.Port)}
 			records = append(records, s)
 		}
 	}
@@ -141,22 +186,24 @@ func (g Kubernetes) getRecordsForServiceItems(serviceItems []k8sc.ServiceItem, v
 }

 // Get performs the call to the Kubernetes http API.
-func (g Kubernetes) Get(namespace string, nsWildcard bool, servicename string, serviceWildcard bool) ([]k8sc.ServiceItem, error) {
-	serviceList, err := g.APIConn.GetServiceList()
+func (g *Kubernetes) Get(namespace string, nsWildcard bool, servicename string, serviceWildcard bool) ([]api.Service, error) {
+	serviceList := g.APIConn.GetServiceList()

+	/* TODO: Remove?
 	if err != nil {
 		log.Printf("[ERROR] Getting service list produced error: %v", err)
 		return nil, err
 	}
+	*/

-	var resultItems []k8sc.ServiceItem
+	var resultItems []api.Service

 	for _, item := range serviceList.Items {
-		if symbolMatches(namespace, item.Metadata.Namespace, nsWildcard) && symbolMatches(servicename, item.Metadata.Name, serviceWildcard) {
+		if symbolMatches(namespace, item.Namespace, nsWildcard) && symbolMatches(servicename, item.Name, serviceWildcard) {
 			// If namespace has a wildcard, filter results against Corefile namespace list.
 			// (Namespaces without a wildcard were filtered before the call to this function.)
-			if nsWildcard && (len(g.Namespaces) > 0) && (!util.StringInSlice(item.Metadata.Namespace, g.Namespaces)) {
-				log.Printf("[debug] Namespace '%v' is not published by Corefile\n", item.Metadata.Namespace)
+			if nsWildcard && (len(g.Namespaces) > 0) && (!util.StringInSlice(item.Namespace, g.Namespaces)) {
+				log.Printf("[debug] Namespace '%v' is not published by Corefile\n", item.Namespace)
 				continue
 			}
 			resultItems = append(resultItems, item)
@@ -179,104 +226,26 @@ func symbolMatches(queryString string, candidateString string, wildcard bool) bo
 	return result
 }

-// TODO: Remove these unused functions. One is related to Ttl calculation
-//       Implement Ttl and priority calculation based on service count before
-//       removing this code.
-/*
-// splitDNSName separates the name into DNS segments and reverses the segments.
-func (g Kubernetes) splitDNSName(name string) []string {
-	l := dns.SplitDomainName(name)
-
-	for i, j := 0, len(l)-1; i < j; i, j = i+1, j-1 {
-		l[i], l[j] = l[j], l[i]
-	}
-
-	return l
-}
-*/
-// skydns/local/skydns/east/staging/web
-// skydns/local/skydns/west/production/web
-//
-// skydns/local/skydns/*/*/web
-// skydns/local/skydns/*/web
-/*
-// loopNodes recursively loops through the nodes and returns all the values. The nodes' keyname
-// will be match against any wildcards when star is true.
-func (g Kubernetes) loopNodes(ns []*etcdc.Node, nameParts []string, star bool, bx map[msg.Service]bool) (sx []msg.Service, err error) {
-	if bx == nil {
-		bx = make(map[msg.Service]bool)
-	}
-Nodes:
-	for _, n := range ns {
-		if n.Dir {
-			nodes, err := g.loopNodes(n.Nodes, nameParts, star, bx)
-			if err != nil {
-				return nil, err
-			}
-			sx = append(sx, nodes...)
-			continue
-		}
-		if star {
-			keyParts := strings.Split(n.Key, "/")
-			for i, n := range nameParts {
-				if i > len(keyParts)-1 {
-					// name is longer than key
-					continue Nodes
-				}
-				if n == "*" || n == "any" {
-					continue
-				}
-				if keyParts[i] != n {
-					continue Nodes
-				}
-			}
-		}
-		serv := new(msg.Service)
-		if err := json.Unmarshal([]byte(n.Value), serv); err != nil {
-			return nil, err
-		}
-		b := msg.Service{Host: serv.Host, Port: serv.Port, Priority: serv.Priority, Weight: serv.Weight, Text: serv.Text, Key: n.Key}
-		if _, ok := bx[b]; ok {
-			continue
-		}
-		bx[b] = true
-
-		serv.Key = n.Key
-		serv.Ttl = g.Ttl(n, serv)
-		if serv.Priority == 0 {
-			serv.Priority = priority
-		}
-		sx = append(sx, *serv)
-	}
-	return sx, nil
-}
-
-// Ttl returns the smaller of the kubernetes TTL and the service's
-// TTL. If neither of these are set (have a zero value), a default is used.
-func (g Kubernetes) Ttl(node *etcdc.Node, serv *msg.Service) uint32 {
-	kubernetesTtl := uint32(node.TTL)
-
-	if kubernetesTtl == 0 && serv.Ttl == 0 {
-		return ttl
-	}
-	if kubernetesTtl == 0 {
-		return serv.Ttl
-	}
-	if serv.Ttl == 0 {
-		return kubernetesTtl
-	}
-	if kubernetesTtl < serv.Ttl {
-		return kubernetesTtl
-	}
-	return serv.Ttl
-}
-*/
-
 // kubernetesNameError checks if the error is ErrorCodeKeyNotFound from kubernetes.
 func isKubernetesNameError(err error) bool {
 	return false
 }

+func (g *Kubernetes) getServiceRecordForIP(ip, name string) []msg.Service {
+	svcList, err := g.APIConn.svcLister.List()
+	if err != nil {
+		return nil
+	}
+
+	for _, service := range svcList.Items {
+		if service.Spec.ClusterIP == ip {
+			return []msg.Service{msg.Service{Host: ip}}
+		}
+	}
+
+	return nil
+}
+
 const (
 	priority   = 10  // default priority when nothing is set
 	ttl        = 300 // default ttl when nothing is set
--- a/middleware/kubernetes/lookup.go
+++ b/middleware/kubernetes/lookup.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"math"
 	"net"
+	"strings"
 	"time"

 	"github.com/miekg/coredns/middleware"
@@ -12,6 +13,11 @@ import (
 	"github.com/miekg/dns"
 )

+const (
+	// arpaSuffix is the standard suffix for PTR IP reverse lookups.
+	arpaSuffix = ".in-addr.arpa."
+)
+
 func (k Kubernetes) records(state middleware.State, exact bool) ([]msg.Service, error) {
 	services, err := k.Records(state.Name(), exact)
 	if err != nil {
@@ -64,13 +70,13 @@ func (k Kubernetes) A(zone string, state middleware.State, previousRecords []dns
 				// We should already have found it
 				continue
 			}
-			m1, e1 := k.Proxy.Lookup(state, target, state.QType())
-			if e1 != nil {
+			mes, err := k.Proxy.Lookup(state, target, state.QType())
+			if err != nil {
 				continue
 			}
-			// Len(m1.Answer) > 0 here is well?
+			// Len(mes.Answer) > 0 here is well?
 			records = append(records, newRecord)
-			records = append(records, m1.Answer...)
+			records = append(records, mes.Answer...)
 			continue
 		case ip.To4() != nil:
 			records = append(records, serv.NewA(state.QName(), ip.To4()))
@@ -285,7 +291,33 @@ func (k Kubernetes) SOA(zone string, state middleware.State) *dns.SOA {
 	}
 }

-// TODO(miek): DNSKEY and friends... intercepted by the DNSSEC middleware?
+func (k Kubernetes) PTR(zone string, state middleware.State) ([]dns.RR, error) {
+	reverseIP, ok := extractIP(state.Name())
+	if !ok {
+		return nil, fmt.Errorf("does not support reverse lookup for %s", state.QName())
+	}
+
+	records := make([]dns.RR, 1)
+	services, err := k.records(state, false)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, serv := range services {
+		ip := net.ParseIP(serv.Host)
+		if reverseIP != serv.Host {
+			continue
+		}
+		switch {
+		case ip.To4() != nil:
+			records = append(records, serv.NewPTR(state.QName(), ip.To4().String()))
+			break
+		case ip.To4() == nil:
+			// nodata?
+		}
+	}
+	return records, nil
+}

 func isDuplicateCNAME(r *dns.CNAME, records []dns.RR) bool {
 	for _, rec := range records {
@@ -300,6 +332,27 @@ func isDuplicateCNAME(r *dns.CNAME, records []dns.RR) bool {

 func copyState(state middleware.State, target string, typ uint16) middleware.State {
 	state1 := middleware.State{W: state.W, Req: state.Req.Copy()}
-	state1.Req.Question[0] = dns.Question{dns.Fqdn(target), dns.ClassINET, typ}
+	state1.Req.Question[0] = dns.Question{Name: dns.Fqdn(target), Qtype: dns.ClassINET, Qclass: typ}
 	return state1
 }
+
+// extractIP turns a standard PTR reverse record lookup name
+// into an IP address
+func extractIP(reverseName string) (string, bool) {
+	if !strings.HasSuffix(reverseName, arpaSuffix) {
+		return "", false
+	}
+	search := strings.TrimSuffix(reverseName, arpaSuffix)
+
+	// reverse the segments and then combine them
+	segments := reverseArray(strings.Split(search, "."))
+	return strings.Join(segments, "."), true
+}
+
+func reverseArray(arr []string) []string {
+	for i := 0; i < len(arr)/2; i++ {
+		j := len(arr) - i - 1
+		arr[i], arr[j] = arr[j], arr[i]
+	}
+	return arr
+}
--- a/middleware/kubernetes/msg/service.go
+++ b/middleware/kubernetes/msg/service.go
@@ -77,6 +77,11 @@ func (s *Service) NewNS(name string) *dns.NS {
 	return &dns.NS{Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeNS, Class: dns.ClassINET, Ttl: s.Ttl}, Ns: host}
 }

+// NewPTR returns a new PTR record based on the Service.
+func (s *Service) NewPTR(name string, target string) *dns.PTR {
+	return &dns.PTR{Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypePTR, Class: dns.ClassINET, Ttl: s.Ttl}, Ptr: dns.Fqdn(target)}
+}
+
 // Group checks the services in sx, it looks for a Group attribute on the shortest
 // keys. If there are multiple shortest keys *and* the group attribute disagrees (and
 // is not empty), we don't consider it a group.
--- a/middleware/kubernetes/test/20_setup_k8s_services.sh
+++ b/middleware/kubernetes/test/20_setup_k8s_services.sh
@@ -69,7 +69,7 @@ run_and_expose_service() {

 wait_until_k8s_ready

-NAMESPACES="demo test"
+NAMESPACES="demo poddemo test"
 create_namespaces

 echo ""
--- a/middleware/kubernetes/util/util.go
+++ b/middleware/kubernetes/util/util.go
@@ -3,6 +3,9 @@ package util

 import (
 	"strings"
+
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/client/cache"
 )

 // StringInSlice check whether string a is a member of slice.
@@ -24,3 +27,16 @@ const (
 	WildcardStar = "*"
 	WildcardAny  = "any"
 )
+
+// StoreToNamespaceLister makes a Store that lists Namespaces.
+type StoreToNamespaceLister struct {
+	cache.Store
+}
+
+// List lists all Namespaces in the store.
+func (s *StoreToNamespaceLister) List() (ns api.NamespaceList, err error) {
+	for _, m := range s.Store.List() {
+		ns.Items = append(ns.Items, *(m.(*api.Namespace)))
+	}
+	return ns, nil
+}