feat(source): support --event flags with sources pod and node (#5642)

Signed-off-by: ivan katliarchuk <ivan.katliarchuk@gmail.com>

Author: ivankatliarchuk

source/node.go

@@ -27,7 +27,6 @@ import (
 	kubeinformers "k8s.io/client-go/informers"
 	coreinformers "k8s.io/client-go/informers/core/v1"
 	"k8s.io/client-go/kubernetes"
-	"k8s.io/client-go/tools/cache"
 
 	"sigs.k8s.io/external-dns/endpoint"
 	"sigs.k8s.io/external-dns/source/annotations"
@@ -69,13 +68,7 @@ func NewNodeSource(
 	nodeInformer := informerFactory.Core().V1().Nodes()
 
 	// Add default resource event handler to properly initialize informer.
-	nodeInformer.Informer().AddEventHandler(
-		cache.ResourceEventHandlerFuncs{
-			AddFunc: func(obj interface{}) {
-				log.Debug("node added")
-			},
-		},
-	)
+	_, _ = nodeInformer.Informer().AddEventHandler(informers.DefaultEventHandler())
 
 	informerFactory.Start(ctx.Done())
 
@@ -172,7 +165,8 @@ func (ns *nodeSource) Endpoints(_ context.Context) ([]*endpoint.Endpoint, error)
 	return endpointsSlice, nil
 }
 
-func (ns *nodeSource) AddEventHandler(_ context.Context, _ func()) {
+func (ns *nodeSource) AddEventHandler(_ context.Context, handler func()) {
+	_, _ = ns.nodeInformer.Informer().AddEventHandler(eventHandlerFunc(handler))
 }
 
 // nodeAddress returns the node's externalIP and if that's not found, the node's internalIP

source/node_test.go

@@ -26,7 +26,10 @@ import (
 
 	log "github.com/sirupsen/logrus"
 	"github.com/sirupsen/logrus/hooks/test"
+	"github.com/stretchr/testify/mock"
 	"k8s.io/client-go/kubernetes"
+	corev1lister "k8s.io/client-go/listers/core/v1"
+	"k8s.io/client-go/tools/cache"
 
 	"sigs.k8s.io/external-dns/internal/testutils"
 
@@ -619,6 +622,39 @@ func TestResourceLabelIsSetForEachNodeEndpoint(t *testing.T) {
 	}
 }
 
+func TestNodeSource_AddEventHandler(t *testing.T) {
+	fakeInformer := new(fakeNodeInformer)
+	inf := testInformer{}
+	fakeInformer.On("Informer").Return(&inf)
+
+	nSource := &nodeSource{
+		nodeInformer: fakeInformer,
+	}
+
+	handlerCalled := false
+	handler := func() { handlerCalled = true }
+
+	nSource.AddEventHandler(t.Context(), handler)
+
+	fakeInformer.AssertNumberOfCalls(t, "Informer", 1)
+	assert.False(t, handlerCalled)
+	assert.Equal(t, 1, inf.times)
+}
+
+type fakeNodeInformer struct {
+	mock.Mock
+	informer cache.SharedIndexInformer
+}
+
+func (f *fakeNodeInformer) Informer() cache.SharedIndexInformer {
+	args := f.Called()
+	return args.Get(0).(cache.SharedIndexInformer)
+}
+
+func (f *fakeNodeInformer) Lister() corev1lister.NodeLister {
+	return corev1lister.NewNodeLister(f.Informer().GetIndexer())
+}
+
 type nodeListBuilder struct {
 	nodes []v1.Node
 }

source/pod.go

@@ -29,7 +29,6 @@ import (
 	kubeinformers "k8s.io/client-go/informers"
 	coreinformers "k8s.io/client-go/informers/core/v1"
 	"k8s.io/client-go/kubernetes"
-	"k8s.io/client-go/tools/cache"
 
 	"sigs.k8s.io/external-dns/endpoint"
 	"sigs.k8s.io/external-dns/source/annotations"
@@ -76,18 +75,8 @@ func NewPodSource(
 		return nil, fmt.Errorf("failed to add indexers to pod informer: %w", err)
 	}
 
-	_, _ = podInformer.Informer().AddEventHandler(
-		cache.ResourceEventHandlerFuncs{
-			AddFunc: func(obj interface{}) {
-			},
-		},
-	)
-	_, _ = nodeInformer.Informer().AddEventHandler(
-		cache.ResourceEventHandlerFuncs{
-			AddFunc: func(obj interface{}) {
-			},
-		},
-	)
+	_, _ = podInformer.Informer().AddEventHandler(informers.DefaultEventHandler())
+	_, _ = nodeInformer.Informer().AddEventHandler(informers.DefaultEventHandler())
 
 	informerFactory.Start(ctx.Done())
 
@@ -114,7 +103,8 @@ func NewPodSource(
 	}, nil
 }
 
-func (*podSource) AddEventHandler(_ context.Context, _ func()) {
+func (ps *podSource) AddEventHandler(_ context.Context, handler func()) {
+	_, _ = ps.podInformer.Informer().AddEventHandler(eventHandlerFunc(handler))
 }
 
 func (ps *podSource) Endpoints(_ context.Context) ([]*endpoint.Endpoint, error) {

source/pod_test.go

@@ -23,9 +23,13 @@ import (
 	"testing"
 
 	log "github.com/sirupsen/logrus"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
 	"github.com/stretchr/testify/require"
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	corev1lister "k8s.io/client-go/listers/core/v1"
+	"k8s.io/client-go/tools/cache"
 
 	"sigs.k8s.io/external-dns/endpoint"
 	"sigs.k8s.io/external-dns/internal/testutils"
@@ -909,6 +913,39 @@ func TestPodSourceLogs(t *testing.T) {
 	}
 }
 
+func TestPodSource_AddEventHandler(t *testing.T) {
+	fakeInformer := new(fakePodInformer)
+	inf := testInformer{}
+	fakeInformer.On("Informer").Return(&inf)
+
+	pSource := &podSource{
+		podInformer: fakeInformer,
+	}
+
+	handlerCalled := false
+	handler := func() { handlerCalled = true }
+
+	pSource.AddEventHandler(t.Context(), handler)
+
+	fakeInformer.AssertNumberOfCalls(t, "Informer", 1)
+	assert.False(t, handlerCalled)
+	assert.Equal(t, 1, inf.times)
+}
+
+type fakePodInformer struct {
+	mock.Mock
+	informer cache.SharedIndexInformer
+}
+
+func (f *fakePodInformer) Informer() cache.SharedIndexInformer {
+	args := f.Called()
+	return args.Get(0).(cache.SharedIndexInformer)
+}
+
+func (f *fakePodInformer) Lister() corev1lister.PodLister {
+	return corev1lister.NewPodLister(f.Informer().GetIndexer())
+}
+
 func nodesFixturesIPv6() []*corev1.Node {
 	return []*corev1.Node{
 		{