Unregister events in schedulingGates plugin

Signed-off-by: kerthcet <kerthcet@gmail.com>

pkg/scheduler/framework/interface.go

@@ -370,6 +370,10 @@ type EnqueueExtensions interface {
 	// and leveraged to build event handlers dynamically.
 	// Note: the returned list needs to be static (not depend on configuration parameters);
 	// otherwise it would lead to undefined behavior.
+	//
+	// The returned events could be nil to indicate that no events other than the pod's own update
+	// can make the pod re-schedulable. An example is SchedulingGates plugin.
+	// Appropriate implementation of this function will make Pod's re-scheduling accurate and performant.
 	EventsToRegister() []ClusterEventWithHint
 }
 

pkg/scheduler/framework/plugins/schedulinggates/scheduling_gates.go

@@ -53,12 +53,10 @@ func (pl *SchedulingGates) PreEnqueue(ctx context.Context, p *v1.Pod) *framework
 	return framework.NewStatus(framework.UnschedulableAndUnresolvable, fmt.Sprintf("waiting for scheduling gates: %v", gates))
 }
 
-// EventsToRegister returns the possible events that may make a Pod
-// failed by this plugin schedulable.
+// EventsToRegister returns nil here to indicate that schedulingGates plugin is not
+// interested in any event but its own update.
 func (pl *SchedulingGates) EventsToRegister() []framework.ClusterEventWithHint {
-	return []framework.ClusterEventWithHint{
-		{Event: framework.ClusterEvent{Resource: framework.Pod, ActionType: framework.Update}},
-	}
+	return nil
 }
 
 // New initializes a new plugin and returns it.

pkg/scheduler/scheduler.go

@@ -373,6 +373,13 @@ func buildQueueingHintMap(es []framework.EnqueueExtensions) internalqueue.Queuei
 	for _, e := range es {
 		events := e.EventsToRegister()
 
+		// This will happen when plugin registers with empty events, it's usually the case a pod
+		// will become reschedulable only for self-update, e.g. schedulingGates plugin, the pod
+		// will enter into the activeQ via priorityQueue.Update().
+		if len(events) == 0 {
+			continue
+		}
+
 		// Note: Rarely, a plugin implements EnqueueExtensions but returns nil.
 		// We treat it as: the plugin is not interested in any event, and hence pod failed by that plugin
 		// cannot be moved by any regular cluster event.

pkg/scheduler/scheduler_test.go

@@ -662,6 +662,7 @@ const (
 	emptyEventsToRegister          = "emptyEventsToRegister"
 	queueSort                      = "no-op-queue-sort-plugin"
 	fakeBind                       = "bind-plugin"
+	emptyEventExtensions           = "emptyEventExtensions"
 )
 
 func Test_buildQueueingHintMap(t *testing.T) {
@@ -729,6 +730,23 @@ func Test_buildQueueingHintMap(t *testing.T) {
 				},
 			},
 		},
+		{
+			name:    "register plugin with empty event",
+			plugins: []framework.Plugin{&emptyEventPlugin{}},
+			want:    map[framework.ClusterEvent][]*internalqueue.QueueingHintFunction{},
+		},
+		{
+			name:    "register plugins including emptyEventPlugin",
+			plugins: []framework.Plugin{&emptyEventPlugin{}, &fakeNodePlugin{}},
+			want: map[framework.ClusterEvent][]*internalqueue.QueueingHintFunction{
+				{Resource: framework.Pod, ActionType: framework.Add}: {
+					{PluginName: fakePod, QueueingHintFn: fakePodPluginQueueingFn},
+				},
+				{Resource: framework.Node, ActionType: framework.Add}: {
+					{PluginName: fakeNode, QueueingHintFn: fakeNodePluginQueueingFn},
+				},
+			},
+		},
 	}
 
 	for _, tt := range tests {
@@ -1009,6 +1027,18 @@ func (pl *fakePodPlugin) EventsToRegister() []framework.ClusterEventWithHint {
 	}
 }
 
+type emptyEventPlugin struct{}
+
+func (*emptyEventPlugin) Name() string { return emptyEventExtensions }
+
+func (*emptyEventPlugin) Filter(_ context.Context, _ *framework.CycleState, _ *v1.Pod, _ *framework.NodeInfo) *framework.Status {
+	return nil
+}
+
+func (pl *emptyEventPlugin) EventsToRegister() []framework.ClusterEventWithHint {
+	return nil
+}
+
 // emptyEventsToRegisterPlugin implement interface framework.EnqueueExtensions, but returns nil from EventsToRegister.
 // This can simulate a plugin registered at scheduler setup, but does nothing
 // due to some disabled feature gate.

test/integration/scheduler/plugins/plugins_test.go

@@ -45,6 +45,7 @@ import (
 	"k8s.io/kubernetes/pkg/scheduler/framework"
 	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/defaultbinder"
 	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/noderesources"
+	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/schedulinggates"
 	frameworkruntime "k8s.io/kubernetes/pkg/scheduler/framework/runtime"
 	st "k8s.io/kubernetes/pkg/scheduler/testing"
 	schedulerutils "k8s.io/kubernetes/test/integration/scheduler"
@@ -2588,3 +2589,197 @@ func TestActivatePods(t *testing.T) {
 		t.Errorf("JobPlugin's pods activation logic is not called")
 	}
 }
+
+var _ framework.PreEnqueuePlugin = &SchedulingGatesPluginWithEvents{}
+var _ framework.EnqueueExtensions = &SchedulingGatesPluginWithEvents{}
+var _ framework.PreEnqueuePlugin = &SchedulingGatesPluginWOEvents{}
+var _ framework.EnqueueExtensions = &SchedulingGatesPluginWOEvents{}
+
+const (
+	schedulingGatesPluginWithEvents = "scheduling-gates-with-events"
+	schedulingGatesPluginWOEvents   = "scheduling-gates-without-events"
+)
+
+type SchedulingGatesPluginWithEvents struct {
+	called int
+	schedulinggates.SchedulingGates
+}
+
+func (pl *SchedulingGatesPluginWithEvents) Name() string {
+	return schedulingGatesPluginWithEvents
+}
+
+func (pl *SchedulingGatesPluginWithEvents) PreEnqueue(ctx context.Context, p *v1.Pod) *framework.Status {
+	pl.called++
+	return pl.SchedulingGates.PreEnqueue(ctx, p)
+}
+
+func (pl *SchedulingGatesPluginWithEvents) EventsToRegister() []framework.ClusterEventWithHint {
+	return []framework.ClusterEventWithHint{
+		{Event: framework.ClusterEvent{Resource: framework.Pod, ActionType: framework.Update}},
+	}
+}
+
+type SchedulingGatesPluginWOEvents struct {
+	called int
+	schedulinggates.SchedulingGates
+}
+
+func (pl *SchedulingGatesPluginWOEvents) Name() string {
+	return schedulingGatesPluginWOEvents
+}
+
+func (pl *SchedulingGatesPluginWOEvents) PreEnqueue(ctx context.Context, p *v1.Pod) *framework.Status {
+	pl.called++
+	return pl.SchedulingGates.PreEnqueue(ctx, p)
+}
+
+func (pl *SchedulingGatesPluginWOEvents) EventsToRegister() []framework.ClusterEventWithHint {
+	return nil
+}
+
+// This test helps to verify registering nil events for schedulingGates plugin works as expected.
+func TestSchedulingGatesPluginEventsToRegister(t *testing.T) {
+	defer featuregatetesting.SetFeatureGateDuringTest(t, feature.DefaultFeatureGate, features.PodSchedulingReadiness, true)()
+
+	testContext := testutils.InitTestAPIServer(t, "preenqueue-plugin", nil)
+
+	num := func(pl framework.Plugin) int {
+		switch item := pl.(type) {
+		case *SchedulingGatesPluginWithEvents:
+			return item.called
+		case *SchedulingGatesPluginWOEvents:
+			return item.called
+		default:
+			t.Error("unsupported plugin")
+		}
+		return 0
+	}
+
+	tests := []struct {
+		name          string
+		enqueuePlugin framework.PreEnqueuePlugin
+		count         int
+	}{
+		{
+			name:          "preEnqueue plugin without event registered",
+			enqueuePlugin: &SchedulingGatesPluginWOEvents{SchedulingGates: schedulinggates.SchedulingGates{EnablePodSchedulingReadiness: true}},
+			count:         2,
+		},
+		{
+			name:          "preEnqueue plugin with event registered",
+			enqueuePlugin: &SchedulingGatesPluginWithEvents{SchedulingGates: schedulinggates.SchedulingGates{EnablePodSchedulingReadiness: true}},
+			count:         3,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			registry := frameworkruntime.Registry{
+				tt.enqueuePlugin.Name(): newPlugin(tt.enqueuePlugin),
+			}
+
+			// Setup plugins for testing.
+			cfg := configtesting.V1ToInternalWithDefaults(t, configv1.KubeSchedulerConfiguration{
+				Profiles: []configv1.KubeSchedulerProfile{{
+					SchedulerName: pointer.String(v1.DefaultSchedulerName),
+					Plugins: &configv1.Plugins{
+						PreEnqueue: configv1.PluginSet{
+							Enabled: []configv1.Plugin{
+								{Name: tt.enqueuePlugin.Name()},
+							},
+							Disabled: []configv1.Plugin{
+								{Name: "*"},
+							},
+						},
+					},
+				}},
+			})
+
+			testCtx, teardown := schedulerutils.InitTestSchedulerForFrameworkTest(t, testContext, 2,
+				scheduler.WithProfiles(cfg.Profiles...),
+				scheduler.WithFrameworkOutOfTreeRegistry(registry),
+			)
+			defer teardown()
+
+			// Create a pod with schedulingGates.
+			gatedPod := st.MakePod().Name("p").Namespace(testContext.NS.Name).
+				SchedulingGates([]string{"foo"}).
+				PodAffinity("kubernetes.io/hostname", &metav1.LabelSelector{MatchLabels: map[string]string{"foo": "bar"}}, st.PodAffinityWithRequiredReq).
+				Container("pause").Obj()
+			gatedPod, err := testutils.CreatePausePod(testCtx.ClientSet, gatedPod)
+			if err != nil {
+				t.Errorf("Error while creating a gated pod: %v", err)
+				return
+			}
+
+			if err := testutils.WaitForPodSchedulingGated(testCtx.ClientSet, gatedPod, 10*time.Second); err != nil {
+				t.Errorf("Expected the pod to be gated, but got: %v", err)
+				return
+			}
+			if num(tt.enqueuePlugin) != 1 {
+				t.Errorf("Expected the preEnqueue plugin to be called once, but got %v", num(tt.enqueuePlugin))
+				return
+			}
+
+			// Create a best effort pod.
+			pausePod, err := testutils.CreatePausePod(testCtx.ClientSet, testutils.InitPausePod(&testutils.PausePodConfig{
+				Name:      "pause-pod",
+				Namespace: testCtx.NS.Name,
+				Labels:    map[string]string{"foo": "bar"},
+			}))
+			if err != nil {
+				t.Errorf("Error while creating a pod: %v", err)
+				return
+			}
+
+			// Wait for the pod schedulabled.
+			if err := testutils.WaitForPodToScheduleWithTimeout(testCtx.ClientSet, pausePod, 10*time.Second); err != nil {
+				t.Errorf("Expected the pod to be schedulable, but got: %v", err)
+				return
+			}
+
+			// Update the pod which will trigger the requeue logic if plugin registers the events.
+			pausePod, err = testCtx.ClientSet.CoreV1().Pods(pausePod.Namespace).Get(testCtx.Ctx, pausePod.Name, metav1.GetOptions{})
+			if err != nil {
+				t.Errorf("Error while getting a pod: %v", err)
+				return
+			}
+			pausePod.Annotations = map[string]string{"foo": "bar"}
+			_, err = testCtx.ClientSet.CoreV1().Pods(pausePod.Namespace).Update(testCtx.Ctx, pausePod, metav1.UpdateOptions{})
+			if err != nil {
+				t.Errorf("Error while updating a pod: %v", err)
+				return
+			}
+
+			// Pod should still be unschedulable because scheduling gates still exist, theoretically, it's a waste rescheduling.
+			if err := testutils.WaitForPodSchedulingGated(testCtx.ClientSet, gatedPod, 10*time.Second); err != nil {
+				t.Errorf("Expected the pod to be gated, but got: %v", err)
+				return
+			}
+			if num(tt.enqueuePlugin) != tt.count {
+				t.Errorf("Expected the preEnqueue plugin to be called %v, but got %v", tt.count, num(tt.enqueuePlugin))
+				return
+			}
+
+			// Remove gated pod's scheduling gates.
+			gatedPod, err = testCtx.ClientSet.CoreV1().Pods(gatedPod.Namespace).Get(testCtx.Ctx, gatedPod.Name, metav1.GetOptions{})
+			if err != nil {
+				t.Errorf("Error while getting a pod: %v", err)
+				return
+			}
+			gatedPod.Spec.SchedulingGates = nil
+			_, err = testCtx.ClientSet.CoreV1().Pods(gatedPod.Namespace).Update(testCtx.Ctx, gatedPod, metav1.UpdateOptions{})
+			if err != nil {
+				t.Errorf("Error while updating a pod: %v", err)
+				return
+			}
+
+			// Ungated pod should be schedulable now.
+			if err := testutils.WaitForPodToScheduleWithTimeout(testCtx.ClientSet, gatedPod, 10*time.Second); err != nil {
+				t.Errorf("Expected the pod to be schedulable, but got: %v", err)
+				return
+			}
+		})
+	}
+}