custom-kube-scheduler/kubernetes/test/integration/scheduler/taint_test.go

/*
Copyright 2017 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package scheduler

// This file tests the Taint feature.

import (
	"context"
	"errors"
	"fmt"
	"testing"
	"time"

	v1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/api/resource"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/apiserver/pkg/admission"
	utilfeature "k8s.io/apiserver/pkg/util/feature"
	"k8s.io/client-go/informers"
	"k8s.io/client-go/kubernetes"
	restclient "k8s.io/client-go/rest"
	featuregatetesting "k8s.io/component-base/featuregate/testing"
	"k8s.io/kubernetes/pkg/controller/nodelifecycle"
	"k8s.io/kubernetes/pkg/features"
	"k8s.io/kubernetes/plugin/pkg/admission/defaulttolerationseconds"
	"k8s.io/kubernetes/plugin/pkg/admission/podtolerationrestriction"
	pluginapi "k8s.io/kubernetes/plugin/pkg/admission/podtolerationrestriction/apis/podtolerationrestriction"
	"k8s.io/kubernetes/test/e2e/framework/pod"
	imageutils "k8s.io/kubernetes/test/utils/image"
)

func newPod(nsName, name string, req, limit v1.ResourceList) *v1.Pod {
	return &v1.Pod{
		ObjectMeta: metav1.ObjectMeta{
			Name:      name,
			Namespace: nsName,
		},
		Spec: v1.PodSpec{
			Containers: []v1.Container{
				{
					Name:  "busybox",
					Image: "busybox",
					Resources: v1.ResourceRequirements{
						Requests: req,
						Limits:   limit,
					},
				},
			},
		},
	}
}

// TestTaintNodeByCondition tests related cases for TaintNodeByCondition feature.
func TestTaintNodeByCondition(t *testing.T) {
	// Build PodToleration Admission.
	admission := podtolerationrestriction.NewPodTolerationsPlugin(&pluginapi.Configuration{})

	testCtx := initTestMaster(t, "default", admission)

	// Build clientset and informers for controllers.
	externalClientset := kubernetes.NewForConfigOrDie(&restclient.Config{
		QPS:           -1,
		Host:          testCtx.httpServer.URL,
		ContentConfig: restclient.ContentConfig{GroupVersion: &schema.GroupVersion{Group: "", Version: "v1"}}})
	externalInformers := informers.NewSharedInformerFactory(externalClientset, time.Second)

	admission.SetExternalKubeClientSet(externalClientset)
	admission.SetExternalKubeInformerFactory(externalInformers)

	testCtx = initTestScheduler(t, testCtx, false, nil)
	defer cleanupTest(t, testCtx)

	cs := testCtx.clientSet
	informers := testCtx.informerFactory
	nsName := testCtx.ns.Name

	// Start NodeLifecycleController for taint.
	nc, err := nodelifecycle.NewNodeLifecycleController(
		informers.Coordination().V1().Leases(),
		informers.Core().V1().Pods(),
		informers.Core().V1().Nodes(),
		informers.Apps().V1().DaemonSets(),
		cs,
		time.Hour,   // Node monitor grace period
		time.Second, // Node startup grace period
		time.Second, // Node monitor period
		time.Second, // Pod eviction timeout
		100,         // Eviction limiter QPS
		100,         // Secondary eviction limiter QPS
		100,         // Large cluster threshold
		100,         // Unhealthy zone threshold
		true,        // Run taint manager
		true,        // Use taint based evictions
	)
	if err != nil {
		t.Errorf("Failed to create node controller: %v", err)
		return
	}
	go nc.Run(testCtx.ctx.Done())

	// Waiting for all controller sync.
	externalInformers.Start(testCtx.ctx.Done())
	externalInformers.WaitForCacheSync(testCtx.ctx.Done())
	informers.Start(testCtx.ctx.Done())
	informers.WaitForCacheSync(testCtx.ctx.Done())

	// -------------------------------------------
	// Test TaintNodeByCondition feature.
	// -------------------------------------------
	nodeRes := v1.ResourceList{
		v1.ResourceCPU:    resource.MustParse("4000m"),
		v1.ResourceMemory: resource.MustParse("16Gi"),
		v1.ResourcePods:   resource.MustParse("110"),
	}

	podRes := v1.ResourceList{
		v1.ResourceCPU:    resource.MustParse("100m"),
		v1.ResourceMemory: resource.MustParse("100Mi"),
	}

	notReadyToleration := v1.Toleration{
		Key:      v1.TaintNodeNotReady,
		Operator: v1.TolerationOpExists,
		Effect:   v1.TaintEffectNoSchedule,
	}

	unschedulableToleration := v1.Toleration{
		Key:      v1.TaintNodeUnschedulable,
		Operator: v1.TolerationOpExists,
		Effect:   v1.TaintEffectNoSchedule,
	}

	memoryPressureToleration := v1.Toleration{
		Key:      v1.TaintNodeMemoryPressure,
		Operator: v1.TolerationOpExists,
		Effect:   v1.TaintEffectNoSchedule,
	}

	diskPressureToleration := v1.Toleration{
		Key:      v1.TaintNodeDiskPressure,
		Operator: v1.TolerationOpExists,
		Effect:   v1.TaintEffectNoSchedule,
	}

	networkUnavailableToleration := v1.Toleration{
		Key:      v1.TaintNodeNetworkUnavailable,
		Operator: v1.TolerationOpExists,
		Effect:   v1.TaintEffectNoSchedule,
	}

	pidPressureToleration := v1.Toleration{
		Key:      v1.TaintNodePIDPressure,
		Operator: v1.TolerationOpExists,
		Effect:   v1.TaintEffectNoSchedule,
	}

	bestEffortPod := newPod(nsName, "besteffort-pod", nil, nil)
	burstablePod := newPod(nsName, "burstable-pod", podRes, nil)
	guaranteePod := newPod(nsName, "guarantee-pod", podRes, podRes)

	type podCase struct {
		pod         *v1.Pod
		tolerations []v1.Toleration
		fits        bool
	}

	// switch to table driven testings
	tests := []struct {
		name           string
		existingTaints []v1.Taint
		nodeConditions []v1.NodeCondition
		unschedulable  bool
		expectedTaints []v1.Taint
		pods           []podCase
	}{
		{
			name: "not-ready node",
			nodeConditions: []v1.NodeCondition{
				{
					Type:   v1.NodeReady,
					Status: v1.ConditionFalse,
				},
			},
			expectedTaints: []v1.Taint{
				{
					Key:    v1.TaintNodeNotReady,
					Effect: v1.TaintEffectNoSchedule,
				},
			},
			pods: []podCase{
				{
					pod:  bestEffortPod,
					fits: false,
				},
				{
					pod:  burstablePod,
					fits: false,
				},
				{
					pod:  guaranteePod,
					fits: false,
				},
				{
					pod:         bestEffortPod,
					tolerations: []v1.Toleration{notReadyToleration},
					fits:        true,
				},
			},
		},
		{
			name:          "unschedulable node",
			unschedulable: true, // node.spec.unschedulable = true
			nodeConditions: []v1.NodeCondition{
				{
					Type:   v1.NodeReady,
					Status: v1.ConditionTrue,
				},
			},
			expectedTaints: []v1.Taint{
				{
					Key:    v1.TaintNodeUnschedulable,
					Effect: v1.TaintEffectNoSchedule,
				},
			},
			pods: []podCase{
				{
					pod:  bestEffortPod,
					fits: false,
				},
				{
					pod:  burstablePod,
					fits: false,
				},
				{
					pod:  guaranteePod,
					fits: false,
				},
				{
					pod:         bestEffortPod,
					tolerations: []v1.Toleration{unschedulableToleration},
					fits:        true,
				},
			},
		},
		{
			name: "memory pressure node",
			nodeConditions: []v1.NodeCondition{
				{
					Type:   v1.NodeMemoryPressure,
					Status: v1.ConditionTrue,
				},
				{
					Type:   v1.NodeReady,
					Status: v1.ConditionTrue,
				},
			},
			expectedTaints: []v1.Taint{
				{
					Key:    v1.TaintNodeMemoryPressure,
					Effect: v1.TaintEffectNoSchedule,
				},
			},
			// In MemoryPressure condition, both Burstable and Guarantee pods are scheduled;
			// BestEffort pod with toleration are also scheduled.
			pods: []podCase{
				{
					pod:  bestEffortPod,
					fits: false,
				},
				{
					pod:         bestEffortPod,
					tolerations: []v1.Toleration{memoryPressureToleration},
					fits:        true,
				},
				{
					pod:         bestEffortPod,
					tolerations: []v1.Toleration{diskPressureToleration},
					fits:        false,
				},
				{
					pod:  burstablePod,
					fits: true,
				},
				{
					pod:  guaranteePod,
					fits: true,
				},
			},
		},
		{
			name: "disk pressure node",
			nodeConditions: []v1.NodeCondition{
				{
					Type:   v1.NodeDiskPressure,
					Status: v1.ConditionTrue,
				},
				{
					Type:   v1.NodeReady,
					Status: v1.ConditionTrue,
				},
			},
			expectedTaints: []v1.Taint{
				{
					Key:    v1.TaintNodeDiskPressure,
					Effect: v1.TaintEffectNoSchedule,
				},
			},
			// In DiskPressure condition, only pods with toleration can be scheduled.
			pods: []podCase{
				{
					pod:  bestEffortPod,
					fits: false,
				},
				{
					pod:  burstablePod,
					fits: false,
				},
				{
					pod:  guaranteePod,
					fits: false,
				},
				{
					pod:         bestEffortPod,
					tolerations: []v1.Toleration{diskPressureToleration},
					fits:        true,
				},
				{
					pod:         bestEffortPod,
					tolerations: []v1.Toleration{memoryPressureToleration},
					fits:        false,
				},
			},
		},
		{
			name: "network unavailable and node is ready",
			nodeConditions: []v1.NodeCondition{
				{
					Type:   v1.NodeNetworkUnavailable,
					Status: v1.ConditionTrue,
				},
				{
					Type:   v1.NodeReady,
					Status: v1.ConditionTrue,
				},
			},
			expectedTaints: []v1.Taint{
				{
					Key:    v1.TaintNodeNetworkUnavailable,
					Effect: v1.TaintEffectNoSchedule,
				},
			},
			pods: []podCase{
				{
					pod:  bestEffortPod,
					fits: false,
				},
				{
					pod:  burstablePod,
					fits: false,
				},
				{
					pod:  guaranteePod,
					fits: false,
				},
				{
					pod: burstablePod,
					tolerations: []v1.Toleration{
						networkUnavailableToleration,
					},
					fits: true,
				},
			},
		},
		{
			name: "network unavailable and node is not ready",
			nodeConditions: []v1.NodeCondition{
				{
					Type:   v1.NodeNetworkUnavailable,
					Status: v1.ConditionTrue,
				},
				{
					Type:   v1.NodeReady,
					Status: v1.ConditionFalse,
				},
			},
			expectedTaints: []v1.Taint{
				{
					Key:    v1.TaintNodeNetworkUnavailable,
					Effect: v1.TaintEffectNoSchedule,
				},
				{
					Key:    v1.TaintNodeNotReady,
					Effect: v1.TaintEffectNoSchedule,
				},
			},
			pods: []podCase{
				{
					pod:  bestEffortPod,
					fits: false,
				},
				{
					pod:  burstablePod,
					fits: false,
				},
				{
					pod:  guaranteePod,
					fits: false,
				},
				{
					pod: burstablePod,
					tolerations: []v1.Toleration{
						networkUnavailableToleration,
					},
					fits: false,
				},
				{
					pod: burstablePod,
					tolerations: []v1.Toleration{
						networkUnavailableToleration,
						notReadyToleration,
					},
					fits: true,
				},
			},
		},
		{
			name: "pid pressure node",
			nodeConditions: []v1.NodeCondition{
				{
					Type:   v1.NodePIDPressure,
					Status: v1.ConditionTrue,
				},
				{
					Type:   v1.NodeReady,
					Status: v1.ConditionTrue,
				},
			},
			expectedTaints: []v1.Taint{
				{
					Key:    v1.TaintNodePIDPressure,
					Effect: v1.TaintEffectNoSchedule,
				},
			},
			pods: []podCase{
				{
					pod:  bestEffortPod,
					fits: false,
				},
				{
					pod:  burstablePod,
					fits: false,
				},
				{
					pod:  guaranteePod,
					fits: false,
				},
				{
					pod:         bestEffortPod,
					tolerations: []v1.Toleration{pidPressureToleration},
					fits:        true,
				},
			},
		},
		{
			name: "multi taints on node",
			nodeConditions: []v1.NodeCondition{
				{
					Type:   v1.NodePIDPressure,
					Status: v1.ConditionTrue,
				},
				{
					Type:   v1.NodeMemoryPressure,
					Status: v1.ConditionTrue,
				},
				{
					Type:   v1.NodeDiskPressure,
					Status: v1.ConditionTrue,
				},
				{
					Type:   v1.NodeReady,
					Status: v1.ConditionTrue,
				},
			},
			expectedTaints: []v1.Taint{
				{
					Key:    v1.TaintNodeDiskPressure,
					Effect: v1.TaintEffectNoSchedule,
				},
				{
					Key:    v1.TaintNodeMemoryPressure,
					Effect: v1.TaintEffectNoSchedule,
				},
				{
					Key:    v1.TaintNodePIDPressure,
					Effect: v1.TaintEffectNoSchedule,
				},
			},
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			node := &v1.Node{
				ObjectMeta: metav1.ObjectMeta{
					Name: "node-1",
				},
				Spec: v1.NodeSpec{
					Unschedulable: test.unschedulable,
					Taints:        test.existingTaints,
				},
				Status: v1.NodeStatus{
					Capacity:    nodeRes,
					Allocatable: nodeRes,
					Conditions:  test.nodeConditions,
				},
			}

			if _, err := cs.CoreV1().Nodes().Create(context.TODO(), node, metav1.CreateOptions{}); err != nil {
				t.Errorf("Failed to create node, err: %v", err)
			}
			if err := waitForNodeTaints(cs, node, test.expectedTaints); err != nil {
				node, err = cs.CoreV1().Nodes().Get(context.TODO(), node.Name, metav1.GetOptions{})
				if err != nil {
					t.Errorf("Failed to get node <%s>", node.Name)
				}

				t.Errorf("Failed to taint node <%s>, expected: %v, got: %v, err: %v", node.Name, test.expectedTaints, node.Spec.Taints, err)
			}

			var pods []*v1.Pod
			for i, p := range test.pods {
				pod := p.pod.DeepCopy()
				pod.Name = fmt.Sprintf("%s-%d", pod.Name, i)
				pod.Spec.Tolerations = p.tolerations

				createdPod, err := cs.CoreV1().Pods(pod.Namespace).Create(context.TODO(), pod, metav1.CreateOptions{})
				if err != nil {
					t.Fatalf("Failed to create pod %s/%s, error: %v",
						pod.Namespace, pod.Name, err)
				}

				pods = append(pods, createdPod)

				if p.fits {
					if err := waitForPodToSchedule(cs, createdPod); err != nil {
						t.Errorf("Failed to schedule pod %s/%s on the node, err: %v",
							pod.Namespace, pod.Name, err)
					}
				} else {
					if err := waitForPodUnschedulable(cs, createdPod); err != nil {
						t.Errorf("Unschedulable pod %s/%s gets scheduled on the node, err: %v",
							pod.Namespace, pod.Name, err)
					}
				}
			}

			cleanupPods(cs, t, pods)
			cleanupNodes(cs, t)
			waitForSchedulerCacheCleanup(testCtx.scheduler, t)
		})
	}
}

// TestTaintBasedEvictions tests related cases for the TaintBasedEvictions feature
func TestTaintBasedEvictions(t *testing.T) {
	// we need at least 2 nodes to prevent lifecycle manager from entering "fully-disrupted" mode
	nodeCount := 3
	zero := int64(0)
	gracePeriod := int64(1)
	heartbeatInternal := time.Second * 2
	testPod := &v1.Pod{
		ObjectMeta: metav1.ObjectMeta{Name: "testpod1", DeletionGracePeriodSeconds: &zero},
		Spec: v1.PodSpec{
			Containers: []v1.Container{
				{Name: "container", Image: imageutils.GetPauseImageName()},
			},
			Tolerations: []v1.Toleration{
				{
					Key:      v1.TaintNodeNotReady,
					Operator: v1.TolerationOpExists,
					Effect:   v1.TaintEffectNoExecute,
				},
			},
			TerminationGracePeriodSeconds: &gracePeriod,
		},
	}
	tolerationSeconds := []int64{200, 300, 0}
	tests := []struct {
		name                string
		nodeTaints          []v1.Taint
		nodeConditions      []v1.NodeCondition
		pod                 *v1.Pod
		waitForPodCondition string
	}{
		{
			name:                "Taint based evictions for NodeNotReady and 200 tolerationseconds",
			nodeTaints:          []v1.Taint{{Key: v1.TaintNodeNotReady, Effect: v1.TaintEffectNoExecute}},
			nodeConditions:      []v1.NodeCondition{{Type: v1.NodeReady, Status: v1.ConditionFalse}},
			pod:                 testPod,
			waitForPodCondition: "updated with tolerationSeconds of 200",
		},
		{
			name:           "Taint based evictions for NodeNotReady with no pod tolerations",
			nodeTaints:     []v1.Taint{{Key: v1.TaintNodeNotReady, Effect: v1.TaintEffectNoExecute}},
			nodeConditions: []v1.NodeCondition{{Type: v1.NodeReady, Status: v1.ConditionFalse}},
			pod: &v1.Pod{
				ObjectMeta: metav1.ObjectMeta{Name: "testpod1"},
				Spec: v1.PodSpec{
					Containers: []v1.Container{
						{Name: "container", Image: imageutils.GetPauseImageName()},
					},
				},
			},
			waitForPodCondition: "updated with tolerationSeconds=300",
		},
		{
			name:                "Taint based evictions for NodeNotReady and 0 tolerationseconds",
			nodeTaints:          []v1.Taint{{Key: v1.TaintNodeNotReady, Effect: v1.TaintEffectNoExecute}},
			nodeConditions:      []v1.NodeCondition{{Type: v1.NodeReady, Status: v1.ConditionFalse}},
			pod:                 testPod,
			waitForPodCondition: "terminating",
		},
		{
			name:           "Taint based evictions for NodeUnreachable",
			nodeTaints:     []v1.Taint{{Key: v1.TaintNodeUnreachable, Effect: v1.TaintEffectNoExecute}},
			nodeConditions: []v1.NodeCondition{{Type: v1.NodeReady, Status: v1.ConditionUnknown}},
		},
	}

	// Enable TaintBasedEvictions
	defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.TaintBasedEvictions, true)()

	// Build admission chain handler.
	podTolerations := podtolerationrestriction.NewPodTolerationsPlugin(&pluginapi.Configuration{})
	admission := admission.NewChainHandler(
		podTolerations,
		defaulttolerationseconds.NewDefaultTolerationSeconds(),
	)
	for i, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			testCtx := initTestMaster(t, "taint-based-evictions", admission)

			// Build clientset and informers for controllers.
			externalClientset := kubernetes.NewForConfigOrDie(&restclient.Config{
				QPS:           -1,
				Host:          testCtx.httpServer.URL,
				ContentConfig: restclient.ContentConfig{GroupVersion: &schema.GroupVersion{Group: "", Version: "v1"}}})
			externalInformers := informers.NewSharedInformerFactory(externalClientset, time.Second)
			podTolerations.SetExternalKubeClientSet(externalClientset)
			podTolerations.SetExternalKubeInformerFactory(externalInformers)

			testCtx = initTestScheduler(t, testCtx, true, nil)
			defer cleanupTest(t, testCtx)
			cs := testCtx.clientSet
			informers := testCtx.informerFactory
			_, err := cs.CoreV1().Namespaces().Create(context.TODO(), testCtx.ns, metav1.CreateOptions{})
			if err != nil {
				t.Errorf("Failed to create namespace %+v", err)
			}

			// Start NodeLifecycleController for taint.
			nc, err := nodelifecycle.NewNodeLifecycleController(
				informers.Coordination().V1().Leases(),
				informers.Core().V1().Pods(),
				informers.Core().V1().Nodes(),
				informers.Apps().V1().DaemonSets(),
				cs,
				5*time.Second,    // Node monitor grace period
				time.Minute,      // Node startup grace period
				time.Millisecond, // Node monitor period
				time.Second,      // Pod eviction timeout
				100,              // Eviction limiter QPS
				100,              // Secondary eviction limiter QPS
				50,               // Large cluster threshold
				0.55,             // Unhealthy zone threshold
				true,             // Run taint manager
				true,             // Use taint based evictions
			)
			if err != nil {
				t.Errorf("Failed to create node controller: %v", err)
				return
			}

			go nc.Run(testCtx.ctx.Done())

			// Waiting for all controller sync.
			externalInformers.Start(testCtx.ctx.Done())
			externalInformers.WaitForCacheSync(testCtx.ctx.Done())
			informers.Start(testCtx.ctx.Done())
			informers.WaitForCacheSync(testCtx.ctx.Done())

			nodeRes := v1.ResourceList{
				v1.ResourceCPU:    resource.MustParse("4000m"),
				v1.ResourceMemory: resource.MustParse("16Gi"),
				v1.ResourcePods:   resource.MustParse("110"),
			}

			var nodes []*v1.Node
			for i := 0; i < nodeCount; i++ {
				nodes = append(nodes, &v1.Node{
					ObjectMeta: metav1.ObjectMeta{
						Name:   fmt.Sprintf("node-%d", i),
						Labels: map[string]string{v1.LabelZoneRegion: "region1", v1.LabelZoneFailureDomain: "zone1"},
					},
					Spec: v1.NodeSpec{},
					Status: v1.NodeStatus{
						Capacity:    nodeRes,
						Allocatable: nodeRes,
						Conditions: []v1.NodeCondition{
							{
								Type:              v1.NodeReady,
								Status:            v1.ConditionTrue,
								LastHeartbeatTime: metav1.Now(),
							},
						},
					},
				})
				if _, err := cs.CoreV1().Nodes().Create(context.TODO(), nodes[i], metav1.CreateOptions{}); err != nil {
					t.Errorf("Failed to create node, err: %v", err)
				}
			}

			neededNode := nodes[1]
			if test.pod != nil {
				test.pod.Name = fmt.Sprintf("testpod-%d", i)
				if len(test.pod.Spec.Tolerations) > 0 {
					test.pod.Spec.Tolerations[0].TolerationSeconds = &tolerationSeconds[i]
				}

				test.pod, err = cs.CoreV1().Pods(testCtx.ns.Name).Create(context.TODO(), test.pod, metav1.CreateOptions{})
				if err != nil {
					t.Fatalf("Test Failed: error: %v, while creating pod", err)
				}

				if err := waitForPodToSchedule(cs, test.pod); err != nil {
					t.Errorf("Failed to schedule pod %s/%s on the node, err: %v",
						test.pod.Namespace, test.pod.Name, err)
				}
				test.pod, err = cs.CoreV1().Pods(testCtx.ns.Name).Get(context.TODO(), test.pod.Name, metav1.GetOptions{})
				if err != nil {
					t.Fatalf("Test Failed: error: %v, while creating pod", err)
				}
				neededNode, err = cs.CoreV1().Nodes().Get(context.TODO(), test.pod.Spec.NodeName, metav1.GetOptions{})
				if err != nil {
					t.Fatalf("Error while getting node associated with pod %v with err %v", test.pod.Name, err)
				}
			}

			// Regularly send heartbeat event to APIServer so that the cluster doesn't enter fullyDisruption mode.
			// TODO(Huang-Wei): use "NodeDisruptionExclusion" feature to simply the below logic when it's beta.
			for i := 0; i < nodeCount; i++ {
				var conditions []v1.NodeCondition
				// If current node is not <neededNode>
				if neededNode.Name != nodes[i].Name {
					conditions = []v1.NodeCondition{
						{
							Type:   v1.NodeReady,
							Status: v1.ConditionTrue,
						},
					}
				} else {
					c, err := nodeReadyStatus(test.nodeConditions)
					if err != nil {
						t.Error(err)
					}
					// Need to distinguish NodeReady/False and NodeReady/Unknown.
					// If we try to update the node with condition NotReady/False, i.e. expect a NotReady:NoExecute taint
					// we need to keep sending the update event to keep it alive, rather than just sending once.
					if c == v1.ConditionFalse {
						conditions = test.nodeConditions
					} else if c == v1.ConditionUnknown {
						// If it's expected to update the node with condition NotReady/Unknown,
						// i.e. expect a Unreachable:NoExecute taint,
						// we need to only send the update event once to simulate the network unreachable scenario.
						nodeCopy := nodeCopyWithConditions(nodes[i], test.nodeConditions)
						if err := updateNodeStatus(cs, nodeCopy); err != nil && !apierrors.IsNotFound(err) {
							t.Errorf("Cannot update node: %v", err)
						}
						continue
					}
				}
				// Keeping sending NodeReady/True or NodeReady/False events.
				go func(i int) {
					for {
						select {
						case <-testCtx.ctx.Done():
							return
						case <-time.Tick(heartbeatInternal):
							nodeCopy := nodeCopyWithConditions(nodes[i], conditions)
							if err := updateNodeStatus(cs, nodeCopy); err != nil && !apierrors.IsNotFound(err) {
								t.Errorf("Cannot update node: %v", err)
							}
						}
					}
				}(i)
			}

			if err := waitForNodeTaints(cs, neededNode, test.nodeTaints); err != nil {
				t.Errorf("Failed to taint node in test %d <%s>, err: %v", i, neededNode.Name, err)
			}

			if test.pod != nil {
				err = pod.WaitForPodCondition(cs, testCtx.ns.Name, test.pod.Name, test.waitForPodCondition, time.Second*15, func(pod *v1.Pod) (bool, error) {
					// as node is unreachable, pod0 is expected to be in Terminating status
					// rather than getting deleted
					if tolerationSeconds[i] == 0 {
						return pod.DeletionTimestamp != nil, nil
					}
					if seconds, err := getTolerationSeconds(pod.Spec.Tolerations); err == nil {
						return seconds == tolerationSeconds[i], nil
					}
					return false, nil
				})
				if err != nil {
					pod, _ := cs.CoreV1().Pods(testCtx.ns.Name).Get(context.TODO(), test.pod.Name, metav1.GetOptions{})
					t.Fatalf("Error: %v, Expected test pod to be %s but it's %v", err, test.waitForPodCondition, pod)
				}
				cleanupPods(cs, t, []*v1.Pod{test.pod})
			}
			cleanupNodes(cs, t)
			waitForSchedulerCacheCleanup(testCtx.scheduler, t)
		})
	}
}

func getTolerationSeconds(tolerations []v1.Toleration) (int64, error) {
	for _, t := range tolerations {
		if t.Key == v1.TaintNodeNotReady && t.Effect == v1.TaintEffectNoExecute && t.Operator == v1.TolerationOpExists {
			return *t.TolerationSeconds, nil
		}
	}
	return 0, fmt.Errorf("cannot find toleration")
}

// nodeReadyStatus returns the status of first condition with type NodeReady.
// If none of the condition is of type NodeReady, returns an error.
func nodeReadyStatus(conditions []v1.NodeCondition) (v1.ConditionStatus, error) {
	for _, c := range conditions {
		if c.Type != v1.NodeReady {
			continue
		}
		// Just return the first condition with type NodeReady
		return c.Status, nil
	}
	return v1.ConditionFalse, errors.New("None of the conditions is of type NodeReady")
}

func nodeCopyWithConditions(node *v1.Node, conditions []v1.NodeCondition) *v1.Node {
	copy := node.DeepCopy()
	copy.ResourceVersion = "0"
	copy.Status.Conditions = conditions
	for i := range copy.Status.Conditions {
		copy.Status.Conditions[i].LastHeartbeatTime = metav1.Now()
	}
	return copy
}