Deep copying EndpointSlices in reconciler before modifying them.

pkg/controller/endpointslice/endpointslice_controller_test.go

@@ -18,6 +18,7 @@ package endpointslice
 
 import (
 	"fmt"
+	"reflect"
 	"testing"
 	"time"
 
@@ -25,6 +26,7 @@ import (
 	v1 "k8s.io/api/core/v1"
 	discovery "k8s.io/api/discovery/v1beta1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/intstr"
 	"k8s.io/client-go/informers"
 	"k8s.io/client-go/kubernetes/fake"
@@ -239,6 +241,8 @@ func TestSyncServiceEndpointSliceLabelSelection(t *testing.T) {
 		AddressType: discovery.AddressTypeIPv4,
 	}}
 
+	cmc := newCacheMutationCheck(endpointSlices)
+
 	// need to add them to both store and fake clientset
 	for _, endpointSlice := range endpointSlices {
 		err := esController.endpointSliceStore.Add(endpointSlice)
@@ -262,6 +266,9 @@ func TestSyncServiceEndpointSliceLabelSelection(t *testing.T) {
 	// only 2 slices should match, 2 should be deleted, 1 should be updated as a placeholder
 	expectAction(t, client.Actions(), numActionsBefore, "update", "endpointslices")
 	expectAction(t, client.Actions(), numActionsBefore+1, "delete", "endpointslices")
+
+	// ensure cache mutation has not occurred
+	cmc.Check(t)
 }
 
 // Ensure SyncService handles a variety of protocols and IPs appropriately.
@@ -316,17 +323,17 @@ func TestSyncServiceFull(t *testing.T) {
 	assert.Len(t, slice.Endpoints, 1, "Expected 1 endpoints in first slice")
 	assert.Equal(t, slice.Annotations["endpoints.kubernetes.io/last-change-trigger-time"], serviceCreateTime.Format(time.RFC3339Nano))
 	assert.EqualValues(t, []discovery.EndpointPort{{
-		Name:     strPtr("sctp-example"),
+		Name:     utilpointer.StringPtr("sctp-example"),
 		Protocol: protoPtr(v1.ProtocolSCTP),
-		Port:     int32Ptr(int32(3456)),
+		Port:     utilpointer.Int32Ptr(int32(3456)),
 	}, {
-		Name:     strPtr("udp-example"),
+		Name:     utilpointer.StringPtr("udp-example"),
 		Protocol: protoPtr(v1.ProtocolUDP),
-		Port:     int32Ptr(int32(161)),
+		Port:     utilpointer.Int32Ptr(int32(161)),
 	}, {
-		Name:     strPtr("tcp-example"),
+		Name:     utilpointer.StringPtr("tcp-example"),
 		Protocol: protoPtr(v1.ProtocolTCP),
-		Port:     int32Ptr(int32(80)),
+		Port:     utilpointer.Int32Ptr(int32(80)),
 	}}, slice.Ports)
 
 	assert.ElementsMatch(t, []discovery.Endpoint{{
@@ -382,14 +389,49 @@ func expectAction(t *testing.T, actions []k8stesting.Action, index int, verb, re
 	}
 }
 
-func strPtr(str string) *string {
+// protoPtr takes a Protocol and returns a pointer to it.
-	return &str
-}
-
 func protoPtr(proto v1.Protocol) *v1.Protocol {
 	return &proto
 }
 
-func int32Ptr(num int32) *int32 {
+// cacheMutationCheck helps ensure that cached objects have not been changed
-	return &num
+// in any way throughout a test run.
+type cacheMutationCheck struct {
+	objects []cacheObject
+}
+
+// cacheObject stores a reference to an original object as well as a deep copy
+// of that object to track any mutations in the original object.
+type cacheObject struct {
+	original runtime.Object
+	deepCopy runtime.Object
+}
+
+// newCacheMutationCheck initializes a cacheMutationCheck with EndpointSlices.
+func newCacheMutationCheck(endpointSlices []*discovery.EndpointSlice) cacheMutationCheck {
+	cmc := cacheMutationCheck{}
+	for _, endpointSlice := range endpointSlices {
+		cmc.Add(endpointSlice)
+	}
+	return cmc
+}
+
+// Add appends a runtime.Object and a deep copy of that object into the
+// cacheMutationCheck.
+func (cmc *cacheMutationCheck) Add(o runtime.Object) {
+	cmc.objects = append(cmc.objects, cacheObject{
+		original: o,
+		deepCopy: o.DeepCopyObject(),
+	})
+}
+
+// Check verifies that no objects in the cacheMutationCheck have been mutated.
+func (cmc *cacheMutationCheck) Check(t *testing.T) {
+	for _, o := range cmc.objects {
+		if !reflect.DeepEqual(o.original, o.deepCopy) {
+			// Cached objects can't be safely mutated and instead should be deep
+			// copied before changed in any way.
+			t.Errorf("Cached object was unexpectedly mutated. Original: %+v, Mutated: %+v", o.deepCopy, o.original)
+		}
+	}
 }

pkg/controller/endpointslice/reconciler.go

@@ -290,9 +290,11 @@ func (r *reconciler) reconcileByPortMapping(
 				// if no endpoints desired in this slice, mark for deletion
 				sliceNamesToDelete.Insert(existingSlice.Name)
 			} else {
-				// otherwise, mark for update
+				// otherwise, copy and mark for update
-				existingSlice.Endpoints = newEndpoints
+				epSlice := existingSlice.DeepCopy()
-				sliceNamesToUpdate.Insert(existingSlice.Name)
+				epSlice.Endpoints = newEndpoints
+				slicesByName[existingSlice.Name] = epSlice
+				sliceNamesToUpdate.Insert(epSlice.Name)
 			}
 		} else {
 			// slices with no changes will be useful if there are leftover endpoints
@@ -344,6 +346,10 @@ func (r *reconciler) reconcileByPortMapping(
 		// If we didn't find a sliceToFill, generate a new empty one.
 		if sliceToFill == nil {
 			sliceToFill = newEndpointSlice(service, endpointMeta)
+		} else {
+			// deep copy required to modify this slice.
+			sliceToFill = sliceToFill.DeepCopy()
+			slicesByName[sliceToFill.Name] = sliceToFill
 		}
 
 		// Fill the slice up with remaining endpoints.

pkg/controller/endpointslice/reconciler_test.go

@@ -318,6 +318,7 @@ func TestReconcileEndpointSlicesSomePreexisting(t *testing.T) {
 	}
 
 	existingSlices := []*discovery.EndpointSlice{endpointSlice1, endpointSlice2}
+	cmc := newCacheMutationCheck(existingSlices)
 	createEndpointSlices(t, client, namespace, existingSlices)
 
 	numActionsBefore := len(client.Actions())
@@ -332,6 +333,9 @@ func TestReconcileEndpointSlicesSomePreexisting(t *testing.T) {
 	// 1 new slice (0->100) + 1 updated slice (62->89)
 	expectUnorderedSlicesWithLengths(t, fetchEndpointSlices(t, client, namespace), []int{89, 61, 100})
 	expectMetrics(t, expectedMetrics{desiredSlices: 3, actualSlices: 3, desiredEndpoints: 250, addedPerSync: 127, removedPerSync: 0, numCreated: 1, numUpdated: 1, numDeleted: 0})
+
+	// ensure cache mutation has not occurred
+	cmc.Check(t)
 }
 
 // now with preexisting slices, we have 300 pods matching a service
@@ -370,6 +374,7 @@ func TestReconcileEndpointSlicesSomePreexistingWorseAllocation(t *testing.T) {
 	}
 
 	existingSlices := []*discovery.EndpointSlice{endpointSlice1, endpointSlice2}
+	cmc := newCacheMutationCheck(existingSlices)
 	createEndpointSlices(t, client, namespace, existingSlices)
 
 	numActionsBefore := len(client.Actions())
@@ -383,6 +388,9 @@ func TestReconcileEndpointSlicesSomePreexistingWorseAllocation(t *testing.T) {
 	// 2 new slices (100, 52) in addition to existing slices (74, 74)
 	expectUnorderedSlicesWithLengths(t, fetchEndpointSlices(t, client, namespace), []int{74, 74, 100, 52})
 	expectMetrics(t, expectedMetrics{desiredSlices: 3, actualSlices: 4, desiredEndpoints: 300, addedPerSync: 152, removedPerSync: 0, numCreated: 2, numUpdated: 0, numDeleted: 0})
+
+	// ensure cache mutation has not occurred
+	cmc.Check(t)
 }
 
 // In some cases, such as a service port change, all slices for that service will require a change
@@ -445,6 +453,7 @@ func TestReconcileEndpointSlicesRecycling(t *testing.T) {
 		existingSlices[sliceNum].Endpoints = append(existingSlices[sliceNum].Endpoints, podToEndpoint(pod, &corev1.Node{}, &svc))
 	}
 
+	cmc := newCacheMutationCheck(existingSlices)
 	createEndpointSlices(t, client, namespace, existingSlices)
 
 	numActionsBefore := len(client.Actions())
@@ -463,6 +472,9 @@ func TestReconcileEndpointSlicesRecycling(t *testing.T) {
 	// thanks to recycling, we get a free repack of endpoints, resulting in 3 full slices instead of 10 mostly empty slices
 	expectUnorderedSlicesWithLengths(t, fetchEndpointSlices(t, client, namespace), []int{100, 100, 100})
 	expectMetrics(t, expectedMetrics{desiredSlices: 3, actualSlices: 3, desiredEndpoints: 300, addedPerSync: 300, removedPerSync: 0, numCreated: 0, numUpdated: 3, numDeleted: 7})
+
+	// ensure cache mutation has not occurred
+	cmc.Check(t)
 }
 
 // In this test, we want to verify that endpoints are added to a slice that will
@@ -493,6 +505,7 @@ func TestReconcileEndpointSlicesUpdatePacking(t *testing.T) {
 	}
 	existingSlices = append(existingSlices, slice2)
 
+	cmc := newCacheMutationCheck(existingSlices)
 	createEndpointSlices(t, client, namespace, existingSlices)
 
 	// ensure that endpoints in each slice will be marked for update.
@@ -519,6 +532,9 @@ func TestReconcileEndpointSlicesUpdatePacking(t *testing.T) {
 
 	// additional pods should get added to fuller slice
 	expectUnorderedSlicesWithLengths(t, fetchEndpointSlices(t, client, namespace), []int{95, 20})
+
+	// ensure cache mutation has not occurred
+	cmc.Check(t)
 }
 
 // In this test, we want to verify that old EndpointSlices with a deprecated IP
@@ -552,6 +568,7 @@ func TestReconcileEndpointSlicesReplaceDeprecated(t *testing.T) {
 
 	createEndpointSlices(t, client, namespace, existingSlices)
 
+	cmc := newCacheMutationCheck(existingSlices)
 	r := newReconciler(client, []*corev1.Node{{ObjectMeta: metav1.ObjectMeta{Name: "node-1"}}}, defaultMaxEndpointsPerSlice)
 	reconcileHelper(t, r, &svc, pods, existingSlices, time.Now())
 
@@ -569,6 +586,9 @@ func TestReconcileEndpointSlicesReplaceDeprecated(t *testing.T) {
 			t.Errorf("Expected address type to be IPv4, got %s", endpointSlice.AddressType)
 		}
 	}
+
+	// ensure cache mutation has not occurred
+	cmc.Check(t)
 }
 
 // Named ports can map to different port numbers on different pods.