Use go-cmp to compare pods to suppress duplicate updates

Rather than copying the pods, this uses go-cmp and filters out
the paths which should not be compared.

node/podcontroller.go

@@ -17,10 +17,10 @@ package node
 import (
 	"context"
 	"fmt"
-	"reflect"
 	"strconv"
 	"sync"
 
+	"github.com/google/go-cmp/cmp"
 	pkgerrors "github.com/pkg/errors"
 	"github.com/virtual-kubelet/virtual-kubelet/errdefs"
 	"github.com/virtual-kubelet/virtual-kubelet/internal/manager"
@@ -241,14 +241,11 @@ func (pc *PodController) Run(ctx context.Context, podSyncWorkers int) (retErr er
 		},
 		UpdateFunc: func(oldObj, newObj interface{}) {
 			// Create a copy of the old and new pod objects so we don't mutate the cache.
-			oldPod := oldObj.(*corev1.Pod).DeepCopy()
+			oldPod := oldObj.(*corev1.Pod)
-			newPod := newObj.(*corev1.Pod).DeepCopy()
+			newPod := newObj.(*corev1.Pod)
-			// We want to check if the two objects differ in anything other than their resource versions.
-			// Hence, we make them equal so that this change isn't picked up by reflect.DeepEqual.
-			newPod.ResourceVersion = oldPod.ResourceVersion
 			// Skip adding this pod's key to the work queue if its .metadata (except .metadata.resourceVersion) and .spec fields haven't changed.
 			// This guarantees that we don't attempt to sync the pod every time its .status field is updated.
-			if reflect.DeepEqual(oldPod.ObjectMeta, newPod.ObjectMeta) && reflect.DeepEqual(oldPod.Spec, newPod.Spec) {
+			if podsEffectivelyEqual(oldPod, newPod) {
 				return
 			}
 			// At this point we know that something in .metadata or .spec has changed, so we must proceed to sync the pod.
@@ -503,3 +500,18 @@ func loggablePodName(pod *corev1.Pod) string {
 func loggablePodNameFromCoordinates(namespace, name string) string {
 	return fmt.Sprintf("%s/%s", namespace, name)
 }
+
+// podsEffectivelyEqual compares two pods, and ignores the pod status, and the resource version
+func podsEffectivelyEqual(p1, p2 *corev1.Pod) bool {
+	filterForResourceVersion := func(p cmp.Path) bool {
+		if p.String() == "ObjectMeta.ResourceVersion" {
+			return true
+		}
+		if p.String() == "Status" {
+			return true
+		}
+		return false
+	}
+
+	return cmp.Equal(p1, p2, cmp.FilterPath(filterForResourceVersion, cmp.Ignore()))
+}

node/podcontroller_test.go

@@ -6,6 +6,8 @@ import (
 	"time"
 
 	"gotest.tools/assert"
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
 func TestPodControllerExitOnContextCancel(t *testing.T) {
@@ -42,3 +44,49 @@ func TestPodControllerExitOnContextCancel(t *testing.T) {
 	}
 	assert.NilError(t, tc.Err())
 }
+
+func TestCompareResourceVersion(t *testing.T) {
+	p1 := &corev1.Pod{
+		ObjectMeta: metav1.ObjectMeta{
+			ResourceVersion: "1",
+		},
+	}
+	p2 := &corev1.Pod{
+		ObjectMeta: metav1.ObjectMeta{
+			ResourceVersion: "2",
+		},
+	}
+	assert.Assert(t, podsEffectivelyEqual(p1, p2))
+}
+
+func TestCompareStatus(t *testing.T) {
+	p1 := &corev1.Pod{
+		Status: corev1.PodStatus{
+			Phase: corev1.PodRunning,
+		},
+	}
+	p2 := &corev1.Pod{
+		Status: corev1.PodStatus{
+			Phase: corev1.PodFailed,
+		},
+	}
+	assert.Assert(t, podsEffectivelyEqual(p1, p2))
+}
+
+func TestCompareLabels(t *testing.T) {
+	p1 := &corev1.Pod{
+		ObjectMeta: metav1.ObjectMeta{
+			Labels: map[string]string{
+				"foo": "bar1",
+			},
+		},
+	}
+	p2 := &corev1.Pod{
+		ObjectMeta: metav1.ObjectMeta{
+			Labels: map[string]string{
+				"foo": "bar2",
+			},
+		},
+	}
+	assert.Assert(t, !podsEffectivelyEqual(p1, p2))
+}