eviction_manager: add unit test for PID pressure

(cherry picked from commit 696d0156565ebca494d5a67f0582bf3a2a2e8079)

pkg/kubelet/eviction/eviction_manager_test.go

@@ -115,6 +115,14 @@ func makePodWithMemoryStats(name string, priority int32, requests v1.ResourceLis
 	return pod, podStats
 }
 
+func makePodWithPIDStats(name string, priority int32, processCount uint64) (*v1.Pod, statsapi.PodStats) {
+	pod := newPod(name, priority, []v1.Container{
+		newContainer(name, nil, nil),
+	}, nil)
+	podStats := newPodProcessStats(pod, processCount)
+	return pod, podStats
+}
+
 func makePodWithDiskStats(name string, priority int32, requests v1.ResourceList, limits v1.ResourceList, rootFsUsed, logsUsed, perLocalVolumeUsed string) (*v1.Pod, statsapi.PodStats) {
 	pod := newPod(name, priority, []v1.Container{
 		newContainer(name, requests, limits),
@@ -149,6 +157,32 @@ func makePodWithLocalStorageCapacityIsolationOpen(name string, priority int32, r
 	return pod, podStats
 }
 
+func makePIDStats(nodeAvailablePIDs string, numberOfRunningProcesses string, podStats map[*v1.Pod]statsapi.PodStats) *statsapi.Summary {
+	val := resource.MustParse(nodeAvailablePIDs)
+	availablePIDs := int64(val.Value())
+
+	parsed := resource.MustParse(numberOfRunningProcesses)
+	NumberOfRunningProcesses := int64(parsed.Value())
+	result := &statsapi.Summary{
+		Node: statsapi.NodeStats{
+			Rlimit: &statsapi.RlimitStats{
+				MaxPID:                &availablePIDs,
+				NumOfRunningProcesses: &NumberOfRunningProcesses,
+			},
+			SystemContainers: []statsapi.ContainerStats{
+				{
+					Name: statsapi.SystemContainerPods,
+				},
+			},
+		},
+		Pods: []statsapi.PodStats{},
+	}
+	for _, podStat := range podStats {
+		result.Pods = append(result.Pods, podStat)
+	}
+	return result
+}
+
 func makeMemoryStats(nodeAvailableBytes string, podStats map[*v1.Pod]statsapi.PodStats) *statsapi.Summary {
 	val := resource.MustParse(nodeAvailableBytes)
 	availableBytes := uint64(val.Value())
@@ -347,6 +381,105 @@ func TestMemoryPressure_VerifyPodStatus(t *testing.T) {
 	}
 }
 
+func TestPIDPressure_VerifyPodStatus(t *testing.T) {
+	testCases := map[string]struct {
+		wantPodStatus v1.PodStatus
+	}{
+		"eviction due to pid pressure": {
+			wantPodStatus: v1.PodStatus{
+				Phase:   v1.PodFailed,
+				Reason:  "Evicted",
+				Message: "The node was low on resource: pids. Threshold quantity: 1200, available: 500. ",
+			},
+		},
+	}
+	for name, tc := range testCases {
+		for _, enablePodDisruptionConditions := range []bool{true, false} {
+			t.Run(fmt.Sprintf("%s;PodDisruptionConditions=%v", name, enablePodDisruptionConditions), func(t *testing.T) {
+				defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.PodDisruptionConditions, enablePodDisruptionConditions)()
+
+				podMaker := makePodWithPIDStats
+				summaryStatsMaker := makePIDStats
+				podsToMake := []podToMake{
+					{name: "below-requests"},
+					{name: "above-requests"},
+				}
+				pods := []*v1.Pod{}
+				podStats := map[*v1.Pod]statsapi.PodStats{}
+				for _, podToMake := range podsToMake {
+					pod, podStat := podMaker(podToMake.name, podToMake.priority, 2)
+					pods = append(pods, pod)
+					podStats[pod] = podStat
+				}
+				activePodsFunc := func() []*v1.Pod {
+					return pods
+				}
+
+				fakeClock := testingclock.NewFakeClock(time.Now())
+				podKiller := &mockPodKiller{}
+				diskInfoProvider := &mockDiskInfoProvider{dedicatedImageFs: false}
+				diskGC := &mockDiskGC{err: nil}
+				nodeRef := &v1.ObjectReference{Kind: "Node", Name: "test", UID: types.UID("test"), Namespace: ""}
+
+				config := Config{
+					PressureTransitionPeriod: time.Minute * 5,
+					Thresholds: []evictionapi.Threshold{
+						{
+							Signal:   evictionapi.SignalPIDAvailable,
+							Operator: evictionapi.OpLessThan,
+							Value: evictionapi.ThresholdValue{
+								Quantity: quantityMustParse("1200"),
+							},
+						},
+					},
+				}
+				summaryProvider := &fakeSummaryProvider{result: summaryStatsMaker("1500", "1000", podStats)}
+				manager := &managerImpl{
+					clock:                        fakeClock,
+					killPodFunc:                  podKiller.killPodNow,
+					imageGC:                      diskGC,
+					containerGC:                  diskGC,
+					config:                       config,
+					recorder:                     &record.FakeRecorder{},
+					summaryProvider:              summaryProvider,
+					nodeRef:                      nodeRef,
+					nodeConditionsLastObservedAt: nodeConditionsObservedAt{},
+					thresholdsFirstObservedAt:    thresholdsObservedAt{},
+				}
+
+				// synchronize to detect the memory pressure
+				manager.synchronize(diskInfoProvider, activePodsFunc)
+
+				// verify pid pressure is detected
+				if !manager.IsUnderPIDPressure() {
+					t.Fatalf("Manager should have detected PID pressure")
+				}
+
+				// verify a pod is selected for eviction
+				if podKiller.pod == nil {
+					t.Fatalf("Manager should have selected a pod for eviction")
+				}
+
+				wantPodStatus := tc.wantPodStatus.DeepCopy()
+				if enablePodDisruptionConditions {
+					wantPodStatus.Conditions = append(wantPodStatus.Conditions, v1.PodCondition{
+						Type:    "DisruptionTarget",
+						Status:  "True",
+						Reason:  "TerminationByKubelet",
+						Message: "The node was low on resource: pids. Threshold quantity: 1200, available: 500. ",
+					})
+				}
+
+				// verify the pod status after applying the status update function
+				podKiller.statusFn(&podKiller.pod.Status)
+				if diff := cmp.Diff(*wantPodStatus, podKiller.pod.Status, cmpopts.IgnoreFields(v1.PodCondition{}, "LastProbeTime", "LastTransitionTime")); diff != "" {
+					t.Errorf("Unexpected pod status of the evicted pod (-want,+got):\n%s", diff)
+				}
+			})
+		}
+	}
+}
+
 func TestDiskPressureNodeFs_VerifyPodStatus(t *testing.T) {
 	testCases := map[string]struct {
 		nodeFsStats                   string