feat: use ClusterIP with internal-hostname annotation

kubernetes-sigs · Feb 14, 2020 · b1544ac · b1544ac
1 parent b8d018f
commit b1544ac
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Showing 3 changed files with 76 additions and 9 deletions.
diff --git a/source/service.go b/source/service.go
@@ -169,7 +169,7 @@ func (sc *serviceSource) Endpoints() ([]*endpoint.Endpoint, error) {
 			continue
 		}
 
-		svcEndpoints := sc.endpoints(svc)
+		svcEndpoints := append(sc.endpoints(svc, false), sc.endpoints(svc, true)...)
 
 		// process legacy annotations if no endpoints were returned and compatibility mode is enabled.
 		if len(svcEndpoints) == 0 && sc.compatibility != "" {
@@ -178,7 +178,7 @@ func (sc *serviceSource) Endpoints() ([]*endpoint.Endpoint, error) {
 
 		// apply template if none of the above is found
 		if (sc.combineFQDNAnnotation || len(svcEndpoints) == 0) && sc.fqdnTemplate != nil {
-			sEndpoints, err := sc.endpointsFromTemplate(svc)
+			sEndpoints, err := sc.endpointsFromTemplate(svc, false)
 			if err != nil {
 				return nil, err
 			}
@@ -271,7 +271,7 @@ func (sc *serviceSource) extractHeadlessEndpoints(svc *v1.Service, hostname stri
 	return endpoints
 }
 
-func (sc *serviceSource) endpointsFromTemplate(svc *v1.Service) ([]*endpoint.Endpoint, error) {
+func (sc *serviceSource) endpointsFromTemplate(svc *v1.Service, useClusterIP bool) ([]*endpoint.Endpoint, error) {
 	var endpoints []*endpoint.Endpoint
 
 	// Process the whole template string
@@ -284,21 +284,26 @@ func (sc *serviceSource) endpointsFromTemplate(svc *v1.Service) ([]*endpoint.End
 	providerSpecific, setIdentifier := getProviderSpecificAnnotations(svc.Annotations)
 	hostnameList := strings.Split(strings.Replace(buf.String(), " ", "", -1), ",")
 	for _, hostname := range hostnameList {
-		endpoints = append(endpoints, sc.generateEndpoints(svc, hostname, providerSpecific, setIdentifier)...)
+		endpoints = append(endpoints, sc.generateEndpoints(svc, hostname, providerSpecific, setIdentifier, useClusterIP)...)
 	}
 
 	return endpoints, nil
 }
 
 // endpointsFromService extracts the endpoints from a service object
-func (sc *serviceSource) endpoints(svc *v1.Service) []*endpoint.Endpoint {
+func (sc *serviceSource) endpoints(svc *v1.Service, useClusterIP bool) []*endpoint.Endpoint {
 	var endpoints []*endpoint.Endpoint
 	// Skip endpoints if we do not want entries from annotations
 	if !sc.ignoreHostnameAnnotation {
 		providerSpecific, setIdentifier := getProviderSpecificAnnotations(svc.Annotations)
-		hostnameList := getHostnamesFromAnnotations(svc.Annotations)
+		var hostnameList []string
+		if useClusterIP {
+			hostnameList = getInternalHostnamesFromAnnotations(svc.Annotations)
+		} else {
+			hostnameList = getHostnamesFromAnnotations(svc.Annotations)
+		}
 		for _, hostname := range hostnameList {
-			endpoints = append(endpoints, sc.generateEndpoints(svc, hostname, providerSpecific, setIdentifier)...)
+			endpoints = append(endpoints, sc.generateEndpoints(svc, hostname, providerSpecific, setIdentifier, useClusterIP)...)
 		}
 	}
 	return endpoints
@@ -354,7 +359,7 @@ func (sc *serviceSource) setResourceLabel(service *v1.Service, endpoints []*endp
 	}
 }
 
-func (sc *serviceSource) generateEndpoints(svc *v1.Service, hostname string, providerSpecific endpoint.ProviderSpecific, setIdentifier string) []*endpoint.Endpoint {
+func (sc *serviceSource) generateEndpoints(svc *v1.Service, hostname string, providerSpecific endpoint.ProviderSpecific, setIdentifier string, useClusterIP bool) []*endpoint.Endpoint {
 	hostname = strings.TrimSuffix(hostname, ".")
 	ttl, err := getTTLFromAnnotations(svc.Annotations)
 	if err != nil {
@@ -382,7 +387,11 @@ func (sc *serviceSource) generateEndpoints(svc *v1.Service, hostname string, pro
 
 	switch svc.Spec.Type {
 	case v1.ServiceTypeLoadBalancer:
-		targets = append(targets, extractLoadBalancerTargets(svc)...)
+		if useClusterIP {
+			targets = append(targets, extractServiceIps(svc)...)
+		} else {
+			targets = append(targets, extractLoadBalancerTargets(svc)...)
+		}
 	case v1.ServiceTypeClusterIP:
 		if sc.publishInternal {
 			targets = append(targets, extractServiceIps(svc)...)

diff --git a/source/service_test.go b/source/service_test.go
@@ -1061,6 +1061,54 @@ func testServiceSourceEndpoints(t *testing.T) {
 			[]*endpoint.Endpoint{},
 			false,
 		},
+		{
+			"internal-host annotated services return an endpoint with Cluster IP",
+			"",
+			"",
+			"testing",
+			"foo",
+			v1.ServiceTypeLoadBalancer,
+			"",
+			"",
+			false,
+			false,
+			map[string]string{},
+			map[string]string{
+				internalHostnameAnnotationKey: "foo.internal.example.org.",
+			},
+			"1.1.1.1",
+			[]string{"1.2.3.4"},
+                        []string{},
+			[]*endpoint.Endpoint{
+                                {DNSName: "foo.internal.example.org", Targets: endpoint.Targets{"1.1.1.1"}},
+			},
+			false,
+		},
+		{
+			"internal-host annotated and host annotated services return an endpoint with Cluster IP and an endpoint with lb IP",
+			"",
+			"",
+			"testing",
+			"foo",
+			v1.ServiceTypeLoadBalancer,
+			"",
+			"",
+			false,
+			false,
+			map[string]string{},
+			map[string]string{
+				hostnameAnnotationKey: "foo.example.org.",
+				internalHostnameAnnotationKey: "foo.internal.example.org.",
+			},
+			"1.1.1.1",
+			[]string{"1.2.3.4"},
+                        []string{},
+			[]*endpoint.Endpoint{
+                                {DNSName: "foo.internal.example.org", Targets: endpoint.Targets{"1.1.1.1"}},
+                                {DNSName: "foo.example.org", Targets: endpoint.Targets{"1.2.3.4"}},
+			},
+			false,
+		},
 	} {
 		t.Run(tc.title, func(t *testing.T) {
 			// Create a Kubernetes testing client

diff --git a/source/source.go b/source/source.go
@@ -40,6 +40,8 @@ const (
 	aliasAnnotationKey = "external-dns.alpha.kubernetes.io/alias"
 	// The value of the controller annotation so that we feel responsible
 	controllerAnnotationValue = "dns-controller"
+        // The annotation used for defining the desired hostname
+        internalHostnameAnnotationKey = "external-dns.alpha.kubernetes.io/internal-hostname"
 )
 
 // Provider-specific annotations
@@ -102,6 +104,14 @@ func getHostnamesFromAnnotations(annotations map[string]string) []string {
 	return strings.Split(strings.Replace(hostnameAnnotation, " ", "", -1), ",")
 }
 
+func getInternalHostnamesFromAnnotations(annotations map[string]string) []string {
+        internalHostnameAnnotation, exists := annotations[internalHostnameAnnotationKey]
+        if !exists {
+                return nil
+        }
+        return strings.Split(strings.Replace(internalHostnameAnnotation, " ", "", -1), ",")
+}
+
 func getAliasFromAnnotations(annotations map[string]string) bool {
 	aliasAnnotation, exists := annotations[aliasAnnotationKey]
 	return exists && aliasAnnotation == "true"