support hostnames as endpoint targets (CNAME support) (#122)

* feat(aws): support hostnames as endpoint targets

* docs: describe how to run ExternalDNS on AWS

* docs: update changelog with CNAME feature

* docs: update changelog to include AWS documentation

* fix(aws): test that updating records removes the old value

* feat(google): add CNAME support to Google provider

* fix(source): sanitize source and target hostnames

* docs: update changelog to include latest changes

* docs(aws): mention that ExternalDNS takes full ownership of a hosted zone

* fix(aws): switch route53 tests to use endpoint pointers

* docs: add TODO to remove record filtering once ownership is in place

CHANGELOG.md

+Features:
+
+  - Support creation of CNAME records when endpoint target is a hostname.
+  - Allow omitting the trailing dot in Service annotations.
+
 Bug fixes:
 
   - AWS Route 53: Do not submit request when there are no changes.
 
+Documentation:
+
+  - Add documentation on how to setup ExternalDNS for Services on AWS.
+
 ## v0.1.0 - 2017-03-30 (KubeCon)
 
 Features:

README.md

@@ -42,7 +42,7 @@ $ kubectl run nginx --image=nginx --replicas=1 --port=80
 $ kubectl expose deployment nginx --port=80 --target-port=80 --type=LoadBalancer
 ```
 
-Annotate the Service with your desired external DNS name. Make sure to change `example.org` to your domain (and that it includes the trailing dot):
+Annotate the Service with your desired external DNS name. Make sure to change `example.org` to your domain.
 
 ```console
 $ kubectl annotate service nginx "external-dns.alpha.kubernetes.io/hostname=nginx.example.org."

docs/tutorials/aws.md

+# Setting up ExternalDNS for Services on AWS
+
+This tutorial describes how to setup ExternalDNS for usage within a Kubernetes cluster on AWS.
+
+Create a DNS zone which will contain the managed DNS records.
+
+```console
+$ aws route53 create-hosted-zone --name "external-dns-test.teapot.zalan.do." --caller-reference "external-dns-test-$(date +%s)"
+```
+
+Make a note of the ID of the hosted zone you just created.
+
+```console
+$ aws route53 list-hosted-zones-by-name --dns-name "external-dns-test.teapot.zalan.do." | jq -r '.HostedZones[0].Id'
+/hostedzone/Z16P7IEWFWZ4RB
+```
+
+Make a note of the nameservers that were assigned to your new zone.
+
+```console
+$ aws route53 list-resource-record-sets --hosted-zone-id "/hostedzone/Z16P7IEWFWZ4RB" \
+    --query "ResourceRecordSets[?Type == 'NS']" | jq -r '.[0].ResourceRecords[].Value'
+ns-1455.awsdns-53.org.
+ns-1694.awsdns-19.co.uk.
+ns-764.awsdns-31.net.
+ns-62.awsdns-07.com.
+```
+
+In this case it's the ones shown above but your's will differ.
+
+If you decide not to create a new zone but reuse an existing one, make sure it's currently **unused** and **empty**. This version of ExternalDNS will remove all records it doesn't recognize from the zone.
+
+Connect your `kubectl` client to the cluster you want to test ExternalDNS with.
+Then apply the following manifest file to deploy ExternalDNS.
+
+```yaml
+apiVersion: extensions/v1beta1
+kind: Deployment
+metadata:
+  name: external-dns
+spec:
+  strategy:
+    type: Recreate
+  template:
+    metadata:
+      labels:
+        app: external-dns
+    spec:
+      containers:
+      - name: external-dns
+        image: registry.opensource.zalan.do/teapot/external-dns:v0.2.0-beta.0
+        args:
+        - --in-cluster
+        - --zone=external-dns-test.teapot.zalan.do.
+        - --source=service
+        - --provider=aws
+        - --dry-run=false
+```
+
+Create the following sample application to test that ExternalDNS works.
+
+```yaml
+apiVersion: v1
+kind: Service
+metadata:
+  name: nginx
+  annotations:
+    external-dns.alpha.kubernetes.io/hostname: nginx.external-dns-test.teapot.zalan.do.
+spec:
+  type: LoadBalancer
+  ports:
+  - port: 80
+    targetPort: 80
+  selector:
+    app: nginx
+
+---
+
+apiVersion: extensions/v1beta1
+kind: Deployment
+metadata:
+  name: nginx
+spec:
+  template:
+    metadata:
+      labels:
+        app: nginx
+    spec:
+      containers:
+      - image: nginx
+        name: nginx
+        ports:
+        - containerPort: 80
+```
+
+After roughly two minutes check that a corresponding DNS record for your service was created.
+
+```console
+$ aws route53 list-resource-record-sets --hosted-zone-id "/hostedzone/Z16P7IEWFWZ4RB" \
+    --query "ResourceRecordSets[?Name == 'nginx.external-dns-test.teapot.zalan.do.']|[?Type == 'CNAME']"
+[
+    {
+        "ResourceRecords": [
+            {
+                "Value": "ae11c2360188411e7951602725593fd1-1224345803.eu-central-1.elb.amazonaws.com"
+            }
+        ],
+        "Type": "CNAME",
+        "Name": "nginx.external-dns-test.teapot.zalan.do.",
+        "TTL": 300
+    }
+]
+```
+
+Let's check that we can resolve this DNS name. We'll ask the nameservers assigned to your zone first.
+
+```console
+$ dig +short @ns-1455.awsdns-53.org. nginx.external-dns-test.teapot.zalan.do.
+ae11c2360188411e7951602725593fd1-1224345803.eu-central-1.elb.amazonaws.com.
+```
+
+If you hooked up your DNS zone with its parent zone correctly you can use `curl` to access your site.
+
+```console
+$ curl nginx.external-dns-test.teapot.zalan.do.
+<!DOCTYPE html>
+<html>
+<head>
+<title>Welcome to nginx!</title>
+...
+</head>
+<body>
+...
+</body>
+</html>
+```
+
+Ingress objects on AWS require a separately deployed Ingress controller which we'll describe in another tutorial.
+
+## Clean up
+
+Make sure to delete all Service objects before terminating the cluster so all load balancers get cleaned up correctly.
+
+```console
+$ kubectl delete service nginx
+```
+
+Give ExternalDNS some time to clean up the DNS records for you. Then delete the hosted zone.
+
+```console
+$ aws route53 delete-hosted-zone --id /hostedzone/Z16P7IEWFWZ4RB
+```

docs/tutorials/gke.md

 # Setting up ExternalDNS on Google Container Engine
 
-This tutorial describes how to setup `external-dns` for usage within a GKE cluster.
+This tutorial describes how to setup ExternalDNS for usage within a GKE cluster.
 
 Setup your environment to work with Google Cloud Platform. Fill in your values as needed, e.g. target project.
 
@@ -48,7 +48,7 @@ $ gcloud dns record-sets transaction add ns-cloud-e{1..4}.googledomains.com. \
 $ gcloud dns record-sets transaction execute --zone "gcp-zalan-do"
 ```
 
-If you decide not to create a new zone but reuse an existing one, make sure it's currently **unused** and **empty**. This version of `external-dns` will remove all records it doesn't recognize from the zone.
+If you decide not to create a new zone but reuse an existing one, make sure it's currently **unused** and **empty**. This version of ExternalDNS will remove all records it doesn't recognize from the zone.
 
 Connect your `kubectl` client to the cluster you just created.
 
@@ -56,7 +56,7 @@ Connect your `kubectl` client to the cluster you just created.
 gcloud container clusters get-credentials "external-dns"
 ```
 
-Apply the following manifest file to deploy `external-dns`.
+Apply the following manifest file to deploy ExternalDNS.
 
 ```yaml
 apiVersion: extensions/v1beta1
@@ -86,7 +86,7 @@ spec:
 
 Use `dry-run=true` if you want to be extra careful on the first run. Note, that you will not see any records created when you are running in dry-run mode. You can, however, inspect the logs and watch what would have been done.
 
-Create the following sample application to test that `external-dns` works.
+Create the following sample application to test that ExternalDNS works.
 
 ```yaml
 apiVersion: v1
@@ -216,7 +216,7 @@ $ kubectl delete service nginx
 $ kubectl delete ingress nginx
 ```
 
-Give `external-dns` some time to clean up the DNS records for you. Then delete the managed zone and cluster.
+Give ExternalDNS some time to clean up the DNS records for you. Then delete the managed zone and cluster.
 
 ```console
 $ gcloud dns managed-zones delete "external-dns-test-gcp-zalan-do"

provider/aws.go

@@ -149,7 +149,12 @@ func (p *AWSProvider) Records(zone string) ([]*endpoint.Endpoint, error) {
 
 	f := func(resp *route53.ListResourceRecordSetsOutput, lastPage bool) (shouldContinue bool) {
 		for _, r := range resp.ResourceRecordSets {
-			if aws.StringValue(r.Type) != route53.RRTypeA {
+			// TODO(linki, ownership): Remove once ownership system is in place.
+			// See: https://github.com/kubernetes-incubator/external-dns/pull/122/files/74e2c3d3e237411e619aefc5aab694742001cdec#r109863370
+			switch aws.StringValue(r.Type) {
+			case route53.RRTypeA, route53.RRTypeCname:
+				break
+			default:
 				continue
 			}
 
@@ -255,7 +260,7 @@ func newChange(action string, endpoint *endpoint.Endpoint) *route53.Change {
 				},
 			},
 			TTL:  aws.Int64(300),
-			Type: aws.String(route53.RRTypeA),
+			Type: aws.String(suitableType(endpoint.Target)),
 		},
 	}
 

provider/aws_test.go

@@ -18,6 +18,7 @@ package provider
 
 import (
 	"fmt"
+	"net"
 	"strings"
 	"testing"
 
@@ -83,6 +84,14 @@ func (r *Route53APIStub) ChangeResourceRecordSets(input *route53.ChangeResourceR
 	}
 
 	for _, change := range input.ChangeBatch.Changes {
+		if aws.StringValue(change.ResourceRecordSet.Type) == route53.RRTypeA {
+			for _, rrs := range change.ResourceRecordSet.ResourceRecords {
+				if net.ParseIP(aws.StringValue(rrs.Value)) == nil {
+					return nil, fmt.Errorf("A records must point to IPs")
+				}
+			}
+		}
+
 		key := aws.StringValue(change.ResourceRecordSet.Name) + "::" + aws.StringValue(change.ResourceRecordSet.Type)
 		switch aws.StringValue(change.Action) {
 		case route53.ChangeActionCreate:
@@ -358,6 +367,20 @@ func TestAWSUpdateRecords(t *testing.T) {
 	if !found {
 		t.Fatal("update-test.ext-dns-test.teapot.zalan.do. should point to 1.2.3.4")
 	}
+
+	found = false
+
+	for _, r := range records {
+		if r.DNSName == "update-test.ext-dns-test.teapot.zalan.do." {
+			if r.Target == "8.8.8.8" {
+				found = true
+			}
+		}
+	}
+
+	if found {
+		t.Fatal("update-test.ext-dns-test.teapot.zalan.do. should point to 1.2.3.4")
+	}
 }
 
 func TestAWSDeleteRecords(t *testing.T) {
@@ -472,6 +495,20 @@ func TestAWSApply(t *testing.T) {
 		t.Fatal("update-test.ext-dns-test.teapot.zalan.do. should point to 1.2.3.4")
 	}
 
+	found = false
+
+	for _, r := range records {
+		if r.DNSName == "update-test.ext-dns-test.teapot.zalan.do." {
+			if r.Target == "8.8.8.8" {
+				found = true
+			}
+		}
+	}
+
+	if found {
+		t.Fatal("update-test.ext-dns-test.teapot.zalan.do. should point to 1.2.3.4")
+	}
+
 	// delete validation
 
 	found = false
@@ -580,6 +617,20 @@ func TestAWSUpdateRecordDryRun(t *testing.T) {
 	if found {
 		t.Fatal("update-test.ext-dns-test.teapot.zalan.do. should not point to 1.2.3.4")
 	}
+
+	found = false
+
+	for _, r := range records {
+		if r.DNSName == "update-test.ext-dns-test.teapot.zalan.do." {
+			if r.Target == "8.8.8.8" {
+				found = true
+			}
+		}
+	}
+
+	if !found {
+		t.Fatal("update-test.ext-dns-test.teapot.zalan.do. should point to 8.8.8.8")
+	}
 }
 
 func TestAWSDeleteRecordDryRun(t *testing.T) {
@@ -698,6 +749,20 @@ func TestAWSApplyDryRun(t *testing.T) {
 		t.Fatal("update-test.ext-dns-test.teapot.zalan.do. should not point to 1.2.3.4")
 	}
 
+	found = false
+
+	for _, r := range records {
+		if r.DNSName == "update-test.ext-dns-test.teapot.zalan.do." {
+			if r.Target == "8.8.8.8" {
+				found = true
+			}
+		}
+	}
+
+	if !found {
+		t.Fatal("update-test.ext-dns-test.teapot.zalan.do. should point to 8.8.8.8")
+	}
+
 	// delete validation
 
 	found = false
@@ -713,6 +778,238 @@ func TestAWSApplyDryRun(t *testing.T) {
 	}
 }
 
+func TestAWSCreateRecordsCNAME(t *testing.T) {
+	provider := newAWSProvider(t, false)
+
+	_, err := provider.CreateZone("ext-dns-test.teapot.zalan.do.")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	records := []*endpoint.Endpoint{{DNSName: "create-test.ext-dns-test.teapot.zalan.do.", Target: "foo.elb.amazonaws.com"}}
+
+	err = provider.CreateRecords("ext-dns-test.teapot.zalan.do.", records)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	records, err = provider.Records("ext-dns-test.teapot.zalan.do.")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	found := false
+
+	for _, r := range records {
+		if r.DNSName == "create-test.ext-dns-test.teapot.zalan.do." {
+			if r.Target == "foo.elb.amazonaws.com" {
+				found = true
+			}
+		}
+	}
+
+	if !found {
+		t.Fatal("create-test.ext-dns-test.teapot.zalan.do. should be there")
+	}
+}
+
+func TestAWSUpdateRecordsCNAME(t *testing.T) {
+	provider := newAWSProvider(t, false)
+
+	_, err := provider.CreateZone("ext-dns-test.teapot.zalan.do.")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	oldRecords := []*endpoint.Endpoint{{DNSName: "update-test.ext-dns-test.teapot.zalan.do.", Target: "foo.elb.amazonaws.com"}}
+
+	err = provider.CreateRecords("ext-dns-test.teapot.zalan.do.", oldRecords)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	newRecords := []*endpoint.Endpoint{{DNSName: "update-test.ext-dns-test.teapot.zalan.do.", Target: "bar.elb.amazonaws.com"}}
+
+	err = provider.UpdateRecords("ext-dns-test.teapot.zalan.do.", newRecords, oldRecords)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	records, err := provider.Records("ext-dns-test.teapot.zalan.do.")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	found := false
+
+	for _, r := range records {
+		if r.DNSName == "update-test.ext-dns-test.teapot.zalan.do." {
+			if r.Target == "bar.elb.amazonaws.com" {
+				found = true
+			}
+		}
+	}
+
+	if !found {
+		t.Fatal("update-test.ext-dns-test.teapot.zalan.do. should point to bar.elb.amazonaws.com")
+	}
+
+	found = false
+
+	for _, r := range records {
+		if r.DNSName == "update-test.ext-dns-test.teapot.zalan.do." {
+			if r.Target == "foo.elb.amazonaws.com" {
+				found = true
+			}
+		}
+	}
+
+	if found {
+		t.Fatal("update-test.ext-dns-test.teapot.zalan.do. should point to bar.elb.amazonaws.com")
+	}
+}
+
+func TestAWSDeleteRecordsCNAME(t *testing.T) {
+	provider := newAWSProvider(t, false)
+
+	_, err := provider.CreateZone("ext-dns-test.teapot.zalan.do.")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	records := []*endpoint.Endpoint{{DNSName: "delete-test.ext-dns-test.teapot.zalan.do.", Target: "baz.elb.amazonaws.com"}}
+
+	err = provider.CreateRecords("ext-dns-test.teapot.zalan.do.", records)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = provider.DeleteRecords("ext-dns-test.teapot.zalan.do.", records)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	records, err = provider.Records("ext-dns-test.teapot.zalan.do.")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	found := false
+
+	for _, r := range records {
+		if r.DNSName == "delete-test.ext-dns-test.teapot.zalan.do." {
+			found = true
+		}
+	}
+
+	if found {
+		t.Fatal("delete-test.ext-dns-test.teapot.zalan.do. should be gone")
+	}
+}
+
+func TestAWSApplyCNAME(t *testing.T) {
+	provider := newAWSProvider(t, false)
+
+	_, err := provider.CreateZone("ext-dns-test.teapot.zalan.do.")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	updateRecords := []*endpoint.Endpoint{{DNSName: "update-test.ext-dns-test.teapot.zalan.do.", Target: "foo.elb.amazonaws.com"}}
+
+	err = provider.CreateRecords("ext-dns-test.teapot.zalan.do.", updateRecords)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	deleteRecords := []*endpoint.Endpoint{{DNSName: "delete-test.ext-dns-test.teapot.zalan.do.", Target: "baz.elb.amazonaws.com"}}
+
+	err = provider.CreateRecords("ext-dns-test.teapot.zalan.do.", deleteRecords)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	createRecords := []*endpoint.Endpoint{{DNSName: "create-test.ext-dns-test.teapot.zalan.do.", Target: "foo.elb.amazonaws.com"}}
+	updateNewRecords := []*endpoint.Endpoint{{DNSName: "update-test.ext-dns-test.teapot.zalan.do.", Target: "bar.elb.amazonaws.com"}}
+
+	changes := &plan.Changes{
+		Create:    createRecords,
+		UpdateNew: updateNewRecords,
+		UpdateOld: updateRecords,
+		Delete:    deleteRecords,
+	}
+
+	err = provider.ApplyChanges("ext-dns-test.teapot.zalan.do.", changes)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// create validation
+
+	records, err := provider.Records("ext-dns-test.teapot.zalan.do.")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	found := false
+
+	for _, r := range records {
+		if r.DNSName == "create-test.ext-dns-test.teapot.zalan.do." {
+			if r.Target == "foo.elb.amazonaws.com" {
+				found = true
+			}
+		}
+	}
+
+	if !found {
+		t.Fatal("create-test.ext-dns-test.teapot.zalan.do. should be there")
+	}
+
+	// update validation
+
+	found = false
+
+	for _, r := range records {
+		if r.DNSName == "update-test.ext-dns-test.teapot.zalan.do." {
+			if r.Target == "bar.elb.amazonaws.com" {
+				found = true
+			}
+		}
+	}
+
+	if !found {
+		t.Fatal("update-test.ext-dns-test.teapot.zalan.do. should point to bar.elb.amazonaws.com")
+	}
+
+	found = false
+
+	for _, r := range records {
+		if r.DNSName == "update-test.ext-dns-test.teapot.zalan.do." {
+			if r.Target == "foo.elb.amazonaws.com" {
+				found = true
+			}
+		}
+	}
+
+	if found {
+		t.Fatal("update-test.ext-dns-test.teapot.zalan.do. should point to bar.elb.amazonaws.com")
+	}
+
+	// delete validation
+
+	found = false
+
+	for _, r := range records {
+		if r.DNSName == "delete-test.ext-dns-test.teapot.zalan.do." {
+			found = true
+		}
+	}
+
+	if found {
+		t.Fatal("delete-test.ext-dns-test.teapot.zalan.do. should be gone")
+	}
+}
+
 func newAWSProvider(t *testing.T, dryRun bool) *AWSProvider {
 	client := NewRoute53APIStub()
 

provider/google.go

@@ -182,7 +182,12 @@ func (p *googleProvider) DeleteZone(name string) error {
 func (p *googleProvider) Records(zone string) (endpoints []*endpoint.Endpoint, _ error) {
 	f := func(resp *dns.ResourceRecordSetsListResponse) error {
 		for _, r := range resp.Rrsets {
-			if r.Type != "A" {
+			// TODO(linki, ownership): Remove once ownership system is in place.
+			// See: https://github.com/kubernetes-incubator/external-dns/pull/122/files/74e2c3d3e237411e619aefc5aab694742001cdec#r109863370
+			switch r.Type {
+			case "A", "CNAME":
+				break
+			default:
 				continue
 			}
 
@@ -289,7 +294,7 @@ func newRecord(endpoint *endpoint.Endpoint) *dns.ResourceRecordSet {
 		Name:    endpoint.DNSName,
 		Rrdatas: []string{endpoint.Target},
 		Ttl:     300,
-		Type:    "A",
+		Type:    suitableType(endpoint.Target),
 	}
 }
 

provider/google_test.go

@@ -34,11 +34,16 @@ var (
 	expectedRecordSets = []*dns.ResourceRecordSet{
 		{
 			Type:    "A",
-			Name:    "expected",
-			Rrdatas: []string{"target"},
+			Name:    "expected-1",
+			Rrdatas: []string{"8.8.8.8"},
 		},
 		{
 			Type:    "CNAME",
+			Name:    "expected-2",
+			Rrdatas: []string{"target.com"},
+		},
+		{
+			Type:    "NS",
 			Name:    "unexpected",
 			Rrdatas: []string{"target"},
 		},

provider/provider.go

@@ -17,6 +17,8 @@ limitations under the License.
 package provider
 
 import (
+	"net"
+
 	"github.com/kubernetes-incubator/external-dns/endpoint"
 	"github.com/kubernetes-incubator/external-dns/plan"
 )
@@ -26,3 +28,13 @@ type Provider interface {
 	Records(zone string) ([]*endpoint.Endpoint, error)
 	ApplyChanges(zone string, changes *plan.Changes) error
 }
+
+// suitableType returns the DNS resource record type suitable for the target.
+// In this case type A for IPs and type CNAME for everything else.
+func suitableType(target string) string {
+	if net.ParseIP(target) == nil {
+		return "CNAME"
+	}
+
+	return "A"
+}

source/ingress.go

@@ -17,8 +17,6 @@ limitations under the License.
 package source
 
 import (
-	"strings"
-
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/pkg/api/v1"
 	"k8s.io/client-go/pkg/apis/extensions/v1beta1"
@@ -76,15 +74,10 @@ func endpointsFromIngress(ing *v1beta1.Ingress) []*endpoint.Endpoint {
 				endpoints = append(endpoints, endpoint.NewEndpoint(sanitizeHostname(rule.Host), lb.IP))
 			}
 			if lb.Hostname != "" {
-				endpoints = append(endpoints, endpoint.NewEndpoint(sanitizeHostname(rule.Host), lb.Hostname))
+				endpoints = append(endpoints, endpoint.NewEndpoint(sanitizeHostname(rule.Host), sanitizeHostname(lb.Hostname)))
 			}
 		}
 	}
 
 	return endpoints
 }
-
-// sanitizeHostname appends a trailing dot to a hostname if it's missing.
-func sanitizeHostname(hostname string) string {
-	return strings.Trim(hostname, ".") + "."
-}

source/ingress_test.go

@@ -42,13 +42,13 @@ func testEndpointsFromIngress(t *testing.T) {
 		{
 			title: "one rule.host one lb.hostname",
 			ingress: fakeIngress{
-				dnsnames:  []string{"foo.bar"},
-				hostnames: []string{"lb.com"},
+				dnsnames:  []string{"foo.bar"}, // Kubernetes requires removal of trailing dot
+				hostnames: []string{"lb.com"},  // Kubernetes omits the trailing dot
 			},
 			expected: []*endpoint.Endpoint{
 				{
 					DNSName: "foo.bar.",
-					Target:  "lb.com",
+					Target:  "lb.com.",
 				},
 			},
 		},
@@ -83,11 +83,11 @@ func testEndpointsFromIngress(t *testing.T) {
 				},
 				{
 					DNSName: "foo.bar.",
-					Target:  "elb.com",
+					Target:  "elb.com.",
 				},
 				{
 					DNSName: "foo.bar.",
-					Target:  "alb.com",
+					Target:  "alb.com.",
 				},
 			},
 		},
@@ -159,7 +159,7 @@ func testIngressEndpoints(t *testing.T) {
 				},
 				{
 					DNSName: "new.org.",
-					Target:  "lb.com",
+					Target:  "lb.com.",
 				},
 			},
 		},
@@ -187,7 +187,7 @@ func testIngressEndpoints(t *testing.T) {
 				},
 				{
 					DNSName: "new.org.",
-					Target:  "lb.com",
+					Target:  "lb.com.",
 				},
 			},
 		},

source/service.go

@@ -76,10 +76,10 @@ func endpointsFromService(svc *v1.Service) []*endpoint.Endpoint {
 	// Create a corresponding endpoint for each configured external entrypoint.
 	for _, lb := range svc.Status.LoadBalancer.Ingress {
 		if lb.IP != "" {
-			endpoints = append(endpoints, endpoint.NewEndpoint(hostname, lb.IP))
+			endpoints = append(endpoints, endpoint.NewEndpoint(sanitizeHostname(hostname), lb.IP))
 		}
 		if lb.Hostname != "" {
-			endpoints = append(endpoints, endpoint.NewEndpoint(hostname, lb.Hostname))
+			endpoints = append(endpoints, endpoint.NewEndpoint(sanitizeHostname(hostname), sanitizeHostname(lb.Hostname)))
 		}
 	}
 

source/service_test.go

@@ -59,11 +59,11 @@ func testServiceEndpoints(t *testing.T) {
 			"testing",
 			"foo",
 			map[string]string{
-				hostnameAnnotationKey: "foo.example.org",
+				hostnameAnnotationKey: "foo.example.org.",
 			},
 			[]string{"1.2.3.4"},
 			[]*endpoint.Endpoint{
-				{DNSName: "foo.example.org", Target: "1.2.3.4"},
+				{DNSName: "foo.example.org.", Target: "1.2.3.4"},
 			},
 		},
 		{
@@ -72,11 +72,25 @@ func testServiceEndpoints(t *testing.T) {
 			"testing",
 			"foo",
 			map[string]string{
-				hostnameAnnotationKey: "foo.example.org",
+				hostnameAnnotationKey: "foo.example.org.",
 			},
-			[]string{"lb.example.com"},
+			[]string{"lb.example.com"}, // Kubernetes omits the trailing dot
 			[]*endpoint.Endpoint{
-				{DNSName: "foo.example.org", Target: "lb.example.com"},
+				{DNSName: "foo.example.org.", Target: "lb.example.com."},
+			},
+		},
+		{
+			"annotated services can omit trailing dot",
+			"",
+			"testing",
+			"foo",
+			map[string]string{
+				hostnameAnnotationKey: "foo.example.org", // Trailing dot is omitted
+			},
+			[]string{"1.2.3.4", "lb.example.com"}, // Kubernetes omits the trailing dot
+			[]*endpoint.Endpoint{
+				{DNSName: "foo.example.org.", Target: "1.2.3.4"},
+				{DNSName: "foo.example.org.", Target: "lb.example.com."},
 			},
 		},
 		{
@@ -86,11 +100,11 @@ func testServiceEndpoints(t *testing.T) {
 			"foo",
 			map[string]string{
 				controllerAnnotationKey: controllerAnnotationValue,
-				hostnameAnnotationKey:   "foo.example.org",
+				hostnameAnnotationKey:   "foo.example.org.",
 			},
 			[]string{"1.2.3.4"},
 			[]*endpoint.Endpoint{
-				{DNSName: "foo.example.org", Target: "1.2.3.4"},
+				{DNSName: "foo.example.org.", Target: "1.2.3.4"},
 			},
 		},
 		{
@@ -100,7 +114,7 @@ func testServiceEndpoints(t *testing.T) {
 			"foo",
 			map[string]string{
 				controllerAnnotationKey: "some-other-tool",
-				hostnameAnnotationKey:   "foo.example.org",
+				hostnameAnnotationKey:   "foo.example.org.",
 			},
 			[]string{"1.2.3.4"},
 			[]*endpoint.Endpoint{},
@@ -111,11 +125,11 @@ func testServiceEndpoints(t *testing.T) {
 			"testing",
 			"foo",
 			map[string]string{
-				hostnameAnnotationKey: "foo.example.org",
+				hostnameAnnotationKey: "foo.example.org.",
 			},
 			[]string{"1.2.3.4"},
 			[]*endpoint.Endpoint{
-				{DNSName: "foo.example.org", Target: "1.2.3.4"},
+				{DNSName: "foo.example.org.", Target: "1.2.3.4"},
 			},
 		},
 		{
@@ -124,7 +138,7 @@ func testServiceEndpoints(t *testing.T) {
 			"other-testing",
 			"foo",
 			map[string]string{
-				hostnameAnnotationKey: "foo.example.org",
+				hostnameAnnotationKey: "foo.example.org.",
 			},
 			[]string{"1.2.3.4"},
 			[]*endpoint.Endpoint{},
@@ -135,11 +149,11 @@ func testServiceEndpoints(t *testing.T) {
 			"other-testing",
 			"foo",
 			map[string]string{
-				hostnameAnnotationKey: "foo.example.org",
+				hostnameAnnotationKey: "foo.example.org.",
 			},
 			[]string{"1.2.3.4"},
 			[]*endpoint.Endpoint{
-				{DNSName: "foo.example.org", Target: "1.2.3.4"},
+				{DNSName: "foo.example.org.", Target: "1.2.3.4"},
 			},
 		},
 		{
@@ -148,7 +162,7 @@ func testServiceEndpoints(t *testing.T) {
 			"testing",
 			"foo",
 			map[string]string{
-				hostnameAnnotationKey: "foo.example.org",
+				hostnameAnnotationKey: "foo.example.org.",
 			},
 			[]string{},
 			[]*endpoint.Endpoint{},
@@ -159,12 +173,12 @@ func testServiceEndpoints(t *testing.T) {
 			"testing",
 			"foo",
 			map[string]string{
-				hostnameAnnotationKey: "foo.example.org",
+				hostnameAnnotationKey: "foo.example.org.",
 			},
 			[]string{"1.2.3.4", "8.8.8.8"},
 			[]*endpoint.Endpoint{
-				{DNSName: "foo.example.org", Target: "1.2.3.4"},
-				{DNSName: "foo.example.org", Target: "8.8.8.8"},
+				{DNSName: "foo.example.org.", Target: "1.2.3.4"},
+				{DNSName: "foo.example.org.", Target: "8.8.8.8"},
 			},
 		},
 	} {
@@ -222,7 +236,7 @@ func BenchmarkServiceEndpoints(b *testing.B) {
 			Namespace: "testing",
 			Name:      "foo",
 			Annotations: map[string]string{
-				hostnameAnnotationKey: "foo.example.org",
+				hostnameAnnotationKey: "foo.example.org.",
 			},
 		},
 		Status: v1.ServiceStatus{

source/source.go

@@ -17,6 +17,8 @@ limitations under the License.
 package source
 
 import (
+	"strings"
+
 	"github.com/kubernetes-incubator/external-dns/endpoint"
 )
 
@@ -33,3 +35,8 @@ const (
 type Source interface {
 	Endpoints() ([]*endpoint.Endpoint, error)
 }
+
+// sanitizeHostname appends a trailing dot to a hostname if it's missing.
+func sanitizeHostname(hostname string) string {
+	return strings.Trim(hostname, ".") + "."
+}