Merge pull request #57136 from k82cn/k8s_54313

Automatic merge from submit-queue (batch tested with PRs 57136, 59920). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Updated PID pressure node condition.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
part of #54313 

**Release note**:

```release-note
Updated PID pressure node condition
```

pkg/kubelet/apis/stats/v1alpha1/types.go

@@ -56,6 +56,19 @@ type NodeStats struct {
 	// Stats about the underlying container runtime.
 	// +optional
 	Runtime *RuntimeStats `json:"runtime,omitempty"`
+	// Stats about the rlimit of system.
+	// +optional
+	Rlimit *RlimitStats `json:"rlimit,omitempty"`
+}
+
+// RlimitStats are stats rlimit of OS.
+type RlimitStats struct {
+	Time metav1.Time `json:"time"`
+
+	// The max PID of OS.
+	MaxPID *int64 `json:"maxpid,omitempty"`
+	// The number of running process in the OS.
+	NumOfRunningProcesses *int64 `json:"curproc,omitempty"`
 }
 
 // RuntimeStats are stats pertaining to the underlying container runtime.

pkg/kubelet/eviction/api/types.go

@@ -40,6 +40,8 @@ const (
 	SignalAllocatableMemoryAvailable Signal = "allocatableMemory.available"
 	// SignalAllocatableNodeFsAvailable is amount of local storage available for pod allocation
 	SignalAllocatableNodeFsAvailable Signal = "allocatableNodeFs.available"
+	// SignalPIDAvailable is amount of PID available for pod allocation
+	SignalPIDAvailable Signal = "pid.available"
 )
 
 // ThresholdOperator is the operator used to express a Threshold.

pkg/kubelet/eviction/eviction_manager.go

@@ -101,7 +101,8 @@ func NewManager(
 	containerGC ContainerGC,
 	recorder record.EventRecorder,
 	nodeRef *v1.ObjectReference,
-	clock clock.Clock) (Manager, lifecycle.PodAdmitHandler) {
+	clock clock.Clock,
+) (Manager, lifecycle.PodAdmitHandler) {
 	manager := &managerImpl{
 		clock:           clock,
 		killPodFunc:     killPodFunc,
@@ -176,6 +177,13 @@ func (m *managerImpl) IsUnderDiskPressure() bool {
 	return hasNodeCondition(m.nodeConditions, v1.NodeDiskPressure)
 }
 
+// IsUnderPIDPressure returns true if the node is under PID pressure.
+func (m *managerImpl) IsUnderPIDPressure() bool {
+	m.RLock()
+	defer m.RUnlock()
+	return hasNodeCondition(m.nodeConditions, v1.NodePIDPressure)
+}
+
 func startMemoryThresholdNotifier(thresholds []evictionapi.Threshold, observations signalObservations, hard bool, handler thresholdNotifierHandlerFunc) error {
 	for _, threshold := range thresholds {
 		if threshold.Signal != evictionapi.SignalMemoryAvailable || hard != isHardEvictionThreshold(threshold) {

pkg/kubelet/eviction/helpers.go

@@ -72,6 +72,7 @@ func init() {
 	signalToNodeCondition[evictionapi.SignalNodeFsAvailable] = v1.NodeDiskPressure
 	signalToNodeCondition[evictionapi.SignalImageFsInodesFree] = v1.NodeDiskPressure
 	signalToNodeCondition[evictionapi.SignalNodeFsInodesFree] = v1.NodeDiskPressure
+	signalToNodeCondition[evictionapi.SignalPIDAvailable] = v1.NodePIDPressure
 
 	// map signals to resources (and vice-versa)
 	signalToResource = map[evictionapi.Signal]v1.ResourceName{}
@@ -771,6 +772,17 @@ func makeSignalObservations(summary *statsapi.Summary, capacityProvider Capacity
 		}
 	}
 
+	if rlimit := summary.Node.Rlimit; rlimit != nil {
+		if rlimit.NumOfRunningProcesses != nil && rlimit.MaxPID != nil {
+			available := int64(*rlimit.MaxPID) - int64(*rlimit.NumOfRunningProcesses)
+			result[evictionapi.SignalPIDAvailable] = signalObservation{
+				available: resource.NewQuantity(available, resource.BinarySI),
+				capacity:  resource.NewQuantity(int64(*rlimit.MaxPID), resource.BinarySI),
+				time:      rlimit.Time,
+			}
+		}
+	}
+
 	if memoryAllocatableCapacity, ok := capacityProvider.GetCapacity()[v1.ResourceMemory]; ok {
 		memoryAllocatableAvailable := memoryAllocatableCapacity.Copy()
 		if reserved, exists := capacityProvider.GetNodeAllocatableReservation()[v1.ResourceMemory]; exists {

pkg/kubelet/eviction/types.go

@@ -60,6 +60,9 @@ type Manager interface {
 
 	// IsUnderDiskPressure returns true if the node is under disk pressure.
 	IsUnderDiskPressure() bool
+
+	// IsUnderPIDPressure returns true if the node is under PID pressure.
+	IsUnderPIDPressure() bool
 }
 
 // DiskInfoProvider is responsible for informing the manager how disk is configured.

pkg/kubelet/kubelet_node_status.go

@@ -853,6 +853,62 @@ func (kl *Kubelet) setNodeMemoryPressureCondition(node *v1.Node) {
 	}
 }
 
+// setNodePIDPressureCondition for the node.
+// TODO: this needs to move somewhere centralized...
+func (kl *Kubelet) setNodePIDPressureCondition(node *v1.Node) {
+	currentTime := metav1.NewTime(kl.clock.Now())
+	var condition *v1.NodeCondition
+
+	// Check if NodePIDPressure condition already exists and if it does, just pick it up for update.
+	for i := range node.Status.Conditions {
+		if node.Status.Conditions[i].Type == v1.NodePIDPressure {
+			condition = &node.Status.Conditions[i]
+		}
+	}
+
+	newCondition := false
+	// If the NodePIDPressure condition doesn't exist, create one
+	if condition == nil {
+		condition = &v1.NodeCondition{
+			Type:   v1.NodePIDPressure,
+			Status: v1.ConditionUnknown,
+		}
+		// cannot be appended to node.Status.Conditions here because it gets
+		// copied to the slice. So if we append to the slice here none of the
+		// updates we make below are reflected in the slice.
+		newCondition = true
+	}
+
+	// Update the heartbeat time
+	condition.LastHeartbeatTime = currentTime
+
+	// Note: The conditions below take care of the case when a new NodePIDPressure condition is
+	// created and as well as the case when the condition already exists. When a new condition
+	// is created its status is set to v1.ConditionUnknown which matches either
+	// condition.Status != v1.ConditionTrue or
+	// condition.Status != v1.ConditionFalse in the conditions below depending on whether
+	// the kubelet is under PID pressure or not.
+	if kl.evictionManager.IsUnderPIDPressure() {
+		if condition.Status != v1.ConditionTrue {
+			condition.Status = v1.ConditionTrue
+			condition.Reason = "KubeletHasInsufficientPID"
+			condition.Message = "kubelet has insufficient PID available"
+			condition.LastTransitionTime = currentTime
+			kl.recordNodeStatusEvent(v1.EventTypeNormal, "NodeHasInsufficientPID")
+		}
+	} else if condition.Status != v1.ConditionFalse {
+		condition.Status = v1.ConditionFalse
+		condition.Reason = "KubeletHasSufficientPID"
+		condition.Message = "kubelet has sufficient PID available"
+		condition.LastTransitionTime = currentTime
+		kl.recordNodeStatusEvent(v1.EventTypeNormal, "NodeHasSufficientPID")
+	}
+
+	if newCondition {
+		node.Status.Conditions = append(node.Status.Conditions, *condition)
+	}
+}
+
 // setNodeDiskPressureCondition for the node.
 // TODO: this needs to move somewhere centralized...
 func (kl *Kubelet) setNodeDiskPressureCondition(node *v1.Node) {
@@ -995,6 +1051,7 @@ func (kl *Kubelet) defaultNodeStatusFuncs() []func(*v1.Node) error {
 		withoutError(kl.setNodeOODCondition),
 		withoutError(kl.setNodeMemoryPressureCondition),
 		withoutError(kl.setNodeDiskPressureCondition),
+		withoutError(kl.setNodePIDPressureCondition),
 		withoutError(kl.setNodeReadyCondition),
 		withoutError(kl.setNodeVolumesInUseStatus),
 		withoutError(kl.recordNodeSchedulableEvent),

pkg/kubelet/kubelet_node_status_test.go

@@ -279,6 +279,14 @@ func TestUpdateNewNodeStatus(t *testing.T) {
 					LastHeartbeatTime:  metav1.Time{},
 					LastTransitionTime: metav1.Time{},
 				},
+				{
+					Type:               v1.NodePIDPressure,
+					Status:             v1.ConditionFalse,
+					Reason:             "KubeletHasSufficientPID",
+					Message:            fmt.Sprintf("kubelet has sufficient PID available"),
+					LastHeartbeatTime:  metav1.Time{},
+					LastTransitionTime: metav1.Time{},
+				},
 				{
 					Type:               v1.NodeReady,
 					Status:             v1.ConditionTrue,
@@ -335,7 +343,8 @@ func TestUpdateNewNodeStatus(t *testing.T) {
 	}
 
 	// Version skew workaround. See: https://github.com/kubernetes/kubernetes/issues/16961
-	assert.Equal(t, v1.NodeReady, updatedNode.Status.Conditions[len(updatedNode.Status.Conditions)-1].Type, "NotReady should be last")
+	assert.Equal(t, v1.NodeReady, updatedNode.Status.Conditions[len(updatedNode.Status.Conditions)-1].Type,
+		"NotReady should be last")
 	assert.Len(t, updatedNode.Status.Images, maxImagesInNodeStatus)
 	assert.True(t, apiequality.Semantic.DeepEqual(expectedNode, updatedNode), "%s", diff.ObjectDiff(expectedNode, updatedNode))
 }
@@ -387,6 +396,14 @@ func TestUpdateExistingNodeStatus(t *testing.T) {
 					LastHeartbeatTime:  metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
 					LastTransitionTime: metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
 				},
+				{
+					Type:               v1.NodePIDPressure,
+					Status:             v1.ConditionFalse,
+					Reason:             "KubeletHasSufficientPID",
+					Message:            fmt.Sprintf("kubelet has sufficient PID available"),
+					LastHeartbeatTime:  metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
+					LastTransitionTime: metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
+				},
 				{
 					Type:               v1.NodeReady,
 					Status:             v1.ConditionTrue,
@@ -454,6 +471,14 @@ func TestUpdateExistingNodeStatus(t *testing.T) {
 					LastHeartbeatTime:  metav1.Time{},
 					LastTransitionTime: metav1.Time{},
 				},
+				{
+					Type:               v1.NodePIDPressure,
+					Status:             v1.ConditionFalse,
+					Reason:             "KubeletHasSufficientPID",
+					Message:            fmt.Sprintf("kubelet has sufficient PID available"),
+					LastHeartbeatTime:  metav1.Time{},
+					LastTransitionTime: metav1.Time{},
+				},
 				{
 					Type:               v1.NodeReady,
 					Status:             v1.ConditionTrue,
@@ -650,6 +675,14 @@ func TestUpdateNodeStatusWithRuntimeStateError(t *testing.T) {
 					LastHeartbeatTime:  metav1.Time{},
 					LastTransitionTime: metav1.Time{},
 				},
+				{
+					Type:               v1.NodePIDPressure,
+					Status:             v1.ConditionFalse,
+					Reason:             "KubeletHasSufficientPID",
+					Message:            fmt.Sprintf("kubelet has sufficient PID available"),
+					LastHeartbeatTime:  metav1.Time{},
+					LastTransitionTime: metav1.Time{},
+				},
 				{}, //placeholder
 			},
 			NodeInfo: v1.NodeSystemInfo{

pkg/kubelet/server/server_test.go

@@ -176,6 +176,7 @@ func (fk *fakeKubelet) ListVolumesForPod(podUID types.UID) (map[string]volume.Vo
 func (_ *fakeKubelet) RootFsStats() (*statsapi.FsStats, error)     { return nil, nil }
 func (_ *fakeKubelet) ListPodStats() ([]statsapi.PodStats, error)  { return nil, nil }
 func (_ *fakeKubelet) ImageFsStats() (*statsapi.FsStats, error)    { return nil, nil }
+func (_ *fakeKubelet) RlimitStats() (*statsapi.RlimitStats, error) { return nil, nil }
 func (_ *fakeKubelet) GetCgroupStats(cgroupName string, updateStats bool) (*statsapi.ContainerStats, *statsapi.NetworkStats, error) {
 	return nil, nil, nil
 }

pkg/kubelet/server/stats/handler.go

@@ -78,6 +78,9 @@ type StatsProvider interface {
 	ListVolumesForPod(podUID types.UID) (map[string]volume.Volume, bool)
 	// GetPods returns the specs of all the pods running on this node.
 	GetPods() []*v1.Pod
+
+	// RlimitStats returns the rlimit stats of system.
+	RlimitStats() (*statsapi.RlimitStats, error)
 }
 
 type handler struct {

pkg/kubelet/server/stats/summary.go

@@ -67,6 +67,10 @@ func (sp *summaryProviderImpl) Get(updateStats bool) (*statsapi.Summary, error)
 	if err != nil {
 		return nil, fmt.Errorf("failed to list pod stats: %v", err)
 	}
+	rlimit, err := sp.provider.RlimitStats()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get rlimit stats: %v", err)
+	}
 
 	nodeStats := statsapi.NodeStats{
 		NodeName:  node.Name,
@@ -76,6 +80,7 @@ func (sp *summaryProviderImpl) Get(updateStats bool) (*statsapi.Summary, error)
 		StartTime: rootStats.StartTime,
 		Fs:        rootFsStats,
 		Runtime:   &statsapi.RuntimeStats{ImageFs: imageFsStats},
+		Rlimit:    rlimit,
 	}
 
 	systemContainers := map[string]string{

pkg/kubelet/server/stats/summary_test.go

@@ -58,6 +58,7 @@ func TestSummaryProvider(t *testing.T) {
 			"/misc":    {cs: getContainerStats(), ns: getNetworkStats()},
 			"/kubelet": {cs: getContainerStats(), ns: getNetworkStats()},
 		}
+		rlimitStats = getRlimitStats()
 	)
 
 	assert := assert.New(t)
@@ -69,6 +70,7 @@ func TestSummaryProvider(t *testing.T) {
 		On("ListPodStats").Return(podStats, nil).
 		On("ImageFsStats").Return(imageFsStats, nil).
 		On("RootFsStats").Return(rootFsStats, nil).
+		On("RlimitStats").Return(rlimitStats, nil).
 		On("GetCgroupStats", "/", true).Return(cgroupStatsMap["/"].cs, cgroupStatsMap["/"].ns, nil).
 		On("GetCgroupStats", "/runtime", false).Return(cgroupStatsMap["/runtime"].cs, cgroupStatsMap["/runtime"].ns, nil).
 		On("GetCgroupStats", "/misc", false).Return(cgroupStatsMap["/misc"].cs, cgroupStatsMap["/misc"].ns, nil).
@@ -141,3 +143,10 @@ func getNetworkStats() *statsapi.NetworkStats {
 	f.Fuzz(v)
 	return v
 }
+
+func getRlimitStats() *statsapi.RlimitStats {
+	f := fuzz.New().NilChance(0)
+	v := &statsapi.RlimitStats{}
+	f.Fuzz(v)
+	return v
+}

pkg/kubelet/server/stats/testing/mock_stats_provider.go

@@ -278,3 +278,26 @@ func (_m *StatsProvider) RootFsStats() (*v1alpha1.FsStats, error) {
 
 	return r0, r1
 }
+
+// RlimitStats provides a mock function with given fields:
+func (_m *StatsProvider) RlimitStats() (*v1alpha1.RlimitStats, error) {
+	ret := _m.Called()
+
+	var r0 *v1alpha1.RlimitStats
+	if rf, ok := ret.Get(0).(func() *v1alpha1.RlimitStats); ok {
+		r0 = rf()
+	} else {
+		if ret.Get(0) != nil {
+			r0 = ret.Get(0).(*v1alpha1.RlimitStats)
+		}
+	}
+
+	var r1 error
+	if rf, ok := ret.Get(1).(func() error); ok {
+		r1 = rf()
+	} else {
+		r1 = ret.Error(1)
+	}
+
+	return r0, r1
+}

pkg/kubelet/stats/BUILD

@@ -7,7 +7,42 @@ go_library(
         "cri_stats_provider.go",
         "helper.go",
         "stats_provider.go",
+    ] + select({
+        "@io_bazel_rules_go//go/platform:android": [
+            "stats_provider_unsupported.go",
         ],
+        "@io_bazel_rules_go//go/platform:darwin": [
+            "stats_provider_unsupported.go",
+        ],
+        "@io_bazel_rules_go//go/platform:dragonfly": [
+            "stats_provider_unsupported.go",
+        ],
+        "@io_bazel_rules_go//go/platform:freebsd": [
+            "stats_provider_unsupported.go",
+        ],
+        "@io_bazel_rules_go//go/platform:linux": [
+            "stats_provider_linux.go",
+        ],
+        "@io_bazel_rules_go//go/platform:nacl": [
+            "stats_provider_unsupported.go",
+        ],
+        "@io_bazel_rules_go//go/platform:netbsd": [
+            "stats_provider_unsupported.go",
+        ],
+        "@io_bazel_rules_go//go/platform:openbsd": [
+            "stats_provider_unsupported.go",
+        ],
+        "@io_bazel_rules_go//go/platform:plan9": [
+            "stats_provider_unsupported.go",
+        ],
+        "@io_bazel_rules_go//go/platform:solaris": [
+            "stats_provider_unsupported.go",
+        ],
+        "@io_bazel_rules_go//go/platform:windows": [
+            "stats_provider_unsupported.go",
+        ],
+        "//conditions:default": [],
+    }),
     importpath = "k8s.io/kubernetes/pkg/kubelet/stats",
     visibility = ["//visibility:public"],
     deps = [

pkg/kubelet/stats/stats_provider.go

@@ -77,6 +77,7 @@ type StatsProvider struct {
 	podManager   kubepod.Manager
 	runtimeCache kubecontainer.RuntimeCache
 	containerStatsProvider
+	rlimitStatsProvider
 }
 
 // containerStatsProvider is an interface that provides the stats of the
@@ -87,6 +88,10 @@ type containerStatsProvider interface {
 	ImageFsDevice() (string, error)
 }
 
+type rlimitStatsProvider interface {
+	RlimitStats() (*statsapi.RlimitStats, error)
+}
+
 // GetCgroupStats returns the stats of the cgroup with the cgroupName. Note that
 // this function doesn't generate filesystem stats.
 func (p *StatsProvider) GetCgroupStats(cgroupName string, updateStats bool) (*statsapi.ContainerStats, *statsapi.NetworkStats, error) {

pkg/kubelet/stats/stats_provider_linux.go

@@ -0,0 +1,48 @@
+// +build linux
+
+/*
+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 stats
+
+import (
+	"io/ioutil"
+	"strconv"
+	"syscall"
+	"time"
+
+	"k8s.io/apimachinery/pkg/apis/meta/v1"
+	statsapi "k8s.io/kubernetes/pkg/kubelet/apis/stats/v1alpha1"
+)
+
+func (p *StatsProvider) RlimitStats() (*statsapi.RlimitStats, error) {
+	rlimit := &statsapi.RlimitStats{}
+
+	if content, err := ioutil.ReadFile("/proc/sys/kernel/pid_max"); err == nil {
+		if maxPid, err := strconv.ParseInt(string(content[:len(content)-1]), 10, 64); err == nil {
+			rlimit.MaxPID = &maxPid
+		}
+	}
+
+	var info syscall.Sysinfo_t
+	syscall.Sysinfo(&info)
+	procs := int64(info.Procs)
+	rlimit.NumOfRunningProcesses = &procs
+
+	rlimit.Time = v1.NewTime(time.Now())
+
+	return rlimit, nil
+}

pkg/kubelet/stats/stats_provider_unsupported.go

@@ -0,0 +1,27 @@
+// +build !linux
+
+/*
+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 stats
+
+import (
+	statsapi "k8s.io/kubernetes/pkg/kubelet/apis/stats/v1alpha1"
+)
+
+func (p *StatsProvider) RlimitStats() (*statsapi.RlimitStats, error) {
+	return nil, nil
+}

staging/src/k8s.io/api/core/v1/types.go

@@ -3962,6 +3962,8 @@ const (
 	NodeMemoryPressure NodeConditionType = "MemoryPressure"
 	// NodeDiskPressure means the kubelet is under pressure due to insufficient available disk.
 	NodeDiskPressure NodeConditionType = "DiskPressure"
+	// NodePIDPressure means the kubelet is under pressure due to insufficient available PID.
+	NodePIDPressure NodeConditionType = "PIDPressure"
 	// NodeNetworkUnavailable means that network for the node is not correctly configured.
 	NodeNetworkUnavailable NodeConditionType = "NetworkUnavailable"
 	// NodeKubeletConfigOk indicates whether the kubelet is correctly configured

test/e2e_node/summary_test.go

@@ -277,6 +277,11 @@ var _ = framework.KubeDescribe("Summary API", func() {
 							"InodesUsed": bounded(0, 1E8),
 						}),
 					}),
+					"Rlimit": ptrMatchAllFields(gstruct.Fields{
+						"Time":                  recent(maxStatsAge),
+						"MaxPID":                bounded(0, 1E8),
+						"NumOfRunningProcesses": bounded(0, 1E8),
+					}),
 				}),
 				// Ignore extra pods since the tests run in parallel.
 				"Pods": gstruct.MatchElements(summaryObjectID, gstruct.IgnoreExtras, gstruct.Elements{