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

middleware/kubernetes/ns_test.go

@@ -0,0 +1,133 @@
+package kubernetes
+
+import "testing"
+import "net"
+
+import "github.com/coredns/coredns/middleware/etcd/msg"
+import "k8s.io/client-go/1.5/pkg/api"
+import "github.com/miekg/dns"
+
+func TestRecordForNS(t *testing.T) {
+	k := Kubernetes{Zones: []string{"inter.webs.test"}}
+	corednsRecord.Hdr.Name = "coredns.kube-system."
+	corednsRecord.A = net.IP("1.2.3.4")
+	r, _ := k.parseRequest("inter.webs.test", dns.TypeNS)
+	expected := "/coredns/test/webs/inter/kube-system/coredns"
+
+	var svcs []msg.Service
+	k.recordsForNS(r, &svcs)
+	if svcs[0].Key != expected {
+		t.Errorf("Expected  result '%v'. Instead got result '%v'.", expected, svcs[0].Key)
+	}
+}
+
+func TestDefaultNSMsg(t *testing.T) {
+	k := Kubernetes{Zones: []string{"inter.webs.test"}}
+	corednsRecord.Hdr.Name = "coredns.kube-system."
+	corednsRecord.A = net.IP("1.2.3.4")
+	r, _ := k.parseRequest("ns.dns.inter.webs.test", dns.TypeA)
+	expected := "/coredns/test/webs/inter/dns/ns"
+
+	svc := k.defaultNSMsg(r)
+	if svc.Key != expected {
+		t.Errorf("Expected  result '%v'. Instead got result '%v'.", expected, svc.Key)
+	}
+}
+
+func TestIsDefaultNS(t *testing.T) {
+	k := Kubernetes{Zones: []string{"inter.webs.test"}}
+	r, _ := k.parseRequest("ns.dns.inter.webs.test", dns.TypeA)
+
+	var name string
+	var expected bool
+
+	name = "ns.dns.inter.webs.test"
+	expected = true
+	if isDefaultNS(name, r) != expected {
+		t.Errorf("Expected IsDefaultNS('%v') to be '%v'.", name, expected)
+	}
+	name = "ns.dns.blah.inter.webs.test"
+	expected = false
+	if isDefaultNS(name, r) != expected {
+		t.Errorf("Expected IsDefaultNS('%v') to be '%v'.", name, expected)
+	}
+}
+
+type APIConnTest struct{}
+
+func (APIConnTest) Run() {
+	return
+}
+
+func (APIConnTest) Stop() error {
+	return nil
+}
+
+func (APIConnTest) ServiceList() []*api.Service {
+	svc := api.Service{
+		ObjectMeta: api.ObjectMeta{
+			Name:      "dns-service",
+			Namespace: "kube-system",
+		},
+		Spec: api.ServiceSpec{
+			ClusterIP: "10.0.0.111",
+		},
+	}
+
+	return []*api.Service{&svc}
+
+}
+
+func (APIConnTest) PodIndex(string) []interface{} {
+	return nil
+}
+
+func (APIConnTest) EndpointsList() api.EndpointsList {
+	return api.EndpointsList{
+		Items: []api.Endpoints{
+			{
+				Subsets: []api.EndpointSubset{
+					{
+						Addresses: []api.EndpointAddress{
+							{
+								IP: "172.0.40.10",
+							},
+						},
+					},
+				},
+				ObjectMeta: api.ObjectMeta{
+					Name:      "dns-service",
+					Namespace: "kube-system",
+				},
+			},
+		},
+	}
+}
+
+type InterfaceAddrsTest struct{}
+
+func (i InterfaceAddrsTest) InterfaceAddrs() ([]net.Addr, error) {
+	_, ipnet, _ := net.ParseCIDR("172.0.40.10/32")
+	return []net.Addr{ipnet}, nil
+}
+
+func TestDoCoreDNSRecord(t *testing.T) {
+
+	corednsRecord = dns.A{}
+	k := Kubernetes{Zones: []string{"inter.webs.test"}}
+
+	k.interfaceAddrs = &InterfaceAddrsTest{}
+	k.APIConn = &APIConnTest{}
+
+	cdr := k.CoreDNSRecord()
+
+	expected := "10.0.0.111"
+
+	if cdr.A.String() != expected {
+		t.Errorf("Expected A to be '%v', got '%v'", expected, cdr.A.String())
+	}
+	expected = "dns-service.kube-system.svc."
+	if cdr.Hdr.Name != expected {
+		t.Errorf("Expected Hdr.Name to be '%v', got '%v'", expected, cdr.Hdr.Name)
+	}
+}