ClusterIp Service support (kubernetes-sigs#278)

* ClusterIP service support

- First pass at addresssing kubernetes-sigs#187 by allowing services with type ClusterIP to be directly supported

* Getting existing tests to pass

* Adjusting formatting for gofmt/govet

* Adding in guard logic around publishing of ClusterIP sources

* Addressing PR feedback

* Adding in CHANGELOG entry

* Adding in Headless service test

.gitignore

@@ -42,3 +42,4 @@ cscope.*
 # coverage output
 cover.out
 *.coverprofile
+external-dns

CHANGELOG.md

@@ -1,6 +1,9 @@
+  - ExternalDNS now services of type `ClusterIP` with the use of the `--publish-internal-services`.  Enabling this will now create the apprioriate A records for the given service's internal ip.  @jrnt30
+
 ## v0.4.3 - 2017-08-17
 
   - Fix to have external target annotations on ingress resources replace existing endpoints instead of appending to them (#318)
+
 ## v0.4.2 - 2017-08-03
 
   - Fix to support multiple hostnames for Molecule Software's [route53-kubernetes](https://github.com/wearemolecule/route53-kubernetes) compatibility (#301)

main.go

@@ -65,9 +65,10 @@ func main() {
 
 	// Create a source.Config from the flags passed by the user.
 	sourceCfg := &source.Config{
-		Namespace:     cfg.Namespace,
-		FQDNTemplate:  cfg.FQDNTemplate,
-		Compatibility: cfg.Compatibility,
+		Namespace:       cfg.Namespace,
+		FQDNTemplate:    cfg.FQDNTemplate,
+		Compatibility:   cfg.Compatibility,
+		PublishInternal: cfg.PublishInternal,
 	}
 
 	// Lookup all the selected sources by names and pass them the desired configuration.

pkg/apis/externaldns/types.go

@@ -34,6 +34,7 @@ type Config struct {
 	Namespace          string
 	FQDNTemplate       string
 	Compatibility      string
+	PublishInternal    bool
 	Provider           string
 	GoogleProject      string
 	DomainFilter       []string
@@ -58,6 +59,7 @@ var defaultConfig = &Config{
 	Namespace:          "",
 	FQDNTemplate:       "",
 	Compatibility:      "",
+	PublishInternal:    false,
 	Provider:           "",
 	GoogleProject:      "",
 	DomainFilter:       []string{},
@@ -95,6 +97,7 @@ func (cfg *Config) ParseFlags(args []string) error {
 	app.Flag("namespace", "Limit sources of endpoints to a specific namespace (default: all namespaces)").Default(defaultConfig.Namespace).StringVar(&cfg.Namespace)
 	app.Flag("fqdn-template", "A templated string that's used to generate DNS names from sources that don't define a hostname themselves, or to add a hostname suffix when paired with the fake source (optional)").Default(defaultConfig.FQDNTemplate).StringVar(&cfg.FQDNTemplate)
 	app.Flag("compatibility", "Process annotation semantics from legacy implementations (optional, options: mate, molecule)").Default(defaultConfig.Compatibility).EnumVar(&cfg.Compatibility, "", "mate", "molecule")
+	app.Flag("publish-internal-services", "Allow external-dns to publish DNS records for ClusterIP services (optional)").BoolVar(&cfg.PublishInternal)
 
 	// Flags related to providers
 	app.Flag("provider", "The DNS provider where the DNS records will be created (required, options: aws, google, azure, cloudflare, digitalocean, inmemory)").Required().PlaceHolder("provider").EnumVar(&cfg.Provider, "aws", "google", "azure", "cloudflare", "digitalocean", "inmemory")

source/service.go

@@ -34,18 +34,19 @@ import (
 // serviceSource is an implementation of Source for Kubernetes service objects.
 // It will find all services that are under our jurisdiction, i.e. annotated
 // desired hostname and matching or no controller annotation. For each of the
-// matched services' external entrypoints it will return a corresponding
+// matched services' entrypoints it will return a corresponding
 // Endpoint object.
 type serviceSource struct {
 	client    kubernetes.Interface
 	namespace string
 	// process Services with legacy annotations
-	compatibility string
-	fqdnTemplate  *template.Template
+	compatibility   string
+	fqdnTemplate    *template.Template
+	publishInternal bool
 }
 
 // NewServiceSource creates a new serviceSource with the given config.
-func NewServiceSource(kubeClient kubernetes.Interface, namespace, fqdnTemplate, compatibility string) (Source, error) {
+func NewServiceSource(kubeClient kubernetes.Interface, namespace, fqdnTemplate, compatibility string, publishInternal bool) (Source, error) {
 	var (
 		tmpl *template.Template
 		err  error
@@ -60,10 +61,11 @@ func NewServiceSource(kubeClient kubernetes.Interface, namespace, fqdnTemplate,
 	}
 
 	return &serviceSource{
-		client:        kubeClient,
-		namespace:     namespace,
-		compatibility: compatibility,
-		fqdnTemplate:  tmpl,
+		client:          kubeClient,
+		namespace:       namespace,
+		compatibility:   compatibility,
+		fqdnTemplate:    tmpl,
+		publishInternal: publishInternal,
 	}, nil
 }
 
@@ -85,7 +87,7 @@ func (sc *serviceSource) Endpoints() ([]*endpoint.Endpoint, error) {
 			continue
 		}
 
-		svcEndpoints := endpointsFromService(&svc)
+		svcEndpoints := sc.endpoints(&svc)
 
 		// process legacy annotations if no endpoints were returned and compatibility mode is enabled.
 		if len(svcEndpoints) == 0 && sc.compatibility != "" {
@@ -122,21 +124,13 @@ func (sc *serviceSource) endpointsFromTemplate(svc *v1.Service) ([]*endpoint.End
 	}
 
 	hostname := buf.String()
-	for _, lb := range svc.Status.LoadBalancer.Ingress {
-		if lb.IP != "" {
-			//TODO(ideahitme): consider retrieving record type from resource annotation instead of empty
-			endpoints = append(endpoints, endpoint.NewEndpoint(hostname, lb.IP, ""))
-		}
-		if lb.Hostname != "" {
-			endpoints = append(endpoints, endpoint.NewEndpoint(hostname, lb.Hostname, ""))
-		}
-	}
+	endpoints = sc.generateEndpoints(svc, hostname)
 
 	return endpoints, nil
 }
 
 // endpointsFromService extracts the endpoints from a service object
-func endpointsFromService(svc *v1.Service) []*endpoint.Endpoint {
+func (sc *serviceSource) endpoints(svc *v1.Service) []*endpoint.Endpoint {
 	var endpoints []*endpoint.Endpoint
 
 	// Get the desired hostname of the service from the annotation.
@@ -145,20 +139,50 @@ func endpointsFromService(svc *v1.Service) []*endpoint.Endpoint {
 		return nil
 	}
 
-	// splits the hostname annotation and removes the trailing periods
 	hostnameList := strings.Split(strings.Replace(hostnameAnnotation, " ", "", -1), ",")
-
 	for _, hostname := range hostnameList {
-		hostname = strings.TrimSuffix(hostname, ".")
-		// Create a corresponding endpoint for each configured external entrypoint.
-		for _, lb := range svc.Status.LoadBalancer.Ingress {
-			if lb.IP != "" {
-				//TODO(ideahitme): consider retrieving record type from resource annotation instead of empty
-				endpoints = append(endpoints, endpoint.NewEndpoint(hostname, lb.IP, ""))
-			}
-			if lb.Hostname != "" {
-				endpoints = append(endpoints, endpoint.NewEndpoint(hostname, lb.Hostname, ""))
-			}
+		endpoints = append(endpoints, sc.generateEndpoints(svc, hostname)...)
+	}
+
+	return endpoints
+}
+
+func (sc *serviceSource) generateEndpoints(svc *v1.Service, hostname string) []*endpoint.Endpoint {
+	var endpoints []*endpoint.Endpoint
+
+	hostname = strings.TrimSuffix(hostname, ".")
+	switch svc.Spec.Type {
+	case v1.ServiceTypeLoadBalancer:
+		endpoints = append(endpoints, extractLoadBalancerEndpoints(svc, hostname)...)
+	case v1.ServiceTypeClusterIP:
+		if sc.publishInternal {
+			endpoints = append(endpoints, extractServiceIps(svc, hostname)...)
+		}
+	}
+
+	return endpoints
+}
+
+func extractServiceIps(svc *v1.Service, hostname string) []*endpoint.Endpoint {
+	if svc.Spec.ClusterIP == v1.ClusterIPNone {
+		log.Debugf("Unable to associate %s headless service with a Cluster IP", svc.Name)
+		return []*endpoint.Endpoint{}
+	}
+
+	return []*endpoint.Endpoint{endpoint.NewEndpoint(hostname, svc.Spec.ClusterIP, "")}
+}
+
+func extractLoadBalancerEndpoints(svc *v1.Service, hostname string) []*endpoint.Endpoint {
+	var endpoints []*endpoint.Endpoint
+
+	// Create a corresponding endpoint for each configured external entrypoint.
+	for _, lb := range svc.Status.LoadBalancer.Ingress {
+		if lb.IP != "" {
+			//TODO(ideahitme): consider retrieving record type from resource annotation instead of empty
+			endpoints = append(endpoints, endpoint.NewEndpoint(hostname, lb.IP, ""))
+		}
+		if lb.Hostname != "" {
+			endpoints = append(endpoints, endpoint.NewEndpoint(hostname, lb.Hostname, ""))
 		}
 	}