Allow apiserver to choose preferred kubelet address type

pkg/util/node/BUILD

@@ -22,3 +22,14 @@ go_library(
         "//vendor:github.com/golang/glog",
     ],
 )
+
+go_test(
+    name = "go_default_test",
+    srcs = ["node_test.go"],
+    library = "go_default_library",
+    tags = ["automanaged"],
+    deps = [
+        "//pkg/api:go_default_library",
+        "//pkg/api/unversioned:go_default_library",
+    ],
+)

pkg/util/node/node.go

@@ -43,6 +43,26 @@ func GetHostname(hostnameOverride string) string {
 	return strings.ToLower(strings.TrimSpace(hostname))
 }
 
+// GetPreferredNodeAddress returns the address of the provided node, using the provided preference order.
+// If none of the preferred address types are found, an error is returned.
+func GetPreferredNodeAddress(node *api.Node, preferredAddressTypes []api.NodeAddressType) (string, error) {
+	for _, addressType := range preferredAddressTypes {
+		for _, address := range node.Status.Addresses {
+			if address.Type == addressType {
+				return address.Address, nil
+			}
+		}
+		// If hostname was requested and no Hostname address was registered...
+		if addressType == api.NodeHostName {
+			// ...fall back to the kubernetes.io/hostname label for compatibility with kubelets before 1.5
+			if hostname, ok := node.Labels[unversioned.LabelHostname]; ok && len(hostname) > 0 {
+				return hostname, nil
+			}
+		}
+	}
+	return "", fmt.Errorf("no preferred addresses found; known addresses: %v", node.Status.Addresses)
+}
+
 // GetNodeHostIP returns the provided node's IP, based on the priority:
 // 1. NodeInternalIP
 // 2. NodeExternalIP

pkg/util/node/node_test.go

@@ -0,0 +1,90 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package node
+
+import (
+	"testing"
+
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/api/unversioned"
+)
+
+func TestGetPreferredAddress(t *testing.T) {
+	testcases := map[string]struct {
+		Labels      map[string]string
+		Addresses   []api.NodeAddress
+		Preferences []api.NodeAddressType
+
+		ExpectErr     string
+		ExpectAddress string
+	}{
+		"no addresses": {
+			ExpectErr: "no preferred addresses found; known addresses: []",
+		},
+		"missing address": {
+			Addresses: []api.NodeAddress{
+				{Type: api.NodeInternalIP, Address: "1.2.3.4"},
+			},
+			Preferences: []api.NodeAddressType{api.NodeHostName},
+			ExpectErr:   "no preferred addresses found; known addresses: [{InternalIP 1.2.3.4}]",
+		},
+		"found address": {
+			Addresses: []api.NodeAddress{
+				{Type: api.NodeInternalIP, Address: "1.2.3.4"},
+				{Type: api.NodeExternalIP, Address: "1.2.3.5"},
+				{Type: api.NodeExternalIP, Address: "1.2.3.7"},
+			},
+			Preferences:   []api.NodeAddressType{api.NodeHostName, api.NodeExternalIP},
+			ExpectAddress: "1.2.3.5",
+		},
+		"found hostname address": {
+			Labels: map[string]string{unversioned.LabelHostname: "label-hostname"},
+			Addresses: []api.NodeAddress{
+				{Type: api.NodeExternalIP, Address: "1.2.3.5"},
+				{Type: api.NodeHostName, Address: "status-hostname"},
+			},
+			Preferences:   []api.NodeAddressType{api.NodeHostName, api.NodeExternalIP},
+			ExpectAddress: "status-hostname",
+		},
+		"found label address": {
+			Labels: map[string]string{unversioned.LabelHostname: "label-hostname"},
+			Addresses: []api.NodeAddress{
+				{Type: api.NodeExternalIP, Address: "1.2.3.5"},
+			},
+			Preferences:   []api.NodeAddressType{api.NodeHostName, api.NodeExternalIP},
+			ExpectAddress: "label-hostname",
+		},
+	}
+
+	for k, tc := range testcases {
+		node := &api.Node{
+			ObjectMeta: api.ObjectMeta{Labels: tc.Labels},
+			Status:     api.NodeStatus{Addresses: tc.Addresses},
+		}
+		address, err := GetPreferredNodeAddress(node, tc.Preferences)
+		errString := ""
+		if err != nil {
+			errString = err.Error()
+		}
+		if errString != tc.ExpectErr {
+			t.Errorf("%s: expected err=%q, got %q", k, tc.ExpectErr, errString)
+		}
+		if address != tc.ExpectAddress {
+			t.Errorf("%s: expected address=%q, got %q", k, tc.ExpectAddress, address)
+		}
+	}
+}