DRA resourceclaims: maintain metric of total and allocated claims

These metrics can provide insights into ResourceClaim usage. The total count is
redundant because the apiserver also provides count of resources, but having it
in the same sub-system next to the count of allocated claims might be more
discoverable and helps monitor the controller itself.

pkg/controller/resourceclaim/controller.go

@@ -157,15 +157,15 @@ func NewController(
 	if _, err := claimInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
 		AddFunc: func(obj interface{}) {
 			logger.V(6).Info("new claim", "claimDump", obj)
-			ec.enqueueResourceClaim(logger, obj, false)
+			ec.enqueueResourceClaim(logger, nil, obj)
 		},
 		UpdateFunc: func(old, updated interface{}) {
 			logger.V(6).Info("updated claim", "claimDump", updated)
-			ec.enqueueResourceClaim(logger, updated, false)
+			ec.enqueueResourceClaim(logger, old, updated)
 		},
 		DeleteFunc: func(obj interface{}) {
 			logger.V(6).Info("deleted claim", "claimDump", obj)
-			ec.enqueueResourceClaim(logger, obj, true)
+			ec.enqueueResourceClaim(logger, obj, nil)
 		},
 	}); err != nil {
 		return nil, err
@@ -326,15 +326,48 @@ func (ec *Controller) podNeedsWork(pod *v1.Pod) (bool, string) {
 	return false, "nothing to do"
 }
 
-func (ec *Controller) enqueueResourceClaim(logger klog.Logger, obj interface{}, deleted bool) {
+func (ec *Controller) enqueueResourceClaim(logger klog.Logger, oldObj, newObj interface{}) {
-	if d, ok := obj.(cache.DeletedFinalStateUnknown); ok {
+	deleted := newObj != nil
-		obj = d.Obj
+	if d, ok := oldObj.(cache.DeletedFinalStateUnknown); ok {
+		oldObj = d.Obj
 	}
-	claim, ok := obj.(*resourceapi.ResourceClaim)
+	oldClaim, ok := oldObj.(*resourceapi.ResourceClaim)
-	if !ok {
+	if oldObj != nil && !ok {
+		return
+	}
+	newClaim, ok := newObj.(*resourceapi.ResourceClaim)
+	if newObj != nil && !ok {
 		return
 	}
 
+	// Maintain metrics based on what was observed.
+	switch {
+	case oldClaim == nil:
+		// Added.
+		metrics.NumResourceClaims.Inc()
+		if newClaim.Status.Allocation != nil {
+			metrics.NumAllocatedResourceClaims.Inc()
+		}
+	case newClaim == nil:
+		// Deleted.
+		metrics.NumResourceClaims.Dec()
+		if oldClaim.Status.Allocation != nil {
+			metrics.NumAllocatedResourceClaims.Dec()
+		}
+	default:
+		// Updated.
+		switch {
+		case oldClaim.Status.Allocation == nil && newClaim.Status.Allocation != nil:
+			metrics.NumAllocatedResourceClaims.Inc()
+		case oldClaim.Status.Allocation != nil && newClaim.Status.Allocation == nil:
+			metrics.NumAllocatedResourceClaims.Dec()
+		}
+	}
+
+	claim := newClaim
+	if claim == nil {
+		claim = oldClaim
+	}
 	if !deleted {
 		// When starting up, we have to check all claims to find those with
 		// stale pods in ReservedFor. During an update, a pod might get added

pkg/controller/resourceclaim/controller_test.go

@@ -17,13 +17,14 @@ limitations under the License.
 package resourceclaim
 
 import (
-	"context"
 	"errors"
 	"fmt"
 	"sort"
 	"sync"
 	"testing"
+	"time"
 
+	"github.com/onsi/gomega"
 	"github.com/stretchr/testify/assert"
 
 	v1 "k8s.io/api/core/v1"
@@ -38,7 +39,8 @@ import (
 	"k8s.io/component-base/metrics/testutil"
 	"k8s.io/klog/v2"
 	"k8s.io/kubernetes/pkg/controller"
-	ephemeralvolumemetrics "k8s.io/kubernetes/pkg/controller/resourceclaim/metrics"
+	"k8s.io/kubernetes/pkg/controller/resourceclaim/metrics"
+	"k8s.io/kubernetes/test/utils/ktesting"
 )
 
 var (
@@ -79,10 +81,6 @@ var (
 	}()
 )
 
-func init() {
-	klog.InitFlags(nil)
-}
-
 func TestSyncHandler(t *testing.T) {
 	tests := []struct {
 		name             string
@@ -366,8 +364,8 @@ func TestSyncHandler(t *testing.T) {
 	for _, tc := range tests {
 		// Run sequentially because of global logging and global metrics.
 		t.Run(tc.name, func(t *testing.T) {
-			ctx, cancel := context.WithCancel(context.Background())
+			tCtx := ktesting.Init(t)
-			defer cancel()
+			tCtx = ktesting.WithCancel(tCtx)
 
 			var objects []runtime.Object
 			for _, pod := range tc.pods {
@@ -392,19 +390,19 @@ func TestSyncHandler(t *testing.T) {
 			claimInformer := informerFactory.Resource().V1alpha3().ResourceClaims()
 			templateInformer := informerFactory.Resource().V1alpha3().ResourceClaimTemplates()
 
-			ec, err := NewController(klog.FromContext(ctx), fakeKubeClient, podInformer, claimInformer, templateInformer)
+			ec, err := NewController(klog.FromContext(tCtx), fakeKubeClient, podInformer, claimInformer, templateInformer)
 			if err != nil {
 				t.Fatalf("error creating ephemeral controller : %v", err)
 			}
 
 			// Ensure informers are up-to-date.
-			informerFactory.Start(ctx.Done())
+			informerFactory.Start(tCtx.Done())
 			stopInformers := func() {
-				cancel()
+				tCtx.Cancel("stopping informers")
 				informerFactory.Shutdown()
 			}
 			defer stopInformers()
-			informerFactory.WaitForCacheSync(ctx.Done())
+			informerFactory.WaitForCacheSync(tCtx.Done())
 
 			// Add claims that only exist in the mutation cache.
 			for _, claim := range tc.claimsInCache {
@@ -414,13 +412,13 @@ func TestSyncHandler(t *testing.T) {
 			// Simulate race: stop informers, add more pods that the controller doesn't know about.
 			stopInformers()
 			for _, pod := range tc.podsLater {
-				_, err := fakeKubeClient.CoreV1().Pods(pod.Namespace).Create(ctx, pod, metav1.CreateOptions{})
+				_, err := fakeKubeClient.CoreV1().Pods(pod.Namespace).Create(tCtx, pod, metav1.CreateOptions{})
 				if err != nil {
 					t.Fatalf("unexpected error while creating pod: %v", err)
 				}
 			}
 
-			err = ec.syncHandler(ctx, tc.key)
+			err = ec.syncHandler(tCtx, tc.key)
 			if err != nil && !tc.expectedError {
 				t.Fatalf("unexpected error while running handler: %v", err)
 			}
@@ -428,13 +426,13 @@ func TestSyncHandler(t *testing.T) {
 				t.Fatalf("unexpected success")
 			}
 
-			claims, err := fakeKubeClient.ResourceV1alpha3().ResourceClaims("").List(ctx, metav1.ListOptions{})
+			claims, err := fakeKubeClient.ResourceV1alpha3().ResourceClaims("").List(tCtx, metav1.ListOptions{})
 			if err != nil {
 				t.Fatalf("unexpected error while listing claims: %v", err)
 			}
 			assert.Equal(t, normalizeClaims(tc.expectedClaims), normalizeClaims(claims.Items))
 
-			pods, err := fakeKubeClient.CoreV1().Pods("").List(ctx, metav1.ListOptions{})
+			pods, err := fakeKubeClient.CoreV1().Pods("").List(tCtx, metav1.ListOptions{})
 			if err != nil {
 				t.Fatalf("unexpected error while listing pods: %v", err)
 			}
@@ -455,6 +453,95 @@ func TestSyncHandler(t *testing.T) {
 	}
 }
 
+func TestResourceClaimEventHandler(t *testing.T) {
+	tCtx := ktesting.Init(t)
+	tCtx = ktesting.WithCancel(tCtx)
+
+	fakeKubeClient := createTestClient()
+	setupMetrics()
+	informerFactory := informers.NewSharedInformerFactory(fakeKubeClient, controller.NoResyncPeriodFunc())
+	podInformer := informerFactory.Core().V1().Pods()
+	claimInformer := informerFactory.Resource().V1alpha3().ResourceClaims()
+	templateInformer := informerFactory.Resource().V1alpha3().ResourceClaimTemplates()
+	claimClient := fakeKubeClient.ResourceV1alpha3().ResourceClaims(testNamespace)
+
+	_, err := NewController(tCtx.Logger(), fakeKubeClient, podInformer, claimInformer, templateInformer)
+	tCtx.ExpectNoError(err, "creating ephemeral controller")
+
+	informerFactory.Start(tCtx.Done())
+	stopInformers := func() {
+		tCtx.Cancel("stopping informers")
+		informerFactory.Shutdown()
+	}
+	defer stopInformers()
+
+	var em numMetrics
+
+	_, err = claimClient.Create(tCtx, testClaim, metav1.CreateOptions{})
+	em.claims++
+	ktesting.Step(tCtx, "create claim", func(tCtx ktesting.TContext) {
+		tCtx.ExpectNoError(err)
+		em.Eventually(tCtx)
+	})
+
+	modifiedClaim := testClaim.DeepCopy()
+	modifiedClaim.Labels = map[string]string{"foo": "bar"}
+	_, err = claimClient.Update(tCtx, modifiedClaim, metav1.UpdateOptions{})
+	ktesting.Step(tCtx, "modify claim", func(tCtx ktesting.TContext) {
+		tCtx.ExpectNoError(err)
+		em.Consistently(tCtx)
+	})
+
+	_, err = claimClient.Update(tCtx, testClaimAllocated, metav1.UpdateOptions{})
+	em.allocated++
+	ktesting.Step(tCtx, "allocate claim", func(tCtx ktesting.TContext) {
+		tCtx.ExpectNoError(err)
+		em.Eventually(tCtx)
+	})
+
+	modifiedClaim = testClaimAllocated.DeepCopy()
+	modifiedClaim.Labels = map[string]string{"foo": "bar2"}
+	_, err = claimClient.Update(tCtx, modifiedClaim, metav1.UpdateOptions{})
+	ktesting.Step(tCtx, "modify claim", func(tCtx ktesting.TContext) {
+		tCtx.ExpectNoError(err)
+		em.Consistently(tCtx)
+	})
+
+	otherClaimAllocated := testClaimAllocated.DeepCopy()
+	otherClaimAllocated.Name += "2"
+	_, err = claimClient.Create(tCtx, otherClaimAllocated, metav1.CreateOptions{})
+	em.claims++
+	em.allocated++
+	ktesting.Step(tCtx, "create allocated claim", func(tCtx ktesting.TContext) {
+		tCtx.ExpectNoError(err)
+		em.Eventually(tCtx)
+	})
+
+	_, err = claimClient.Update(tCtx, testClaim, metav1.UpdateOptions{})
+	em.allocated--
+	ktesting.Step(tCtx, "deallocate claim", func(tCtx ktesting.TContext) {
+		tCtx.ExpectNoError(err)
+		em.Eventually(tCtx)
+	})
+
+	err = claimClient.Delete(tCtx, testClaim.Name, metav1.DeleteOptions{})
+	em.claims--
+	ktesting.Step(tCtx, "delete deallocated claim", func(tCtx ktesting.TContext) {
+		tCtx.ExpectNoError(err)
+		em.Eventually(tCtx)
+	})
+
+	err = claimClient.Delete(tCtx, otherClaimAllocated.Name, metav1.DeleteOptions{})
+	em.claims--
+	em.allocated--
+	ktesting.Step(tCtx, "delete allocated claim", func(tCtx ktesting.TContext) {
+		tCtx.ExpectNoError(err)
+		em.Eventually(tCtx)
+	})
+
+	em.Consistently(tCtx)
+}
+
 func makeClaim(name, namespace, classname string, owner *metav1.OwnerReference) *resourceapi.ResourceClaim {
 	claim := &resourceapi.ResourceClaim{
 		ObjectMeta: metav1.ObjectMeta{Name: name, Namespace: namespace},
@@ -596,6 +683,34 @@ func createResourceClaimReactor() func(action k8stesting.Action) (handled bool,
 
 // Metrics helpers
 
+type numMetrics struct {
+	claims    float64
+	allocated float64
+}
+
+func getNumMetric() (em numMetrics, err error) {
+	em.claims, err = testutil.GetGaugeMetricValue(metrics.NumResourceClaims)
+	if err != nil {
+		return
+	}
+	em.allocated, err = testutil.GetGaugeMetricValue(metrics.NumAllocatedResourceClaims)
+	return
+}
+
+func (em numMetrics) Eventually(tCtx ktesting.TContext) {
+	g := gomega.NewWithT(tCtx)
+	tCtx.Helper()
+
+	g.Eventually(getNumMetric).WithTimeout(5 * time.Second).Should(gomega.Equal(em))
+}
+
+func (em numMetrics) Consistently(tCtx ktesting.TContext) {
+	g := gomega.NewWithT(tCtx)
+	tCtx.Helper()
+
+	g.Consistently(getNumMetric).WithTimeout(time.Second).Should(gomega.Equal(em))
+}
+
 type expectedMetrics struct {
 	numCreated  int
 	numFailures int
@@ -604,12 +719,12 @@ type expectedMetrics struct {
 func expectMetrics(t *testing.T, em expectedMetrics) {
 	t.Helper()
 
-	actualCreated, err := testutil.GetCounterMetricValue(ephemeralvolumemetrics.ResourceClaimCreateAttempts)
+	actualCreated, err := testutil.GetCounterMetricValue(metrics.ResourceClaimCreateAttempts)
 	handleErr(t, err, "ResourceClaimCreate")
 	if actualCreated != float64(em.numCreated) {
 		t.Errorf("Expected claims to be created %d, got %v", em.numCreated, actualCreated)
 	}
-	actualConflicts, err := testutil.GetCounterMetricValue(ephemeralvolumemetrics.ResourceClaimCreateFailures)
+	actualConflicts, err := testutil.GetCounterMetricValue(metrics.ResourceClaimCreateFailures)
 	handleErr(t, err, "ResourceClaimCreate/Conflict")
 	if actualConflicts != float64(em.numFailures) {
 		t.Errorf("Expected claims to have conflicts %d, got %v", em.numFailures, actualConflicts)
@@ -623,7 +738,9 @@ func handleErr(t *testing.T, err error, metricName string) {
 }
 
 func setupMetrics() {
-	ephemeralvolumemetrics.RegisterMetrics()
+	metrics.RegisterMetrics()
-	ephemeralvolumemetrics.ResourceClaimCreateAttempts.Reset()
+	metrics.ResourceClaimCreateAttempts.Reset()
-	ephemeralvolumemetrics.ResourceClaimCreateFailures.Reset()
+	metrics.ResourceClaimCreateFailures.Reset()
+	metrics.NumResourceClaims.Set(0)
+	metrics.NumAllocatedResourceClaims.Set(0)
 }

pkg/controller/resourceclaim/metrics/metrics.go

@@ -45,6 +45,22 @@ var (
 			Help:           "Number of ResourceClaims creation request failures",
 			StabilityLevel: metrics.ALPHA,
 		})
+	// NumResourceClaims tracks the current number of ResourceClaims.
+	NumResourceClaims = metrics.NewGauge(
+		&metrics.GaugeOpts{
+			Subsystem:      ResourceClaimSubsystem,
+			Name:           "resource_claims",
+			Help:           "Number of ResourceClaims",
+			StabilityLevel: metrics.ALPHA,
+		})
+	// NumAllocatedResourceClaims tracks the current number of allocated ResourceClaims.
+	NumAllocatedResourceClaims = metrics.NewGauge(
+		&metrics.GaugeOpts{
+			Subsystem:      ResourceClaimSubsystem,
+			Name:           "allocated_resource_claims",
+			Help:           "Number of allocated ResourceClaims",
+			StabilityLevel: metrics.ALPHA,
+		})
 )
 
 var registerMetrics sync.Once
@@ -54,5 +70,7 @@ func RegisterMetrics() {
 	registerMetrics.Do(func() {
 		legacyregistry.MustRegister(ResourceClaimCreateAttempts)
 		legacyregistry.MustRegister(ResourceClaimCreateFailures)
+		legacyregistry.MustRegister(NumResourceClaims)
+		legacyregistry.MustRegister(NumAllocatedResourceClaims)
 	})
 }