Support a comma separated list for the FQDN template (#512)

* Support a comma separated list for the FQDN template

* Add documentation for comma separated FQDN templates

* chore: add multiple fqdn templates to changelog

CHANGELOG.md

@@ -1,3 +1,4 @@
+  - Support a comma separated list for the FQDN template (#512) @helgi
   - Google Provider: Add auto-detection of Google Project when running on GCP (#492) @drzero42
   - Add custom TTL support for DNSimple (#477) @jbowes
   - Fix docker build and delete vendor files which were not deleted (#473) @njuettner

docs/faq.md

@@ -48,6 +48,10 @@ There are three sources of information for ExternalDNS to decide on DNS name. Ex
 
 3. If `--fqdn-template` flag is specified, e.g. `--fqdn-template={{.Name}}.my-org.com`, ExternalDNS will use service/ingress specifications for the provided template to generate DNS name.
 
+### Can I specify multiple global FQDN templates?
+
+Yes, yes you can. Pass in a comma separated list to `--fqdn-template`. Beaware this will double (triple, etc) the amount of DNS entries based on how many services, ingresses and so on you have and will get you faster towards the API request limit of your DNS provider.
+
 ### Which Service and Ingress controllers are supported?
 
 Regarding Services, we'll support the OSI Layer 4 load balancers that Kubernetes creates on AWS and Google Container Engine, and possibly other clusters running on Google Compute Engine.

pkg/apis/externaldns/types.go

@@ -151,7 +151,7 @@ func (cfg *Config) ParseFlags(args []string) error {
 	app.Flag("source", "The resource types that are queried for endpoints; specify multiple times for multiple sources (required, options: service, ingress, fake)").Required().PlaceHolder("source").EnumsVar(&cfg.Sources, "service", "ingress", "fake")
 	app.Flag("namespace", "Limit sources of endpoints to a specific namespace (default: all namespaces)").Default(defaultConfig.Namespace).StringVar(&cfg.Namespace)
 	app.Flag("annotation-filter", "Filter sources managed by external-dns via annotation using label selector semantics (default: all sources)").Default(defaultConfig.AnnotationFilter).StringVar(&cfg.AnnotationFilter)
-	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("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). Accepts comma separated list for multiple global FQDN.").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)
 

source/ingress.go

@@ -136,14 +136,14 @@ func getTargetsFromTargetAnnotation(ing *v1beta1.Ingress) endpoint.Targets {
 }
 
 func (sc *ingressSource) endpointsFromTemplate(ing *v1beta1.Ingress) ([]*endpoint.Endpoint, error) {
-
+	// Process the whole template string
 	var buf bytes.Buffer
 	err := sc.fqdnTemplate.Execute(&buf, ing)
 	if err != nil {
 		return nil, fmt.Errorf("failed to apply template on ingress %s: %v", ing.String(), err)
 	}
 
-	hostname := buf.String()
+	hostnames := buf.String()
 
 	ttl, err := getTTLFromAnnotations(ing.Annotations)
 	if err != nil {
@@ -156,7 +156,14 @@ func (sc *ingressSource) endpointsFromTemplate(ing *v1beta1.Ingress) ([]*endpoin
 		targets = targetsFromIngressStatus(ing.Status)
 	}
 
-	return endpointsForHostname(hostname, targets, ttl), nil
+	var endpoints []*endpoint.Endpoint
+	// splits the FQDN template and removes the trailing periods
+	hostnameList := strings.Split(strings.Replace(hostnames, " ", "", -1), ",")
+	for _, hostname := range hostnameList {
+		hostname = strings.TrimSuffix(hostname, ".")
+		endpoints = append(endpoints, endpointsForHostname(hostname, targets, ttl)...)
+	}
+	return endpoints, nil
 }
 
 // filterByAnnotations filters a list of ingresses by a given annotation selector.

source/ingress_test.go

@@ -473,6 +473,32 @@ func testIngressEndpoints(t *testing.T) {
 			expected:     []*endpoint.Endpoint{},
 			fqdnTemplate: "{{.Name}}.ext-dns.test.com",
 		},
+		{
+			title:           "multiple FQDN template hostnames",
+			targetNamespace: "",
+			ingressItems: []fakeIngress{
+				{
+					name:        "fake1",
+					namespace:   namespace,
+					annotations: map[string]string{},
+					dnsnames:    []string{},
+					ips:         []string{"8.8.8.8"},
+				},
+			},
+			expected: []*endpoint.Endpoint{
+				{
+					DNSName:    "fake1.ext-dns.test.com",
+					Targets:    endpoint.Targets{"8.8.8.8"},
+					RecordType: endpoint.RecordTypeA,
+				},
+				{
+					DNSName:    "fake1.ext-dna.test.com",
+					Targets:    endpoint.Targets{"8.8.8.8"},
+					RecordType: endpoint.RecordTypeA,
+				},
+			},
+			fqdnTemplate: "{{.Name}}.ext-dns.test.com, {{.Name}}.ext-dna.test.com",
+		},
 		{
 			title:           "ingress rules with annotation",
 			targetNamespace: "",

source/service.go

@@ -162,15 +162,17 @@ func (sc *serviceSource) extractHeadlessEndpoints(svc *v1.Service, hostname stri
 func (sc *serviceSource) endpointsFromTemplate(svc *v1.Service) ([]*endpoint.Endpoint, error) {
 	var endpoints []*endpoint.Endpoint
 
+	// Process the whole template string
 	var buf bytes.Buffer
 	err := sc.fqdnTemplate.Execute(&buf, svc)
 	if err != nil {
 		return nil, fmt.Errorf("failed to apply template on service %s: %v", svc.String(), err)
 	}
 
-	hostname := buf.String()
-
-	endpoints = sc.generateEndpoints(svc, hostname)
+	hostnameList := strings.Split(strings.Replace(buf.String(), " ", "", -1), ",")
+	for _, hostname := range hostnameList {
+		endpoints = append(endpoints, sc.generateEndpoints(svc, hostname)...)
+	}
 
 	return endpoints, nil
 }

source/service_test.go

@@ -213,6 +213,25 @@ func testServiceSourceEndpoints(t *testing.T) {
 			[]*endpoint.Endpoint{},
 			false,
 		},
+		{
+			"FQDN template with multiple hostnames return an endpoint with target IP",
+			"",
+			"",
+			"testing",
+			"foo",
+			v1.ServiceTypeLoadBalancer,
+			"",
+			"{{.Name}}.fqdn.org,{{.Name}}.fqdn.com",
+			map[string]string{},
+			map[string]string{},
+			"",
+			[]string{"1.2.3.4"},
+			[]*endpoint.Endpoint{
+				{DNSName: "foo.fqdn.org", Targets: endpoint.Targets{"1.2.3.4"}},
+				{DNSName: "foo.fqdn.com", Targets: endpoint.Targets{"1.2.3.4"}},
+			},
+			false,
+		},
 		{
 			"annotated services with multiple hostnames return an endpoint with target IP",
 			"",