Add alias annotation for ingress

provider/aws.go

@@ -364,6 +364,11 @@ func (p *AWSProvider) newChange(action string, endpoint *endpoint.Endpoint) *rou
 		},
 	}
 
+	rec, err := p.Records()
+	if err != nil {
+		log.Errorf("getting records failed: %v", err)
+	}
+
 	if isAWSLoadBalancer(endpoint) {
 		evalTargetHealth := p.evaluateTargetHealth
 		if _, ok := endpoint.ProviderSpecific[providerSpecificEvaluateTargetHealth]; ok {
@@ -376,6 +381,20 @@ func (p *AWSProvider) newChange(action string, endpoint *endpoint.Endpoint) *rou
 			HostedZoneId:         aws.String(canonicalHostedZone(endpoint.Targets[0])),
 			EvaluateTargetHealth: aws.Bool(evalTargetHealth),
 		}
+	} else if hostedZone := isAWSAlias(endpoint, rec); hostedZone != "" {
+		//FIXME should break if err != nil
+		zones, err := p.Zones()
+		if err != nil {
+			log.Errorf("getting zones failed: %v", err)
+		}
+		for _, zone := range zones {
+			change.ResourceRecordSet.Type = aws.String(route53.RRTypeA)
+			change.ResourceRecordSet.AliasTarget = &route53.AliasTarget{
+				DNSName:              aws.String(endpoint.Targets[0]),
+				HostedZoneId:         aws.String(cleanZoneID(*zone.Id)),
+				EvaluateTargetHealth: aws.Bool(p.evaluateTargetHealth),
+			}
+		}
 	} else {
 		change.ResourceRecordSet.Type = aws.String(endpoint.RecordType)
 		if !endpoint.RecordTTL.IsConfigured() {
@@ -529,6 +548,21 @@ func isAWSLoadBalancer(ep *endpoint.Endpoint) bool {
 	return false
 }
 
+// isAWSAlias determines if a given hostname belongs to an AWS Alias record by doing an reverse lookup.
+func isAWSAlias(ep *endpoint.Endpoint, addrs []*endpoint.Endpoint) string {
+	if val, exists := ep.ProviderSpecific["alias"]; ep.RecordType == endpoint.RecordTypeCNAME && exists && val == "true" {
+		for _, addr := range addrs {
+			if addr.DNSName == ep.Targets[0] {
+				if hostedZone := canonicalHostedZone(addr.Targets[0]); hostedZone != "" {
+					return hostedZone
+				}
+
+			}
+		}
+	}
+	return ""
+}
+
 // canonicalHostedZone returns the matching canonical zone for a given hostname.
 func canonicalHostedZone(hostname string) string {
 	for suffix, zone := range canonicalHostedZones {
@@ -539,3 +573,11 @@ func canonicalHostedZone(hostname string) string {
 
 	return ""
 }
+
+// cleanZoneID removes the "/hostedzone/" prefix
+func cleanZoneID(ID string) string {
+	if strings.HasPrefix(ID, "/hostedzone/") {
+		ID = strings.TrimPrefix(ID, "/hostedzone/")
+	}
+	return ID
+}

provider/aws_test.go

@@ -819,6 +819,35 @@ func TestAWSisLoadBalancer(t *testing.T) {
 	}
 }
 
+func TestAWSisAWSAlias(t *testing.T) {
+	for _, tc := range []struct {
+		target     string
+		recordType string
+		alias      string
+		expected   string
+	}{
+		{"bar.example.org", endpoint.RecordTypeCNAME, "true", "Z215JYRZR1TBD5"},
+		{"foo.example.org", endpoint.RecordTypeCNAME, "true", ""},
+	} {
+		ep := &endpoint.Endpoint{
+			Targets:          endpoint.Targets{tc.target},
+			RecordType:       tc.recordType,
+			ProviderSpecific: map[string]string{"alias": tc.alias},
+		}
+		addrs := []*endpoint.Endpoint{
+			&endpoint.Endpoint{
+				DNSName: "foo.example.org",
+				Targets: endpoint.Targets{"foobar.example.org"},
+			},
+			&endpoint.Endpoint{
+				DNSName: "bar.example.org",
+				Targets: endpoint.Targets{"bar.eu-central-1.elb.amazonaws.com"},
+			},
+		}
+		assert.Equal(t, tc.expected, isAWSAlias(ep, addrs))
+	}
+}
+
 func TestAWSCanonicalHostedZone(t *testing.T) {
 	for _, tc := range []struct {
 		hostname string

source/gateway.go

@@ -172,12 +172,14 @@ func (sc *gatewaySource) endpointsFromTemplate(config *istiomodel.Config) ([]*en
 		}
 	}
 
+	providerSpecific := getProviderSpecificAnnotations(config.Annotations)
+
 	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)...)
+		endpoints = append(endpoints, endpointsForHostname(hostname, targets, ttl, providerSpecific)...)
 	}
 	return endpoints, nil
 }
@@ -256,18 +258,20 @@ func (sc *gatewaySource) endpointsFromGatewayConfig(config istiomodel.Config) ([
 
 	gateway := config.Spec.(*istionetworking.Gateway)
 
+	providerSpecific := getProviderSpecificAnnotations(config.Annotations)
+
 	for _, server := range gateway.Servers {
 		for _, host := range server.Hosts {
 			if host == "" {
 				continue
 			}
-			endpoints = append(endpoints, endpointsForHostname(host, targets, ttl)...)
+			endpoints = append(endpoints, endpointsForHostname(host, targets, ttl, providerSpecific)...)
 		}
 	}
 
 	hostnameList := getHostnamesFromAnnotations(config.Annotations)
 	for _, hostname := range hostnameList {
-		endpoints = append(endpoints, endpointsForHostname(hostname, targets, ttl)...)
+		endpoints = append(endpoints, endpointsForHostname(hostname, targets, ttl, providerSpecific)...)
 	}
 
 	return endpoints, nil

source/ingress.go

@@ -146,12 +146,14 @@ func (sc *ingressSource) endpointsFromTemplate(ing *v1beta1.Ingress) ([]*endpoin
 		targets = targetsFromIngressStatus(ing.Status)
 	}
 
+	providerSpecific := getProviderSpecificAnnotations(ing.Annotations)
+
 	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)...)
+		endpoints = append(endpoints, endpointsForHostname(hostname, targets, ttl, providerSpecific)...)
 	}
 	return endpoints, nil
 }
@@ -208,11 +210,13 @@ func endpointsFromIngress(ing *v1beta1.Ingress) []*endpoint.Endpoint {
 		targets = targetsFromIngressStatus(ing.Status)
 	}
 
+	providerSpecific := getProviderSpecificAnnotations(ing.Annotations)
+
 	for _, rule := range ing.Spec.Rules {
 		if rule.Host == "" {
 			continue
 		}
-		endpoints = append(endpoints, endpointsForHostname(rule.Host, targets, ttl)...)
+		endpoints = append(endpoints, endpointsForHostname(rule.Host, targets, ttl, providerSpecific)...)
 	}
 
 	for _, tls := range ing.Spec.TLS {
@@ -220,13 +224,13 @@ func endpointsFromIngress(ing *v1beta1.Ingress) []*endpoint.Endpoint {
 			if host == "" {
 				continue
 			}
-			endpoints = append(endpoints, endpointsForHostname(host, targets, ttl)...)
+			endpoints = append(endpoints, endpointsForHostname(host, targets, ttl, providerSpecific)...)
 		}
 	}
 
 	hostnameList := getHostnamesFromAnnotations(ing.Annotations)
 	for _, hostname := range hostnameList {
-		endpoints = append(endpoints, endpointsForHostname(hostname, targets, ttl)...)
+		endpoints = append(endpoints, endpointsForHostname(hostname, targets, ttl, providerSpecific)...)
 	}
 
 	return endpoints

source/ingress_test.go

@@ -817,6 +817,52 @@ func testIngressEndpoints(t *testing.T) {
 				},
 			},
 		},
+		{
+			title:           "ingress rules with alias and target annotation",
+			targetNamespace: "",
+			ingressItems: []fakeIngress{
+				{
+					name:      "fake1",
+					namespace: namespace,
+					annotations: map[string]string{
+						targetAnnotationKey: "ingress-target.com",
+						aliasAnnotationKey:  "true",
+					},
+					dnsnames: []string{"example.org"},
+					ips:      []string{},
+				},
+			},
+			expected: []*endpoint.Endpoint{
+				{
+					DNSName:    "example.org",
+					Targets:    endpoint.Targets{"ingress-target.com"},
+					RecordType: endpoint.RecordTypeCNAME,
+				},
+			},
+		},
+		{
+			title:           "ingress rules with alias set false and target annotation",
+			targetNamespace: "",
+			ingressItems: []fakeIngress{
+				{
+					name:      "fake1",
+					namespace: namespace,
+					annotations: map[string]string{
+						targetAnnotationKey: "ingress-target.com",
+						aliasAnnotationKey:  "false",
+					},
+					dnsnames: []string{"example.org"},
+					ips:      []string{},
+				},
+			},
+			expected: []*endpoint.Endpoint{
+				{
+					DNSName:    "example.org",
+					Targets:    endpoint.Targets{"ingress-target.com"},
+					RecordType: endpoint.RecordTypeCNAME,
+				},
+			},
+		},
 		{
 			title:           "template for ingress with annotation",
 			targetNamespace: "",

source/source.go

@@ -35,6 +35,8 @@ const (
 	targetAnnotationKey = "external-dns.alpha.kubernetes.io/target"
 	// The annotation used for defining the desired DNS record TTL
 	ttlAnnotationKey = "external-dns.alpha.kubernetes.io/ttl"
+	//// The annotation used for switching to the alias record types e. g. AWS Alias records instead of a normal CNAME
+	aliasAnnotationKey = "external-dns.alpha.kubernetes.io/alias"
 	// The value of the controller annotation so that we feel responsible
 	controllerAnnotationValue = "dns-controller"
 )
@@ -74,6 +76,18 @@ func getHostnamesFromAnnotations(annotations map[string]string) []string {
 	return strings.Split(strings.Replace(hostnameAnnotation, " ", "", -1), ",")
 }
 
+func getAliasFromAnnotations(annotations map[string]string) bool {
+	aliasAnnotation, exists := annotations[aliasAnnotationKey]
+	return exists && aliasAnnotation == "true"
+}
+
+func getProviderSpecificAnnotations(annotations map[string]string) endpoint.ProviderSpecific {
+	if getAliasFromAnnotations(annotations) {
+		return map[string]string{"alias": "true"}
+	}
+	return map[string]string{}
+}
+
 // getTargetsFromTargetAnnotation gets endpoints from optional "target" annotation.
 // Returns empty endpoints array if none are found.
 func getTargetsFromTargetAnnotation(annotations map[string]string) endpoint.Targets {
@@ -102,7 +116,7 @@ func suitableType(target string) string {
 }
 
 // endpointsForHostname returns the endpoint objects for each host-target combination.
-func endpointsForHostname(hostname string, targets endpoint.Targets, ttl endpoint.TTL) []*endpoint.Endpoint {
+func endpointsForHostname(hostname string, targets endpoint.Targets, ttl endpoint.TTL, providerSpecific endpoint.ProviderSpecific) []*endpoint.Endpoint {
 	var endpoints []*endpoint.Endpoint
 
 	var aTargets endpoint.Targets
@@ -124,6 +138,7 @@ func endpointsForHostname(hostname string, targets endpoint.Targets, ttl endpoin
 			RecordTTL:        ttl,
 			RecordType:       endpoint.RecordTypeA,
 			Labels:           endpoint.NewLabels(),
+			ProviderSpecific: providerSpecific,
 		}
 		endpoints = append(endpoints, epA)
 	}
@@ -135,6 +150,7 @@ func endpointsForHostname(hostname string, targets endpoint.Targets, ttl endpoin
 			RecordTTL:        ttl,
 			RecordType:       endpoint.RecordTypeCNAME,
 			Labels:           endpoint.NewLabels(),
+			ProviderSpecific: providerSpecific,
 		}
 		endpoints = append(endpoints, epCNAME)
 	}