chore(source/node): template expansion (#5498)

docs/advanced/fqdn-templating.md

@@ -316,7 +316,7 @@ By setting the hostname annotation in the ingress resource, ExternalDNS construc
 
 ```yml
 args:
-  - --fqdn-template="{{range .Status.Addresses}}{{if and (eq .Type \"ExternalIP\") (isIPv4 .Address)}}{{.Address | replace \".\" \"-\"}}{{break}}{{end}}{{end}}.example.com
+  - --fqdn-template="{{range .Status.Addresses}}{{if and (eq .Type \"ExternalIP\") (isIPv4 .Address)}}{{.Address | replace \".\" \"-\"}}{{break}}{{end}}{{end}}.example.com"
 ```
 
 This is a complex template that iternates through a list of a Node's Addresses and creates a FQDN with public IPv4 addresses.

source/node.go

@@ -48,7 +48,7 @@ type nodeSource struct {
 }
 
 // NewNodeSource creates a new nodeSource with the given config.
-func NewNodeSource(ctx context.Context, kubeClient kubernetes.Interface, annotationFilter, fqdnTemplate string, labelSelector labels.Selector, exposeInternalIPv6 bool, excludeUnschedulable bool) (Source, error) {
+func NewNodeSource(ctx context.Context, kubeClient kubernetes.Interface, annotationFilter, fqdnTemplate string, labelSelector labels.Selector, exposeInternalIPv6, excludeUnschedulable bool) (Source, error) {
 	tmpl, err := fqdn.ParseTemplate(fqdnTemplate)
 	if err != nil {
 		return nil, err
@@ -103,8 +103,7 @@ func (ns *nodeSource) Endpoints(ctx context.Context) ([]*endpoint.Endpoint, erro
 	// create endpoints for all nodes
 	for _, node := range nodes {
 		// Check controller annotation to see if we are responsible.
-		controller, ok := node.Annotations[controllerAnnotationKey]
+		if controller, ok := node.Annotations[controllerAnnotationKey]; ok && controller != controllerAnnotationValue {
-		if ok && controller != controllerAnnotationValue {
 			log.Debugf("Skipping node %s because controller value does not match, found: %s, required: %s",
 				node.Name, controller, controllerAnnotationValue)
 			continue
@@ -119,28 +118,8 @@ func (ns *nodeSource) Endpoints(ctx context.Context) ([]*endpoint.Endpoint, erro
 
 		ttl := annotations.TTLFromAnnotations(node.Annotations, fmt.Sprintf("node/%s", node.Name))
 
-		// create new endpoint with the information we already have
-		ep := &endpoint.Endpoint{
-			RecordTTL: ttl,
-		}
-
-		if ns.fqdnTemplate != nil {
-			hostnames, err := fqdn.ExecTemplate(ns.fqdnTemplate, node)
-			if err != nil {
-				return nil, err
-			}
-			hostname := ""
-			if len(hostnames) > 0 {
-				hostname = hostnames[0]
-			}
-			ep.DNSName = hostname
-			log.Debugf("applied template for %s, converting to %s", node.Name, ep.DNSName)
-		} else {
-			ep.DNSName = node.Name
-			log.Debugf("not applying template for %s", node.Name)
-		}
-
 		addrs := annotations.TargetsFromTargetAnnotation(node.Annotations)
+
 		if len(addrs) == 0 {
 			addrs, err = ns.nodeAddresses(node)
 			if err != nil {
@@ -148,12 +127,32 @@ func (ns *nodeSource) Endpoints(ctx context.Context) ([]*endpoint.Endpoint, erro
 			}
 		}
 
-		ep.Labels = endpoint.NewLabels()
+		dnsNames := make(map[string]bool)
+
+		if ns.fqdnTemplate != nil {
+			hostnames, err := fqdn.ExecTemplate(ns.fqdnTemplate, node)
+			if err != nil {
+				return nil, err
+			}
+
+			for _, name := range hostnames {
+				dnsNames[name] = true
+				log.Debugf("applied template for %s, converting to %s", node.Name, name)
+			}
+		} else {
+			dnsNames[node.Name] = true
+			log.Debugf("not applying template for %s", node.Name)
+		}
+
+		for dns := range dnsNames {
+			log.Debugf("adding endpoint with %d targets", len(addrs))
+
 			for _, addr := range addrs {
+				ep := endpoint.NewEndpointWithTTL(dns, suitableType(addr), ttl)
 				log.Debugf("adding endpoint %s target %s", ep, addr)
 				key := endpoint.EndpointKey{
 					DNSName:    ep.DNSName,
-				RecordType: suitableType(addr),
+					RecordType: ep.RecordType,
 				}
 				if _, ok := endpoints[key]; !ok {
 					epCopy := *ep
@@ -163,6 +162,7 @@ func (ns *nodeSource) Endpoints(ctx context.Context) ([]*endpoint.Endpoint, erro
 				endpoints[key].Targets = append(endpoints[key].Targets, addr)
 			}
 		}
+	}
 
 	endpointsSlice := []*endpoint.Endpoint{}
 	for _, ep := range endpoints {
@@ -172,10 +172,10 @@ func (ns *nodeSource) Endpoints(ctx context.Context) ([]*endpoint.Endpoint, erro
 	return endpointsSlice, nil
 }
 
-func (ns *nodeSource) AddEventHandler(ctx context.Context, handler func()) {
+func (ns *nodeSource) AddEventHandler(_ context.Context, _ func()) {
 }
 
-// nodeAddress returns node's externalIP and if that's not found, node's internalIP
+// nodeAddress returns the node's externalIP and if that's not found, the node's internalIP
 // basically what k8s.io/kubernetes/pkg/util/node.GetPreferredNodeAddress does
 func (ns *nodeSource) nodeAddresses(node *v1.Node) ([]string, error) {
 	addresses := map[v1.NodeAddressType][]string{
@@ -223,7 +223,7 @@ func (ns *nodeSource) filterByAnnotations(nodes []*v1.Node) ([]*v1.Node, error)
 	var filteredList []*v1.Node
 
 	for _, node := range nodes {
-		// include node if its annotations match the selector
+		// include a node if its annotations match the selector
 		if selector.Matches(labels.Set(node.Annotations)) {
 			filteredList = append(filteredList, node)
 		}

source/node_fqdn_test.go

@@ -0,0 +1,322 @@
+/*
+Copyright 2025 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 source
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	v1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/labels"
+	"k8s.io/client-go/kubernetes/fake"
+	"sigs.k8s.io/external-dns/endpoint"
+)
+
+func TestNodeSourceNewNodeSourceWithFqdn(t *testing.T) {
+	for _, tt := range []struct {
+		title            string
+		annotationFilter string
+		fqdnTemplate     string
+		expectError      bool
+	}{
+		{
+			title:        "invalid template",
+			expectError:  true,
+			fqdnTemplate: "{{.Name",
+		},
+		{
+			title:       "valid empty template",
+			expectError: false,
+		},
+		{
+			title:        "valid template",
+			expectError:  false,
+			fqdnTemplate: "{{.Name}}-{{.Namespace}}.ext-dns.test.com",
+		},
+		{
+			title:        "complex template",
+			expectError:  false,
+			fqdnTemplate: "{{range .Status.Addresses}}{{if and (eq .Type \"ExternalIP\") (isIPv4 .Address)}}{{.Address | replace \".\" \"-\"}}{{break}}{{end}}{{end}}.ext-dns.test.com",
+		},
+	} {
+		t.Run(tt.title, func(t *testing.T) {
+			_, err := NewNodeSource(
+				t.Context(),
+				fake.NewClientset(),
+				tt.annotationFilter,
+				tt.fqdnTemplate,
+				labels.Everything(),
+				true,
+				true,
+			)
+			if tt.expectError {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+			}
+		})
+	}
+}
+
+func TestNodeSourceFqdnTemplatingExamples(t *testing.T) {
+	for _, tt := range []struct {
+		title        string
+		nodes        []*v1.Node
+		fqdnTemplate string
+		expected     []*endpoint.Endpoint
+	}{
+		{
+			title: "templating expansion with multiple domains",
+			nodes: []*v1.Node{
+				{
+					ObjectMeta: metav1.ObjectMeta{
+						Name: "ip-10-1-176-5.internal",
+					},
+					Status: v1.NodeStatus{
+						Addresses: []v1.NodeAddress{
+							{Type: v1.NodeInternalIP, Address: "10.1.176.1"},
+							{Type: v1.NodeInternalIP, Address: "fc00:f853:ccd:e793::1"},
+						},
+					},
+				},
+			},
+			fqdnTemplate: "{{.Name}}.domainA.com,{{.Name}}.domainB.com",
+			expected: []*endpoint.Endpoint{
+				{DNSName: "ip-10-1-176-5.internal.domainA.com", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"10.1.176.1"}},
+				{DNSName: "ip-10-1-176-5.internal.domainA.com", RecordType: endpoint.RecordTypeAAAA, Targets: endpoint.Targets{"fc00:f853:ccd:e793::1"}},
+				{DNSName: "ip-10-1-176-5.internal.domainB.com", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"10.1.176.1"}},
+				{DNSName: "ip-10-1-176-5.internal.domainB.com", RecordType: endpoint.RecordTypeAAAA, Targets: endpoint.Targets{"fc00:f853:ccd:e793::1"}},
+			},
+		},
+		{
+			title: "templating contains namespace when node namespace is not a valid variable",
+			nodes: []*v1.Node{
+				{
+					ObjectMeta: metav1.ObjectMeta{
+						Name: "node-name",
+					},
+					Status: v1.NodeStatus{
+						Addresses: []v1.NodeAddress{
+							{Type: v1.NodeInternalIP, Address: "10.1.176.1"},
+						},
+					},
+				},
+			},
+			fqdnTemplate: "{{.Name}}.domainA.com,{{ .Name }}.{{ .Namespace }}.example.tld",
+			expected: []*endpoint.Endpoint{
+				{DNSName: "node-name.domainA.com", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"10.1.176.1"}},
+				{DNSName: "node-name..example.tld", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"10.1.176.1"}},
+			},
+		},
+		{
+			title: "templating with external IP and range of addresses",
+			nodes: []*v1.Node{
+				{
+					ObjectMeta: metav1.ObjectMeta{
+						Name: "ip-10-1-176-1",
+					},
+					Status: v1.NodeStatus{
+						Addresses: []v1.NodeAddress{
+							{Type: v1.NodeExternalIP, Address: "243.186.136.160"},
+							{Type: v1.NodeInternalIP, Address: "fc00:f853:ccd:e793::1"},
+						},
+					},
+				},
+			},
+			fqdnTemplate: "{{ range .Status.Addresses }}{{if and (eq .Type \"ExternalIP\") (isIPv4 .Address)}}ip-{{ .Address | replace \".\" \"-\" }}{{ break }}{{ end }}{{ end }}.example.com",
+			expected: []*endpoint.Endpoint{
+				{DNSName: "ip-243-186-136-160.example.com", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"243.186.136.160"}},
+				{DNSName: "ip-243-186-136-160.example.com", RecordType: endpoint.RecordTypeAAAA, Targets: endpoint.Targets{"fc00:f853:ccd:e793::1"}},
+			},
+		},
+		{
+			title: "templating with name definition and ipv4 check",
+			nodes: []*v1.Node{
+				{
+					ObjectMeta: metav1.ObjectMeta{
+						Name: "node-name-ip",
+					},
+					Status: v1.NodeStatus{
+						Addresses: []v1.NodeAddress{
+							{Type: v1.NodeExternalIP, Address: "243.186.136.160"},
+							{Type: v1.NodeInternalIP, Address: "fc00:f853:ccd:e793::1"},
+						},
+					},
+				},
+			},
+			fqdnTemplate: "{{ $name := .Name }}{{ range .Status.Addresses }}{{if (isIPv4 .Address)}}{{ $name }}.ipv4{{ break }}{{ end }}{{ end }}.example.com",
+			expected: []*endpoint.Endpoint{
+				{DNSName: "node-name-ip.ipv4.example.com", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"243.186.136.160"}},
+				{DNSName: "node-name-ip.ipv4.example.com", RecordType: endpoint.RecordTypeAAAA, Targets: endpoint.Targets{"fc00:f853:ccd:e793::1"}},
+			},
+		},
+		{
+			title: "templating with hostname annotation",
+			nodes: []*v1.Node{
+				{
+					ObjectMeta: metav1.ObjectMeta{
+						Name: "ip-10-1-176-1",
+						Annotations: map[string]string{
+							"external-dns.alpha.kubernetes.io/hostname": "ip-10-1-176-1.internal.domain.com",
+						},
+					},
+					Status: v1.NodeStatus{
+						Addresses: []v1.NodeAddress{
+							{Type: v1.NodeExternalIP, Address: "243.186.136.160"},
+							{Type: v1.NodeInternalIP, Address: "fc00:f853:ccd:e793::1"},
+						},
+					},
+				},
+			},
+			fqdnTemplate: "{{.Name}}.example.com",
+			expected: []*endpoint.Endpoint{
+				{DNSName: "ip-10-1-176-1.example.com", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"243.186.136.160"}},
+				{DNSName: "ip-10-1-176-1.example.com", RecordType: endpoint.RecordTypeAAAA, Targets: endpoint.Targets{"fc00:f853:ccd:e793::1"}},
+			},
+		},
+		{
+			title: "templating when target annotation and no external IP",
+			nodes: []*v1.Node{
+				{
+					ObjectMeta: metav1.ObjectMeta{
+						Name:   "node-name",
+						Labels: nil,
+						Annotations: map[string]string{
+							"external-dns.alpha.kubernetes.io/target": "203.2.45.22",
+						},
+					},
+					Status: v1.NodeStatus{
+						Addresses: []v1.NodeAddress{
+							{Type: v1.NodeExternalIP, Address: "243.186.136.160"},
+							{Type: v1.NodeInternalIP, Address: "fc00:f853:ccd:e793::1"},
+						},
+					},
+				},
+			},
+			fqdnTemplate: "{{.Name}}.example.com",
+			expected: []*endpoint.Endpoint{
+				{DNSName: "node-name.example.com", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"203.2.45.22"}},
+			},
+		},
+		{
+			title: "templating with simple annotation expansion",
+			nodes: []*v1.Node{
+				{
+					ObjectMeta: metav1.ObjectMeta{
+						Name: "node-name",
+						Annotations: map[string]string{
+							"workload": "cluster-resources",
+						},
+					},
+					Status: v1.NodeStatus{
+						Addresses: []v1.NodeAddress{
+							{Type: v1.NodeExternalIP, Address: "243.186.136.160"},
+						},
+					},
+				},
+			},
+			fqdnTemplate: "{{ .Name }}.{{ .Annotations.workload }}.domain.tld",
+			expected: []*endpoint.Endpoint{
+				{DNSName: "node-name.cluster-resources.domain.tld", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"243.186.136.160"}},
+			},
+		},
+		{
+			title: "templating with complex labels expansion",
+			nodes: []*v1.Node{
+				{
+					ObjectMeta: metav1.ObjectMeta{
+						Name: "node-name",
+						Labels: map[string]string{
+							"topology.kubernetes.io/region": "eu-west-1",
+						},
+						Annotations: nil,
+					},
+					Spec: v1.NodeSpec{
+						Unschedulable: false,
+					},
+					Status: v1.NodeStatus{
+						Addresses: []v1.NodeAddress{
+							{Type: v1.NodeExternalIP, Address: "243.186.136.160"},
+						},
+					},
+				},
+			},
+			fqdnTemplate: "{{ .Name }}.{{ index .ObjectMeta.Labels \"topology.kubernetes.io/region\" }}.domain.tld",
+			expected: []*endpoint.Endpoint{
+				{DNSName: "node-name.eu-west-1.domain.tld", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"243.186.136.160"}},
+			},
+		},
+		{
+			title: "templating with shared all domain",
+			nodes: []*v1.Node{
+				{
+					ObjectMeta: metav1.ObjectMeta{
+						Name: "node-name-1",
+					},
+					Status: v1.NodeStatus{
+						Addresses: []v1.NodeAddress{
+							{Type: v1.NodeExternalIP, Address: "243.186.136.160"},
+						},
+					},
+				},
+				{
+					ObjectMeta: metav1.ObjectMeta{
+						Name: "node-name-2",
+					},
+					Status: v1.NodeStatus{
+						Addresses: []v1.NodeAddress{
+							{Type: v1.NodeExternalIP, Address: "243.186.136.178"},
+						},
+					},
+				},
+			},
+			fqdnTemplate: "{{ .Name }}.domain.tld,all.example.com",
+			expected: []*endpoint.Endpoint{
+				{DNSName: "all.example.com", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"243.186.136.160", "243.186.136.178"}},
+				{DNSName: "node-name-1.domain.tld", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"243.186.136.160"}},
+				{DNSName: "node-name-2.domain.tld", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"243.186.136.178"}},
+			},
+		},
+	} {
+		t.Run(tt.title, func(t *testing.T) {
+			kubeClient := fake.NewClientset()
+
+			for _, node := range tt.nodes {
+				_, err := kubeClient.CoreV1().Nodes().Create(t.Context(), node, metav1.CreateOptions{})
+				require.NoError(t, err)
+			}
+
+			src, err := NewNodeSource(
+				t.Context(),
+				kubeClient,
+				"",
+				tt.fqdnTemplate,
+				labels.Everything(),
+				true,
+				true,
+			)
+			require.NoError(t, err)
+
+			endpoints, err := src.Endpoints(t.Context())
+			require.NoError(t, err)
+
+			validateEndpoints(t, endpoints, tt.expected)
+		})
+	}
+}

source/node_test.go

@@ -18,10 +18,15 @@ package source
 
 import (
 	"context"
+	"fmt"
+	"maps"
+	"math/rand"
 	"testing"
+	"time"
 
 	log "github.com/sirupsen/logrus"
 	"github.com/sirupsen/logrus/hooks/test"
+	"k8s.io/client-go/kubernetes"
 
 	"sigs.k8s.io/external-dns/internal/testutils"
 
@@ -84,7 +89,7 @@ func testNodeSourceNewNodeSource(t *testing.T) {
 
 			_, err := NewNodeSource(
 				context.TODO(),
-				fake.NewSimpleClientset(),
+				fake.NewClientset(),
 				ti.annotationFilter,
 				ti.fqdnTemplate,
 				labels.Everything(),
@@ -407,7 +412,7 @@ func testNodeSourceEndpoints(t *testing.T) {
 			}
 
 			// Create a Kubernetes testing client
-			kubernetes := fake.NewSimpleClientset()
+			kubeClient := fake.NewClientset()
 
 			node := &v1.Node{
 				ObjectMeta: metav1.ObjectMeta{
@@ -423,13 +428,13 @@ func testNodeSourceEndpoints(t *testing.T) {
 				},
 			}
 
-			_, err := kubernetes.CoreV1().Nodes().Create(context.Background(), node, metav1.CreateOptions{})
+			_, err := kubeClient.CoreV1().Nodes().Create(context.Background(), node, metav1.CreateOptions{})
 			require.NoError(t, err)
 
 			// Create our object under test and get the endpoints.
 			client, err := NewNodeSource(
 				context.TODO(),
-				kubernetes,
+				kubeClient,
 				tc.annotationFilter,
 				tc.fqdnTemplate,
 				labelSelector,
@@ -519,7 +524,7 @@ func testNodeEndpointsWithIPv6(t *testing.T) {
 		}
 
 		// Create a Kubernetes testing client
-		kubernetes := fake.NewSimpleClientset()
+		kubeClient := fake.NewClientset()
 
 		node := &v1.Node{
 			ObjectMeta: metav1.ObjectMeta{
@@ -535,7 +540,7 @@ func testNodeEndpointsWithIPv6(t *testing.T) {
 			},
 		}
 
-		_, err := kubernetes.CoreV1().Nodes().Create(context.Background(), node, metav1.CreateOptions{})
+		_, err := kubeClient.CoreV1().Nodes().Create(t.Context(), node, metav1.CreateOptions{})
 		require.NoError(t, err)
 
 		var hook *test.Hook
@@ -545,8 +550,8 @@ func testNodeEndpointsWithIPv6(t *testing.T) {
 
 		// Create our object under test and get the endpoints.
 		client, err := NewNodeSource(
-			context.TODO(),
+			t.Context(),
-			kubernetes,
+			kubeClient,
 			tc.annotationFilter,
 			tc.fqdnTemplate,
 			labelSelector,
@@ -555,7 +560,7 @@ func testNodeEndpointsWithIPv6(t *testing.T) {
 		)
 		require.NoError(t, err)
 
-		endpoints, err := client.Endpoints(context.Background())
+		endpoints, err := client.Endpoints(t.Context())
 		if tc.expectError {
 			require.Error(t, err)
 		} else {
@@ -570,3 +575,101 @@ func testNodeEndpointsWithIPv6(t *testing.T) {
 		validateEndpoints(t, endpoints, tc.expected)
 	}
 }
+
+func TestResourceLabelIsSetForEachNodeEndpoint(t *testing.T) {
+	kubeClient := fake.NewClientset()
+
+	nodes := helperNodeBuilder().
+		withNode(nil).
+		withNode(nil).
+		withNode(nil).
+		withNode(nil).
+		build()
+
+	for _, node := range nodes.Items {
+		_, err := kubeClient.CoreV1().Nodes().Create(t.Context(), &node, metav1.CreateOptions{})
+		require.NoError(t, err, "Failed to create node %s", node.Name)
+	}
+
+	client, err := NewNodeSource(
+		t.Context(),
+		kubeClient,
+		"",
+		"",
+		labels.Everything(),
+		false,
+		true,
+	)
+	require.NoError(t, err)
+
+	got, err := client.Endpoints(t.Context())
+	require.NoError(t, err)
+	for _, ep := range got {
+		// TODO: node source should always set the resource label key. currently not supported by the node source.
+		assert.Empty(t, ep.Labels, "Labels should not be empty for endpoint %s", ep.DNSName)
+		assert.NotContains(t, ep.Labels, endpoint.ResourceLabelKey)
+	}
+}
+
+type nodeListBuilder struct {
+	nodes []v1.Node
+}
+
+func helperNodeBuilder() *nodeListBuilder {
+	return &nodeListBuilder{nodes: []v1.Node{}}
+}
+
+func (b *nodeListBuilder) withNode(labels map[string]string) *nodeListBuilder {
+	idx := len(b.nodes) + 1
+	nodeName := fmt.Sprintf("ip-10-1-176-%d.internal", idx)
+	b.nodes = append(b.nodes, v1.Node{
+		ObjectMeta: metav1.ObjectMeta{
+			Name: nodeName,
+			Labels: func() map[string]string {
+				base := map[string]string{
+					"test-label":                    "test-value",
+					"name":                          nodeName,
+					"topology.kubernetes.io/region": "eu-west-1",
+					"node.kubernetes.io/lifecycle":  "spot",
+				}
+				maps.Copy(base, labels)
+				return base
+			}(),
+			Annotations: map[string]string{
+				"volumes.kubernetes.io/controller-managed-attach-detach": "true",
+				"alpha.kubernetes.io/provided-node-ip":                   fmt.Sprintf("10.1.176.%d", idx),
+				"external-dns.alpha.kubernetes.io/hostname":              fmt.Sprintf("node-%d.example.com", idx),
+			},
+		},
+		Spec: v1.NodeSpec{
+			Unschedulable: false,
+		},
+		Status: v1.NodeStatus{
+			Addresses: []v1.NodeAddress{
+				{Type: v1.NodeInternalIP, Address: fmt.Sprintf("10.1.176.%d", idx)},
+				{Type: v1.NodeInternalIP, Address: fmt.Sprintf("fc00:f853:ccd:e793::%d", idx)},
+			},
+		},
+	})
+
+	return b
+}
+
+func (b *nodeListBuilder) build() v1.NodeList {
+	if len(b.nodes) > 1 {
+		// Shuffle the result to ensure randomness in the order.
+		rand.New(rand.NewSource(time.Now().UnixNano()))
+		rand.Shuffle(len(b.nodes), func(i, j int) {
+			b.nodes[i], b.nodes[j] = b.nodes[j], b.nodes[i]
+		})
+	}
+	return v1.NodeList{Items: b.nodes}
+}
+
+func (b *nodeListBuilder) apply(t *testing.T, kubeClient kubernetes.Interface) v1.NodeList {
+	for _, node := range b.nodes {
+		_, err := kubeClient.CoreV1().Nodes().Create(t.Context(), &node, metav1.CreateOptions{})
+		require.NoError(t, err, "Failed to create node %s", node.Name)
+	}
+	return v1.NodeList{Items: b.nodes}
+}