Merge pull request #34259 from liggitt/node-dns

Automatic merge from submit-queue (batch tested with PRs 41756, 36344, 34259, 40843, 41526)

add InternalDNS/ExternalDNS node address types

This PR adds internal/external DNS names to the types of NodeAddresses that can be reported by the kubelet.

will spawn follow up issues for cloud provider owners to include these when possible

```release-note
Nodes can now report two additional address types in their status: InternalDNS and ExternalDNS. The apiserver can use `--kubelet-preferred-address-types` to give priority to the type of address it uses to reach nodes.
```

cmd/kube-apiserver/app/options/options.go

@@ -86,9 +86,17 @@ func NewServerRunOptions() *ServerRunOptions {
 			Port:         ports.KubeletPort,
 			ReadOnlyPort: ports.KubeletReadOnlyPort,
 			PreferredAddressTypes: []string{
+				// --override-hostname
 				string(api.NodeHostName),
+
+				// internal, preferring DNS if reported
+				string(api.NodeInternalDNS),
 				string(api.NodeInternalIP),
+
+				// external, preferring DNS if reported
+				string(api.NodeExternalDNS),
 				string(api.NodeExternalIP),
+
 				string(api.NodeLegacyHostIP),
 			},
 			EnableHttps: true,

pkg/api/types.go

@@ -2732,6 +2732,8 @@ const (
 	NodeHostName     NodeAddressType = "Hostname"
 	NodeExternalIP   NodeAddressType = "ExternalIP"
 	NodeInternalIP   NodeAddressType = "InternalIP"
+	NodeExternalDNS  NodeAddressType = "ExternalDNS"
+	NodeInternalDNS  NodeAddressType = "InternalDNS"
 )
 
 type NodeAddress struct {

pkg/api/v1/types.go

@@ -3153,6 +3153,8 @@ const (
 	NodeHostName     NodeAddressType = "Hostname"
 	NodeExternalIP   NodeAddressType = "ExternalIP"
 	NodeInternalIP   NodeAddressType = "InternalIP"
+	NodeExternalDNS  NodeAddressType = "ExternalDNS"
+	NodeInternalDNS  NodeAddressType = "InternalDNS"
 )
 
 // NodeAddress contains information for the node's address.

pkg/cloudprovider/providers/aws/aws.go

@@ -909,6 +909,24 @@ func (c *Cloud) NodeAddresses(name types.NodeName) ([]v1.NodeAddress, error) {
 			addresses = append(addresses, v1.NodeAddress{Type: v1.NodeExternalIP, Address: externalIP})
 		}
 
+		internalDNS, err := c.metadata.GetMetadata("local-hostname")
+		if err != nil || len(internalDNS) == 0 {
+			//TODO: It would be nice to be able to determine the reason for the failure,
+			// but the AWS client masks all failures with the same error description.
+			glog.V(2).Info("Could not determine private DNS from AWS metadata.")
+		} else {
+			addresses = append(addresses, v1.NodeAddress{Type: v1.NodeInternalDNS, Address: internalDNS})
+		}
+
+		externalDNS, err := c.metadata.GetMetadata("public-hostname")
+		if err != nil || len(externalDNS) == 0 {
+			//TODO: It would be nice to be able to determine the reason for the failure,
+			// but the AWS client masks all failures with the same error description.
+			glog.V(2).Info("Could not determine public DNS from AWS metadata.")
+		} else {
+			addresses = append(addresses, v1.NodeAddress{Type: v1.NodeExternalDNS, Address: externalDNS})
+		}
+
 		return addresses, nil
 	}
 	instance, err := c.getInstanceByNodeName(name)
@@ -940,6 +958,14 @@ func (c *Cloud) NodeAddresses(name types.NodeName) ([]v1.NodeAddress, error) {
 		addresses = append(addresses, v1.NodeAddress{Type: v1.NodeExternalIP, Address: ip.String()})
 	}
 
+	if !isNilOrEmpty(instance.PrivateDnsName) {
+		addresses = append(addresses, v1.NodeAddress{Type: v1.NodeInternalDNS, Address: *instance.PrivateDnsName})
+	}
+
+	if !isNilOrEmpty(instance.PublicDnsName) {
+		addresses = append(addresses, v1.NodeAddress{Type: v1.NodeExternalDNS, Address: *instance.PublicDnsName})
+	}
+
 	return addresses, nil
 }
 

pkg/cloudprovider/providers/aws/aws_test.go

@@ -345,6 +345,8 @@ func (self *FakeMetadata) GetMetadata(key string) (string, error) {
 		return aws.StringValue(i.InstanceId), nil
 	} else if key == "local-hostname" {
 		return aws.StringValue(i.PrivateDnsName), nil
+	} else if key == "public-hostname" {
+		return aws.StringValue(i.PublicDnsName), nil
 	} else if key == "local-ipv4" {
 		return aws.StringValue(i.PrivateIpAddress), nil
 	} else if key == "public-ipv4" {
@@ -553,6 +555,7 @@ func TestNodeAddresses(t *testing.T) {
 	instance0.InstanceId = aws.String("i-0")
 	instance0.PrivateDnsName = aws.String("instance-same.ec2.internal")
 	instance0.PrivateIpAddress = aws.String("192.168.0.1")
+	instance0.PublicDnsName = aws.String("instance-same.ec2.external")
 	instance0.PublicIpAddress = aws.String("1.2.3.4")
 	instance0.InstanceType = aws.String("c3.large")
 	instance0.Placement = &ec2.Placement{AvailabilityZone: aws.String("us-east-1a")}
@@ -603,12 +606,14 @@ func TestNodeAddresses(t *testing.T) {
 	if err3 != nil {
 		t.Errorf("Should not error when instance found")
 	}
-	if len(addrs3) != 3 {
+	if len(addrs3) != 5 {
-		t.Errorf("Should return exactly 3 NodeAddresses")
+		t.Errorf("Should return exactly 5 NodeAddresses")
 	}
 	testHasNodeAddress(t, addrs3, v1.NodeInternalIP, "192.168.0.1")
 	testHasNodeAddress(t, addrs3, v1.NodeLegacyHostIP, "192.168.0.1")
 	testHasNodeAddress(t, addrs3, v1.NodeExternalIP, "1.2.3.4")
+	testHasNodeAddress(t, addrs3, v1.NodeExternalDNS, "instance-same.ec2.external")
+	testHasNodeAddress(t, addrs3, v1.NodeInternalDNS, "instance-same.ec2.internal")
 
 	// Fetch from metadata
 	aws4, fakeServices := mockInstancesResp(&instance0, []*ec2.Instance{&instance0})