概述

k8s v1.16版本中NodeController已经分为了NodeIpamController与NodeLifecycleController，本文主要介绍NodeLifecycleController。

NodeLifecycleController主要功能有：（1）定期检查node的心跳上报，某个node间隔一定时间都没有心跳上报时，更新node的ready condition值为false或unknown，开启了污点驱逐的情况下，给该node添加NoExecute的污点；（2）当污点驱逐未开启时，当node的ready Condition值为false或unknown且已经持续了一段时间（该时间可配置）时，对该node上的pod做驱逐（删除）操作；（3）当污点驱逐开启时，node上有NoExecute污点后，立马驱逐（删除）不能容忍污点的pod，对于能容忍该污点的pod，则等待所有污点的容忍时间里最小值后，pod才被驱逐（删除）；

源码分析

源码分析分成3部分：（1）启动参数分析；（2）初始化与相关结构体分析；（3）处理逻辑分析；

(资料图)

1.相关启动参数分析

// cmd/kube-controller-manager/app/core.gofunc startNodeLifecycleController(ctx ControllerContext) (http.Handler, bool, error) {lifecycleController, err := lifecyclecontroller.NewNodeLifecycleController(ctx.InformerFactory.Coordination().V1().Leases(),ctx.InformerFactory.Core().V1().Pods(),ctx.InformerFactory.Core().V1().Nodes(),ctx.InformerFactory.Apps().V1().DaemonSets(),// node lifecycle controller uses existing cluster role from node-controllerctx.ClientBuilder.ClientOrDie("node-controller"),ctx.ComponentConfig.KubeCloudShared.NodeMonitorPeriod.Duration,ctx.ComponentConfig.NodeLifecycleController.NodeStartupGracePeriod.Duration,ctx.ComponentConfig.NodeLifecycleController.NodeMonitorGracePeriod.Duration,ctx.ComponentConfig.NodeLifecycleController.PodEvictionTimeout.Duration,ctx.ComponentConfig.NodeLifecycleController.NodeEvictionRate,ctx.ComponentConfig.NodeLifecycleController.SecondaryNodeEvictionRate,ctx.ComponentConfig.NodeLifecycleController.LargeClusterSizeThreshold,ctx.ComponentConfig.NodeLifecycleController.UnhealthyZoneThreshold,ctx.ComponentConfig.NodeLifecycleController.EnableTaintManager,utilfeature.DefaultFeatureGate.Enabled(features.TaintBasedEvictions),)if err != nil {return nil, true, err}go lifecycleController.Run(ctx.Stop)return nil, true, nil}

看到上面的startNodeLifecycleController函数中lifecyclecontroller.NewNodeLifecycleController方法的入参，其中传入了多个kube-controller-manager的启动参数；

（1）ctx.ComponentConfig.KubeCloudShared.NodeMonitorPeriod.Duration；

即kcm启动参数--node-monitor-period，默认值5秒，代表NodeLifecycleController中更新同步node对象的status值（node的污点、node的condition值）的周期；

fs.DurationVar(&o.NodeMonitorPeriod.Duration, "node-monitor-period", o.NodeMonitorPeriod.Duration,"The period for syncing NodeStatus in NodeController.")

（2）ctx.ComponentConfig.NodeLifecycleController.NodeStartupGracePeriod.Duration；

即kcm启动参数--node-startup-grace-period，默认值60秒，代表node启动后多久才会更新node对象的conditions值；

fs.DurationVar(&o.NodeStartupGracePeriod.Duration, "node-startup-grace-period", o.NodeStartupGracePeriod.Duration,"Amount of time which we allow starting Node to be unresponsive before marking it unhealthy.")

（3）ctx.ComponentConfig.NodeLifecycleController.NodeMonitorGracePeriod.Duration；

即kcm启动参数--node-monitor-grace-period，默认值40秒，代表在距离上一次上报心跳时间超过40s后，将该node的conditions值更新为unknown（kubelet通过更新node lease来上报心跳）；

fs.DurationVar(&o.NodeMonitorGracePeriod.Duration, "node-monitor-grace-period", o.NodeMonitorGracePeriod.Duration,"Amount of time which we allow running Node to be unresponsive before marking it unhealthy. "+"Must be N times more than kubelet"s nodeStatusUpdateFrequency, "+"where N means number of retries allowed for kubelet to post node status.")

（4）ctx.ComponentConfig.NodeLifecycleController.PodEvictionTimeout.Duration；

即kcm启动参数--pod-eviction-timeout，默认值5分钟，当不开启污点驱逐时该参数起效，当node的ready condition值变为false或unknown并持续了5分钟后，将驱逐（删除）该node上的pod；

fs.DurationVar(&o.PodEvictionTimeout.Duration, "pod-eviction-timeout", o.PodEvictionTimeout.Duration, "The grace period for deleting pods on failed nodes.")

（5）ctx.ComponentConfig.NodeLifecycleController.EnableTaintManager；

即kcm启动参数--enable-taint-manager，默认值true，代表启动taintManager，当已经调度到该node上的pod不能容忍node的NoExecute污点时，由TaintManager负责驱逐此类pod，若为false即不启动taintManager，则根据--pod-eviction-timeout来做驱逐操作；

fs.BoolVar(&o.EnableTaintManager, "enable-taint-manager", o.EnableTaintManager, "WARNING: Beta feature. If set to true enables NoExecute Taints and will evict all not-tolerating Pod running on Nodes tainted with this kind of Taints.")

（6）utilfeature.DefaultFeatureGate.Enabled(features.TaintBasedEvictions)；

即kcm启动参数--feature-gates=TaintBasedEvictions=xxx，默认值true，配合--enable-taint-manager共同作用，两者均为true，才会开启污点驱逐；

（7）ctx.ComponentConfig.NodeLifecycleController.NodeEvictionRate；

即kcm启动参数--node-eviction-rate，默认值0.1，代表当集群下某个zone（zone的概念后面详细介绍）为healthy时，每秒应该触发pod驱逐操作的node数量，默认0.1，即每10s触发1个node上的pod驱逐操作；

fs.Float32Var(&o.NodeEvictionRate, "node-eviction-rate", 0.1, "Number of nodes per second on which pods are deleted in case of node failure when a zone is healthy (see --unhealthy-zone-threshold for definition of healthy/unhealthy). Zone refers to entire cluster in non-multizone clusters.")

（8）ctx.ComponentConfig.NodeLifecycleController.SecondaryNodeEvictionRate；

即kcm启动参数--secondary-node-eviction-rate，代表如果某个zone下的unhealthy节点的百分比超过--unhealthy-zone-threshold （默认为 0.55）时，驱逐速率将会减小，如果不是LargeCluster（zone节点数量小于等于--large-cluster-size-threshold个，默认为 50），驱逐操作将会停止，如果是LargeCluster，驱逐速率将降为每秒--secondary-node-eviction-rate 个，默认为0.01；

fs.Float32Var(&o.SecondaryNodeEvictionRate, "secondary-node-eviction-rate", 0.01, "Number of nodes per second on which pods are deleted in case of node failure when a zone is unhealthy (see --unhealthy-zone-threshold for definition of healthy/unhealthy). Zone refers to entire cluster in non-multizone clusters. This value is implicitly overridden to 0 if the cluster size is smaller than --large-cluster-size-threshold.")

（9）ctx.ComponentConfig.NodeLifecycleController.LargeClusterSizeThreshold；

即kcm启动参数--large-cluster-size-threshold，默认值50，当某zone的节点数超过该值时，认为该zone是一个LargeCluster，不是LargeCluster时，对应的SecondaryNodeEvictionRate配置会被设置为0；

fs.Int32Var(&o.LargeClusterSizeThreshold, "large-cluster-size-threshold", 50, "Number of nodes from which NodeController treats the cluster as large for the eviction logic purposes. --secondary-node-eviction-rate is implicitly overridden to 0 for clusters this size or smaller.")

（10）ctx.ComponentConfig.NodeLifecycleController.UnhealthyZoneThreshold；

即kcm启动参数--unhealthy-zone-threshold，代表认定某zone为unhealthy的阈值，即会影响什么时候开启二级驱逐速率；默认值0.55，当该zone中not ready节点（ready condition值不为true）数目超过55%，认定该zone为unhealthy；

fs.Float32Var(&o.UnhealthyZoneThreshold, "unhealthy-zone-threshold", 0.55, "Fraction of Nodes in a zone which needs to be not Ready (minimum 3) for zone to be treated as unhealthy. ")

（11）--feature-gates=NodeLease=xxx：默认值true，使用lease对象上报node心跳信息，替换老的更新node的status的方式，能大大减轻apiserver的负担；

zone概念介绍

根据每个node对象的region和zone的label值，将node划分到不同的zone中；

region、zone值都相同的node，划分为同一个zone；

zone状态介绍

zone状态有四种，分别是：（1）Initial：初始化状态；（2）FullDisruption：ready的node数量为0，not ready的node数量大于0；（3）PartialDisruption：not ready的node数量大于2且其占比大于等于unhealthyZoneThreshold；（4）Normal：上述三种状态以外的情形，都属于该状态；

需要注意二级驱逐速率对驱逐的影响，即kcm启动参数--secondary-node-eviction-rate，代表如果某个zone下的unhealthy节点的百分比超过--unhealthy-zone-threshold （默认为 0.55）时，驱逐速率将会减小，如果不是LargeCluster（zone节点数量小于等于--large-cluster-size-threshold，默认为 50），驱逐操作将会停止，如果是LargeCluster，驱逐速率将降为每秒--secondary-node-eviction-rate 个，默认为0.01；

// pkg/controller/nodelifecycle/node_lifecycle_controller.gofunc (nc *Controller) ComputeZoneState(nodeReadyConditions []*v1.NodeCondition) (int, ZoneState) {readyNodes := 0notReadyNodes := 0for i := range nodeReadyConditions {if nodeReadyConditions[i] != nil && nodeReadyConditions[i].Status == v1.ConditionTrue {readyNodes++} else {notReadyNodes++}}switch {case readyNodes == 0 && notReadyNodes > 0:return notReadyNodes, stateFullDisruptioncase notReadyNodes > 2 && float32(notReadyNodes)/float32(notReadyNodes+readyNodes) >= nc.unhealthyZoneThreshold:return notReadyNodes, statePartialDisruptiondefault:return notReadyNodes, stateNormal}}

2.初始化与相关结构体分析2.1 Controller结构体分析

Controller结构体关键属性：（1）taintManager：负责污点驱逐的manager；（2）enterPartialDisruptionFunc：返回当zone状态为PartialDisruption时的驱逐速率（node节点数量超过largeClusterThreshold时，返回secondaryEvictionLimiterQPS，即kcm启动参数--secondary-node-eviction-rate，否则返回0）；（3）enterFullDisruptionFunc：返回当zone状态为FullDisruption时的驱逐速率（直接返回NodeEvictionRate值，kcm启动参数--node-eviction-rate）；（4）computeZoneStateFunc：计算zone状态的方法，即上面zone状态介绍中的ComputeZoneState方法；（5）nodeHealthMap：用于记录所有node的最近一次的状态信息；（6）zoneStates：用于记录所有zone的状态；（7）nodeMonitorPeriod、nodeStartupGracePeriod、nodeMonitorGracePeriod、podEvictionTimeout、evictionLimiterQPS、secondaryEvictionLimiterQPS、largeClusterThreshold、unhealthyZoneThreshold，上面介绍启动参数时已经做了分析；（8）runTaintManager：kcm启动参数--enable-taint-manager赋值，代表是否启动taintManager；（9）useTaintBasedEvictions：代表是否开启污点驱逐，kcm启动参数--feature-gates=TaintBasedEvictions=xxx赋值，默认值true，配合--enable-taint-manager共同作用，两者均为true，才会开启污点驱逐；

Controller结构体中的两个关键队列：（1）zonePodEvictor：pod需要被驱逐的node节点队列（只有在未开启污点驱逐时，才用到该队列），当node的ready condition变为false或unknown且持续了podEvictionTimeout的时间，会将该node放入该队列，然后有worker负责从该队列中读取node，去执行node上的pod驱逐操作；（2）zoneNoExecuteTainter：需要更新taint的node节点队列，当node的ready condition变为false或unknown时，会将该node放入该队列，然后有worker负责从该队列中读取node，去执行taint更新操作（增加notReady或unreachable的taint）；

// pkg/controller/nodelifecycle/node_lifecycle_controller.gotype Controller struct {    ...taintManager *scheduler.NoExecuteTaintManager// This timestamp is to be used instead of LastProbeTime stored in Condition. We do this// to avoid the problem with time skew across the cluster.now func() metav1.TimeenterPartialDisruptionFunc func(nodeNum int) float32enterFullDisruptionFunc    func(nodeNum int) float32computeZoneStateFunc       func(nodeConditions []*v1.NodeCondition) (int, ZoneState)knownNodeSet map[string]*v1.Node// per Node map storing last observed health together with a local time when it was observed.nodeHealthMap *nodeHealthMap// evictorLock protects zonePodEvictor and zoneNoExecuteTainter.// TODO(#83954): API calls shouldn"t be executed under the lock.evictorLock     sync.MutexnodeEvictionMap *nodeEvictionMap// workers that evicts pods from unresponsive nodes.zonePodEvictor map[string]*scheduler.RateLimitedTimedQueue// workers that are responsible for tainting nodes.zoneNoExecuteTainter map[string]*scheduler.RateLimitedTimedQueuenodesToRetry sync.MapzoneStates map[string]ZoneStatedaemonSetStore          appsv1listers.DaemonSetListerdaemonSetInformerSynced cache.InformerSyncedleaseLister         coordlisters.LeaseListerleaseInformerSynced cache.InformerSyncednodeLister          corelisters.NodeListernodeInformerSynced  cache.InformerSyncedgetPodsAssignedToNode func(nodeName string) ([]*v1.Pod, error)recorder record.EventRecorder// Value controlling Controller monitoring period, i.e. how often does Controller// check node health signal posted from kubelet. This value should be lower than// nodeMonitorGracePeriod.// TODO: Change node health monitor to watch based.nodeMonitorPeriod time.Duration// When node is just created, e.g. cluster bootstrap or node creation, we give// a longer grace period.nodeStartupGracePeriod time.Duration// Controller will not proactively sync node health, but will monitor node// health signal updated from kubelet. There are 2 kinds of node healthiness// signals: NodeStatus and NodeLease. NodeLease signal is generated only when// NodeLease feature is enabled. If it doesn"t receive update for this amount// of time, it will start posting "NodeReady==ConditionUnknown". The amount of// time before which Controller start evicting pods is controlled via flag// "pod-eviction-timeout".// Note: be cautious when changing the constant, it must work with// nodeStatusUpdateFrequency in kubelet and renewInterval in NodeLease// controller. The node health signal update frequency is the minimal of the// two.// There are several constraints:// 1. nodeMonitorGracePeriod must be N times more than  the node health signal//    update frequency, where N means number of retries allowed for kubelet to//    post node status/lease. It is pointless to make nodeMonitorGracePeriod//    be less than the node health signal update frequency, since there will//    only be fresh values from Kubelet at an interval of node health signal//    update frequency. The constant must be less than podEvictionTimeout.// 2. nodeMonitorGracePeriod can"t be too large for user experience - larger//    value takes longer for user to see up-to-date node health.nodeMonitorGracePeriod time.DurationpodEvictionTimeout          time.DurationevictionLimiterQPS          float32secondaryEvictionLimiterQPS float32largeClusterThreshold       int32unhealthyZoneThreshold      float32// if set to true Controller will start TaintManager that will evict Pods from// tainted nodes, if they"re not tolerated.runTaintManager bool// if set to true Controller will taint Nodes with "TaintNodeNotReady" and "TaintNodeUnreachable"// taints instead of evicting Pods itself.useTaintBasedEvictions boolnodeUpdateQueue workqueue.InterfacepodUpdateQueue  workqueue.RateLimitingInterface}

2.2 初始化逻辑分析

NewNodeLifecycleController函数的主要逻辑为：（1）初始化Controller结构体，代表NodeLifecycleController；（2）给podInformer注册EventHandler（部分逻辑与TaintManager相关）；（3）判断是否开启污点驱逐，即--enable-taint-manager启动参数值是否配置为true，是则初始化TaintManager并赋值给Controller的taintManager属性，随后给nodeInformer注册TaintManager相关的EventHandler；（4）给nodeInformer注册EventHandler；

// pkg/controller/nodelifecycle/node_lifecycle_controller.gofunc NewNodeLifecycleController(leaseInformer coordinformers.LeaseInformer,podInformer coreinformers.PodInformer,nodeInformer coreinformers.NodeInformer,daemonSetInformer appsv1informers.DaemonSetInformer,kubeClient clientset.Interface,nodeMonitorPeriod time.Duration,nodeStartupGracePeriod time.Duration,nodeMonitorGracePeriod time.Duration,podEvictionTimeout time.Duration,evictionLimiterQPS float32,secondaryEvictionLimiterQPS float32,largeClusterThreshold int32,unhealthyZoneThreshold float32,runTaintManager bool,useTaintBasedEvictions bool,) (*Controller, error) {...    // (1)初始化`Controller`结构体；  nc := &Controller{kubeClient:                  kubeClient,now:                         metav1.Now,knownNodeSet:                make(map[string]*v1.Node),nodeHealthMap:               newNodeHealthMap(),nodeEvictionMap:             newNodeEvictionMap(),recorder:                    recorder,nodeMonitorPeriod:           nodeMonitorPeriod,nodeStartupGracePeriod:      nodeStartupGracePeriod,nodeMonitorGracePeriod:      nodeMonitorGracePeriod,zonePodEvictor:              make(map[string]*scheduler.RateLimitedTimedQueue),zoneNoExecuteTainter:        make(map[string]*scheduler.RateLimitedTimedQueue),nodesToRetry:                sync.Map{},zoneStates:                  make(map[string]ZoneState),podEvictionTimeout:          podEvictionTimeout,evictionLimiterQPS:          evictionLimiterQPS,secondaryEvictionLimiterQPS: secondaryEvictionLimiterQPS,largeClusterThreshold:       largeClusterThreshold,unhealthyZoneThreshold:      unhealthyZoneThreshold,runTaintManager:             runTaintManager,useTaintBasedEvictions:      useTaintBasedEvictions && runTaintManager,nodeUpdateQueue:             workqueue.NewNamed("node_lifecycle_controller"),podUpdateQueue:              workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), "node_lifecycle_controller_pods"),}if useTaintBasedEvictions {klog.Infof("Controller is using taint based evictions.")}nc.enterPartialDisruptionFunc = nc.ReducedQPSFuncnc.enterFullDisruptionFunc = nc.HealthyQPSFuncnc.computeZoneStateFunc = nc.ComputeZoneState    // (2)给`podInformer`注册`EventHandler`（部分逻辑与`TaintManager`相关）；podInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{AddFunc: func(obj interface{}) {pod := obj.(*v1.Pod)nc.podUpdated(nil, pod)if nc.taintManager != nil {nc.taintManager.PodUpdated(nil, pod)}},UpdateFunc: func(prev, obj interface{}) {prevPod := prev.(*v1.Pod)newPod := obj.(*v1.Pod)nc.podUpdated(prevPod, newPod)if nc.taintManager != nil {nc.taintManager.PodUpdated(prevPod, newPod)}},DeleteFunc: func(obj interface{}) {pod, isPod := obj.(*v1.Pod)// We can get DeletedFinalStateUnknown instead of *v1.Pod here and we need to handle that correctly.if !isPod {deletedState, ok := obj.(cache.DeletedFinalStateUnknown)if !ok {klog.Errorf("Received unexpected object: %v", obj)return}pod, ok = deletedState.Obj.(*v1.Pod)if !ok {klog.Errorf("DeletedFinalStateUnknown contained non-Pod object: %v", deletedState.Obj)return}}nc.podUpdated(pod, nil)if nc.taintManager != nil {nc.taintManager.PodUpdated(pod, nil)}},})nc.podInformerSynced = podInformer.Informer().HasSyncedpodInformer.Informer().AddIndexers(cache.Indexers{nodeNameKeyIndex: func(obj interface{}) ([]string, error) {pod, ok := obj.(*v1.Pod)if !ok {return []string{}, nil}if len(pod.Spec.NodeName) == 0 {return []string{}, nil}return []string{pod.Spec.NodeName}, nil},})podIndexer := podInformer.Informer().GetIndexer()nc.getPodsAssignedToNode = func(nodeName string) ([]*v1.Pod, error) {objs, err := podIndexer.ByIndex(nodeNameKeyIndex, nodeName)if err != nil {return nil, err}pods := make([]*v1.Pod, 0, len(objs))for _, obj := range objs {pod, ok := obj.(*v1.Pod)if !ok {continue}pods = append(pods, pod)}return pods, nil}nc.podLister = podInformer.Lister()    // (3)判断是否开启污点驱逐，即`--enable-taint-manager`启动参数值是否配置为true，是则初始化`TaintManager`并赋值给`Controller`的`taintManager`属性，随后给nodeInformer注册`TaintManager`相关的`EventHandler`；  if nc.runTaintManager {podGetter := func(name, namespace string) (*v1.Pod, error) { return nc.podLister.Pods(namespace).Get(name) }nodeLister := nodeInformer.Lister()nodeGetter := func(name string) (*v1.Node, error) { return nodeLister.Get(name) }nc.taintManager = scheduler.NewNoExecuteTaintManager(kubeClient, podGetter, nodeGetter, nc.getPodsAssignedToNode)nodeInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{AddFunc: nodeutil.CreateAddNodeHandler(func(node *v1.Node) error {nc.taintManager.NodeUpdated(nil, node)return nil}),UpdateFunc: nodeutil.CreateUpdateNodeHandler(func(oldNode, newNode *v1.Node) error {nc.taintManager.NodeUpdated(oldNode, newNode)return nil}),DeleteFunc: nodeutil.CreateDeleteNodeHandler(func(node *v1.Node) error {nc.taintManager.NodeUpdated(node, nil)return nil}),})}        // (4) 给`nodeInformer`注册`EventHandler`；  klog.Infof("Controller will reconcile labels.")nodeInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{AddFunc: nodeutil.CreateAddNodeHandler(func(node *v1.Node) error {nc.nodeUpdateQueue.Add(node.Name)nc.nodeEvictionMap.registerNode(node.Name)return nil}),UpdateFunc: nodeutil.CreateUpdateNodeHandler(func(_, newNode *v1.Node) error {nc.nodeUpdateQueue.Add(newNode.Name)return nil}),DeleteFunc: nodeutil.CreateDeleteNodeHandler(func(node *v1.Node) error {nc.nodesToRetry.Delete(node.Name)nc.nodeEvictionMap.unregisterNode(node.Name)return nil}),})nc.leaseLister = leaseInformer.Lister()nc.leaseInformerSynced = leaseInformer.Informer().HasSyncednc.nodeLister = nodeInformer.Lister()nc.nodeInformerSynced = nodeInformer.Informer().HasSyncednc.daemonSetStore = daemonSetInformer.Lister()nc.daemonSetInformerSynced = daemonSetInformer.Informer().HasSyncedreturn nc, nil}

3.处理逻辑分析

Run方法作为NodeLifecycleController的处理逻辑分析入口，其主要逻辑为：（1）等待leaseInformer、nodeInformer、podInformer、daemonSetInformer中的cache同步完成；

（2）判断是否开启污点驱逐，是则拉起一个goroutine，调用nc.taintManager.Run方法，启动taintManager；

（3）启动8个goroutine，即8个worker，循环调用nc.doNodeProcessingPassWorker方法，用于处理nc.nodeUpdateQueue队列；nc.doNodeProcessingPassWorker方法有两个作用：（3-1）调用nc.doNoScheduleTaintingPass方法，根据node.Status.Conditions与node.Spec.Unschedulable的值来更新node.Spec.Taints，主要是设置Effect为noschedule的taint；（3-2）调用nc.reconcileNodeLabels方法，处理node对象中os和arch相关的label；

（4）启动4个goroutine，即4个worker，循环调用nc.doPodProcessingWorker方法，用于处理nc.podUpdateQueue队列；nc.doPodProcessingWorker方法做以下两个操作：（4-1）当污点驱逐未开启时，判断node对象的status，当node的ready Condition为false或unknown且已经持续了至少nc.podEvictionTimeout的时间时，对该node上的pod做驱逐（删除）操作；（4-2）如果node的ready condition值不为true，则将pod的ready condition更新为false；

（5）判断nc.useTaintBasedEvictions是否为true，即是否开启污点驱逐，是则启动goroutine并循环调用nc.doNoExecuteTaintingPass；nc.doNoExecuteTaintingPass方法主要作用是根据node.Status.Conditions的值来更新node.Spec.Taints，主要是设置Effect为noExecute的taint；

（6）未开启污点驱逐时，启动goroutine并循环调用nc.doEvictionPass；nc.doEvictionPass方法主要作用是从nc.zonePodEvictor中获取node，然后驱逐（删除）该node上除daemonset pod外的所有pod；

（7）启动goroutine，间隔nc.nodeMonitorPeriod时间（即kcm启动参数--node-monitor-period，默认值5秒）循环调用nc.monitorNodeHealth方法；nc.monitorNodeHealth方法的主要作用是持续监控node的状态，根据集群中不同zone下unhealthy数量的node，以及kcm启动参数中驱逐速率的相关配置，给不同的zone设置不同的驱逐速率（该驱逐速率对是否开启污点驱逐均生效），且当node心跳上报（node lease的更新时间）距离上一次上报时间已经超过nodeMonitorGracePeriod（刚启动则为nodeStartupGracePeriod），更新node对象的ready condition值，并做相应的驱逐处理：（7-1）当开启了污点驱逐，且node的ready condition不为true时，添加NoExcute污点，并将该node放入zoneNoExecuteTainter中，由taintManager来做驱逐操作；（7-2）当没开启污点驱逐，且node的ready condition不为true持续了podEvictionTimeout时间，则开始驱逐pod的操作；

// pkg/controller/nodelifecycle/node_lifecycle_controller.gofunc (nc *Controller) Run(stopCh <-chan struct{}) {defer utilruntime.HandleCrash()klog.Infof("Starting node controller")defer klog.Infof("Shutting down node controller")if !cache.WaitForNamedCacheSync("taint", stopCh, nc.leaseInformerSynced, nc.nodeInformerSynced, nc.podInformerSynced, nc.daemonSetInformerSynced) {return}if nc.runTaintManager {go nc.taintManager.Run(stopCh)}// Close node update queue to cleanup go routine.defer nc.nodeUpdateQueue.ShutDown()defer nc.podUpdateQueue.ShutDown()// Start workers to reconcile labels and/or update NoSchedule taint for nodes.for i := 0; i < scheduler.UpdateWorkerSize; i++ {// Thanks to "workqueue", each worker just need to get item from queue, because// the item is flagged when got from queue: if new event come, the new item will// be re-queued until "Done", so no more than one worker handle the same item and// no event missed.go wait.Until(nc.doNodeProcessingPassWorker, time.Second, stopCh)}for i := 0; i < podUpdateWorkerSize; i++ {go wait.Until(nc.doPodProcessingWorker, time.Second, stopCh)}if nc.useTaintBasedEvictions {// Handling taint based evictions. Because we don"t want a dedicated logic in TaintManager for NC-originated// taints and we normally don"t rate limit evictions caused by taints, we need to rate limit adding taints.go wait.Until(nc.doNoExecuteTaintingPass, scheduler.NodeEvictionPeriod, stopCh)} else {// Managing eviction of nodes:// When we delete pods off a node, if the node was not empty at the time we then// queue an eviction watcher. If we hit an error, retry deletion.go wait.Until(nc.doEvictionPass, scheduler.NodeEvictionPeriod, stopCh)}// Incorporate the results of node health signal pushed from kubelet to master.go wait.Until(func() {if err := nc.monitorNodeHealth(); err != nil {klog.Errorf("Error monitoring node health: %v", err)}}, nc.nodeMonitorPeriod, stopCh)<-stopCh}

3.1 nc.taintManager.Run

taintManager的主要功能为：当某个node被打上NoExecute污点后，其上面的pod如果不能容忍该污点，则taintManager将会驱逐这些pod，而新建的pod也需要容忍该污点才能调度到该node上；

通过kcm启动参数--enable-taint-manager来确定是否启动taintManager，true时启动（启动参数默认值为true）；

kcm启动参数--feature-gates=TaintBasedEvictions=xxx，默认值true，配合--enable-taint-manager共同作用，两者均为true，才会开启污点驱逐；

taintManager部分的内容比较多，将在后面单独一遍文章进行分析；

3.2 nc.doNodeProcessingPassWorker

nc.doNodeProcessingPassWorker方法有两个作用：（1）调用nc.doNoScheduleTaintingPass方法，根据node.Status.Conditions与node.Spec.Unschedulable的值来更新node.Spec.Taints，主要是设置Effect为noschedule的taint；（2）调用nc.reconcileNodeLabels方法，处理node对象中os和arch相关的label；

主要逻辑：（1）循环消费nodeUpdateQueue队列，从队列中获取一个nodeName；（2）调用nc.doNoScheduleTaintingPass，对node的taint进行处理；（3）调用nc.reconcileNodeLabels，对node对象中os和arch相关的label进行处理；

// pkg/controller/nodelifecycle/node_lifecycle_controller.gofunc (nc *Controller) doNodeProcessingPassWorker() {for {obj, shutdown := nc.nodeUpdateQueue.Get()// "nodeUpdateQueue" will be shutdown when "stopCh" closed;// we do not need to re-check "stopCh" again.if shutdown {return}nodeName := obj.(string)if err := nc.doNoScheduleTaintingPass(nodeName); err != nil {klog.Errorf("Failed to taint NoSchedule on node <%s>, requeue it: %v", nodeName, err)// TODO(k82cn): Add nodeName back to the queue}// TODO: re-evaluate whether there are any labels that need to be// reconcile in 1.19. Remove this function if it"s no longer necessary.if err := nc.reconcileNodeLabels(nodeName); err != nil {klog.Errorf("Failed to reconcile labels for node <%s>, requeue it: %v", nodeName, err)// TODO(yujuhong): Add nodeName back to the queue}nc.nodeUpdateQueue.Done(nodeName)}}

3.2.1 nc.doNoScheduleTaintingPass

nc.doNoScheduleTaintingPass方法主要作用是根据node.Status.Conditions与node.Spec.Unschedulable的值来更新node.Spec.Taints，主要是设置Effect为noschedule的taint；

主要逻辑：（1）调用nc.nodeLister.Get，从informer本地缓存中获取node对象，不存在则直接return；

（2）根据node.Status.Conditions的值，获得相应的taints；（2-1）node.status.Conditions中有type为ready的condition。如果这个condition.status为fasle，设置key为node.kubernetes.io/not-ready，Effect为noschedule的taint；如果这个condition.status值为unknown，设置key为node.kubernetes.io/unreachable，Effect为noschedule的taint；（2-2）node.status.Conditions中有type为MemoryPressure的condition。如果这个condition.status为true，设置key为node.kubernetes.io/memory-pressure，Effect为noschedule的taint；（2-3）node.status.Conditions中有type为DiskPressure的condition。如果这个condition.status为true，设置key为node.kubernetes.io/disk-pressure，Effect为noschedule的taint；（2-4）node.status.Conditions中有type为NetworkUnavailable的condition。如果这个condition.status为true，设置key为node.kubernetes.io/network-unavailable，Effect为noschedule的taint；（2-5）node.status.Conditions中有type为PIDPressure的condition。如果这个condition.status为true，设置key为node.kubernetes.io/pid-pressure，Effect为noschedule的taint；

（3）如果node.Spec.Unschedulable值为true，则再追加key为node.kubernetes.io/unschedulable，Effect为noschedule的taint到taints中；

（4）调用nodeutil.SwapNodeControllerTaint，更新node的taints；

// pkg/controller/nodelifecycle/node_lifecycle_controller.govar(    ...    nodeConditionToTaintKeyStatusMap = map[v1.NodeConditionType]map[v1.ConditionStatus]string{v1.NodeReady: {v1.ConditionFalse:   v1.TaintNodeNotReady,v1.ConditionUnknown: v1.TaintNodeUnreachable,},v1.NodeMemoryPressure: {v1.ConditionTrue: v1.TaintNodeMemoryPressure,},v1.NodeDiskPressure: {v1.ConditionTrue: v1.TaintNodeDiskPressure,},v1.NodeNetworkUnavailable: {v1.ConditionTrue: v1.TaintNodeNetworkUnavailable,},v1.NodePIDPressure: {v1.ConditionTrue: v1.TaintNodePIDPressure,},}    ...)func (nc *Controller) doNoScheduleTaintingPass(nodeName string) error {node, err := nc.nodeLister.Get(nodeName)if err != nil {// If node not found, just ignore it.if apierrors.IsNotFound(err) {return nil}return err}// Map node"s condition to Taints.var taints []v1.Taintfor _, condition := range node.Status.Conditions {if taintMap, found := nodeConditionToTaintKeyStatusMap[condition.Type]; found {if taintKey, found := taintMap[condition.Status]; found {taints = append(taints, v1.Taint{Key:    taintKey,Effect: v1.TaintEffectNoSchedule,})}}}if node.Spec.Unschedulable {// If unschedulable, append related taint.taints = append(taints, v1.Taint{Key:    v1.TaintNodeUnschedulable,Effect: v1.TaintEffectNoSchedule,})}// Get exist taints of node.nodeTaints := taintutils.TaintSetFilter(node.Spec.Taints, func(t *v1.Taint) bool {// only NoSchedule taints are candidates to be compared with "taints" laterif t.Effect != v1.TaintEffectNoSchedule {return false}// Find unschedulable taint of node.if t.Key == v1.TaintNodeUnschedulable {return true}// Find node condition taints of node._, found := taintKeyToNodeConditionMap[t.Key]return found})taintsToAdd, taintsToDel := taintutils.TaintSetDiff(taints, nodeTaints)// If nothing to add not delete, return true directly.if len(taintsToAdd) == 0 && len(taintsToDel) == 0 {return nil}if !nodeutil.SwapNodeControllerTaint(nc.kubeClient, taintsToAdd, taintsToDel, node) {return fmt.Errorf("failed to swap taints of node %+v", node)}return nil}

3.2.2 nc.reconcileNodeLabels

nc.reconcileNodeLabels方法主要是处理node对象中，os和arch相关的label，os和arch相关的label在kubelet向apiserver注册node的时候会带上；

主要逻辑：（1）从informer缓存中获取node对象，不存在则直接return；（2）如果node的label为空，则直接return；（3）如果node对象存在key为“beta.kubernetes.io/os”的label ，则设置key为“kubernetes.io/os"、value值一样的label；（4）如果node对象存在key为“beta.kubernetes.io/arch”的label，则设置key为“kubernetes.io/arch"、value值一样的label；

3.3 nc.doPodProcessingWorker

nc.doPodProcessingWorker方法判断node对象的status，当node的ready Condition为false或unknown且已经持续了至少nc.podEvictionTimeout的时间时，对该node上的pod做驱逐（删除）操作，并且如果node的ready condition值不为true，则将pod的ready condition更新为false；

需要注意的是，当启用了taint manager时，pod的驱逐由taint manager进行处理，这里就不再进行pod的驱逐处理。

主要逻辑：（1）循环消费podUpdateQueue队列，从队列中获取一个nodeName；（2）调用nc.processPod，做进一步处理；

// pkg/controller/nodelifecycle/node_lifecycle_controller.gofunc (nc *Controller) doPodProcessingWorker() {for {obj, shutdown := nc.podUpdateQueue.Get()// "podUpdateQueue" will be shutdown when "stopCh" closed;// we do not need to re-check "stopCh" again.if shutdown {return}podItem := obj.(podUpdateItem)nc.processPod(podItem)}}

3.3.1 nc.processPod

nc.processPod方法主要逻辑：（1）从informer本地缓存中获取pod对象；（2）获取pod所在nodeName，并根据nodeName调用nc.nodeHealthMap.getDeepCopy获取nodeHealth，如nodeHealth为空则直接return；（3）调用nodeutil.GetNodeCondition，获取nodeHealth.status中node的ready condition，如果获取不到则直接return；（4）判断taint manager是否启用，没启用则调用nc.processNoTaintBaseEviction对pod做进一步处理（驱逐逻辑）；（5）如果node的ready condition值不为true，则调用nodeutil.MarkPodsNotReady将pod的ready condition更新为false；

注意：当启用taint manager时，pod的驱逐由taint manager进行处理，所以不在这里处理。

// pkg/controller/nodelifecycle/node_lifecycle_controller.gofunc (nc *Controller) processPod(podItem podUpdateItem) {defer nc.podUpdateQueue.Done(podItem)pod, err := nc.podLister.Pods(podItem.namespace).Get(podItem.name)if err != nil {if apierrors.IsNotFound(err) {// If the pod was deleted, there is no need to requeue.return}klog.Warningf("Failed to read pod %v/%v: %v.", podItem.namespace, podItem.name, err)nc.podUpdateQueue.AddRateLimited(podItem)return}nodeName := pod.Spec.NodeNamenodeHealth := nc.nodeHealthMap.getDeepCopy(nodeName)if nodeHealth == nil {// Node data is not gathered yet or node has beed removed in the meantime.// Pod will be handled by doEvictionPass method.return}node, err := nc.nodeLister.Get(nodeName)if err != nil {klog.Warningf("Failed to read node %v: %v.", nodeName, err)nc.podUpdateQueue.AddRateLimited(podItem)return}_, currentReadyCondition := nodeutil.GetNodeCondition(nodeHealth.status, v1.NodeReady)if currentReadyCondition == nil {// Lack of NodeReady condition may only happen after node addition (or if it will be maliciously deleted).// In both cases, the pod will be handled correctly (evicted if needed) during processing// of the next node update event.return}pods := []*v1.Pod{pod}// In taint-based eviction mode, only node updates are processed by NodeLifecycleController.// Pods are processed by TaintManager.if !nc.useTaintBasedEvictions {if err := nc.processNoTaintBaseEviction(node, currentReadyCondition, nc.nodeMonitorGracePeriod, pods); err != nil {klog.Warningf("Unable to process pod %+v eviction from node %v: %v.", podItem, nodeName, err)nc.podUpdateQueue.AddRateLimited(podItem)return}}if currentReadyCondition.Status != v1.ConditionTrue {if err := nodeutil.MarkPodsNotReady(nc.kubeClient, pods, nodeName); err != nil {klog.Warningf("Unable to mark pod %+v NotReady on node %v: %v.", podItem, nodeName, err)nc.podUpdateQueue.AddRateLimited(podItem)}}}

3.3.2 nc.processNoTaintBaseEviction

nc.processNoTaintBaseEviction方法主要逻辑：（1）当node的ready Condition为false或unknown且已经持续了至少nc.podEvictionTimeout的时间时，调用nc.evictPods方法，将node加入到nc.zonePodEvictor队列中，由其他worker消费该队列，对该node上的pod做驱逐（删除）操作；（2）当node的ready Condition为true时，调用nc.cancelPodEviction方法，将该node从nc.zonePodEvictor队列中移除，代表取消驱逐该node上的pod；

// pkg/controller/nodelifecycle/node_lifecycle_controller.gofunc (nc *Controller) processNoTaintBaseEviction(node *v1.Node, observedReadyCondition *v1.NodeCondition, gracePeriod time.Duration, pods []*v1.Pod) error {decisionTimestamp := nc.now()nodeHealthData := nc.nodeHealthMap.getDeepCopy(node.Name)if nodeHealthData == nil {return fmt.Errorf("health data doesn"t exist for node %q", node.Name)}// Check eviction timeout against decisionTimestampswitch observedReadyCondition.Status {case v1.ConditionFalse:if decisionTimestamp.After(nodeHealthData.readyTransitionTimestamp.Add(nc.podEvictionTimeout)) {enqueued, err := nc.evictPods(node, pods)if err != nil {return err}if enqueued {klog.V(2).Infof("Node is NotReady. Adding Pods on Node %s to eviction queue: %v is later than %v + %v",node.Name,decisionTimestamp,nodeHealthData.readyTransitionTimestamp,nc.podEvictionTimeout,)}}case v1.ConditionUnknown:if decisionTimestamp.After(nodeHealthData.probeTimestamp.Add(nc.podEvictionTimeout)) {enqueued, err := nc.evictPods(node, pods)if err != nil {return err}if enqueued {klog.V(2).Infof("Node is unresponsive. Adding Pods on Node %s to eviction queues: %v is later than %v + %v",node.Name,decisionTimestamp,nodeHealthData.readyTransitionTimestamp,nc.podEvictionTimeout-gracePeriod,)}}case v1.ConditionTrue:if nc.cancelPodEviction(node) {klog.V(2).Infof("Node %s is ready again, cancelled pod eviction", node.Name)}}return nil}

3.3.3 nc.evictPods

nc.evictPods方法不列出源码，只需要知道：该方法主要是将node加入到nc.zonePodEvictor队列中，由其他worker消费该队列，对该node上的pod做驱逐（删除）操作；

3.3.4 消费nc.zonePodEvictor队列-nc.doEvictionPass

nc.doEvictionPass方法负责消费nc.zonePodEvictor队列，调用nodeutil.DeletePods来将node上的pod驱逐（删除）掉；

// pkg/controller/nodelifecycle/node_lifecycle_controller.gofunc (nc *Controller) doEvictionPass() {nc.evictorLock.Lock()defer nc.evictorLock.Unlock()for k := range nc.zonePodEvictor {    nc.zonePodEvictor[k].Try(func(value scheduler.TimedValue) (bool, time.Duration) {        ...        remaining, err := nodeutil.DeletePods(nc.kubeClient, pods, nc.recorder, value.Value, nodeUID, nc.daemonSetStore)        ...    })}}

// pkg/controller/util/node/controller_utils.gofunc DeletePods(...) ... {    ...    for i := range pods {        if err := kubeClient.CoreV1().Pods(pod.Namespace).Delete(pod.Name, nil); err != nil {        ...    }    ...}

3.4 nc.doNoExecuteTaintingPass

nc.doNoExecuteTaintingPass方法主要作用是根据node.Status.Conditions的值来更新node.Spec.Taints，主要是设置Effect为noExecute的taint；

主要逻辑为循环遍历nc.zoneNoExecuteTainter，然后做相关处理：（1）从nc.zoneNoExecuteTainter中取出一个node，然后从informer本地缓存中获取该node对象；（2）获取node对象ready condition的值并做判断，如为false则构建key为node.kubernetes.io/not-ready，Effect为NoExecute的taint；如为unknown则构建key为node.kubernetes.io/unreachable，Effect为NoExecute的taint；（3）最后调用nodeutil.SwapNodeControllerTaint，将构造好的taint更新到node对象中（这里注意，上述两个NoExecute的taint在node对象中，同一时间只会存在一个，一个添加到node对象中时，会把另一个移除）；

// pkg/controller/nodelifecycle/node_lifecycle_controller.gofunc (nc *Controller) doNoExecuteTaintingPass() {nc.evictorLock.Lock()defer nc.evictorLock.Unlock()for k := range nc.zoneNoExecuteTainter {// Function should return "false" and a time after which it should be retried, or "true" if it shouldn"t (it succeeded).nc.zoneNoExecuteTainter[k].Try(func(value scheduler.TimedValue) (bool, time.Duration) {node, err := nc.nodeLister.Get(value.Value)if apierrors.IsNotFound(err) {klog.Warningf("Node %v no longer present in nodeLister!", value.Value)return true, 0} else if err != nil {klog.Warningf("Failed to get Node %v from the nodeLister: %v", value.Value, err)// retry in 50 millisecondreturn false, 50 * time.Millisecond}_, condition := nodeutil.GetNodeCondition(&node.Status, v1.NodeReady)// Because we want to mimic NodeStatus.Condition["Ready"] we make "unreachable" and "not ready" taints mutually exclusive.taintToAdd := v1.Taint{}oppositeTaint := v1.Taint{}switch condition.Status {case v1.ConditionFalse:taintToAdd = *NotReadyTaintTemplateoppositeTaint = *UnreachableTaintTemplatecase v1.ConditionUnknown:taintToAdd = *UnreachableTaintTemplateoppositeTaint = *NotReadyTaintTemplatedefault:// It seems that the Node is ready again, so there"s no need to taint it.klog.V(4).Infof("Node %v was in a taint queue, but it"s ready now. Ignoring taint request.", value.Value)return true, 0}result := nodeutil.SwapNodeControllerTaint(nc.kubeClient, []*v1.Taint{&taintToAdd}, []*v1.Taint{&oppositeTaint}, node)if result {//count the evictionsNumberzone := utilnode.GetZoneKey(node)evictionsNumber.WithLabelValues(zone).Inc()}return result, 0})}}

3.5 nc.doEvictionPass

nc.doEvictionPass方法主要作用是从nc.zonePodEvictor中获取node，然后驱逐（删除）该node上除daemonset pod外的所有pod；

主要逻辑为循环遍历nc.zonePodEvictor，然后做相关处理：（1）从nc.zonePodEvictor中取出一个node，然后从informer本地缓存中获取该node对象；（2）调用nc.getPodsAssignedToNode，获取该node上的所有pod；（3）调用nodeutil.DeletePods，删除该node上除daemonset pod外的所有的pod；

// pkg/controller/nodelifecycle/node_lifecycle_controller.gofunc (nc *Controller) doEvictionPass() {nc.evictorLock.Lock()defer nc.evictorLock.Unlock()for k := range nc.zonePodEvictor {// Function should return "false" and a time after which it should be retried, or "true" if it shouldn"t (it succeeded).nc.zonePodEvictor[k].Try(func(value scheduler.TimedValue) (bool, time.Duration) {node, err := nc.nodeLister.Get(value.Value)if apierrors.IsNotFound(err) {klog.Warningf("Node %v no longer present in nodeLister!", value.Value)} else if err != nil {klog.Warningf("Failed to get Node %v from the nodeLister: %v", value.Value, err)}nodeUID, _ := value.UID.(string)pods, err := nc.getPodsAssignedToNode(value.Value)if err != nil {utilruntime.HandleError(fmt.Errorf("unable to list pods from node %q: %v", value.Value, err))return false, 0}remaining, err := nodeutil.DeletePods(nc.kubeClient, pods, nc.recorder, value.Value, nodeUID, nc.daemonSetStore)if err != nil {// We are not setting eviction status here.// New pods will be handled by zonePodEvictor retry// instead of immediate pod eviction.utilruntime.HandleError(fmt.Errorf("unable to evict node %q: %v", value.Value, err))return false, 0}if !nc.nodeEvictionMap.setStatus(value.Value, evicted) {klog.V(2).Infof("node %v was unregistered in the meantime - skipping setting status", value.Value)}if remaining {klog.Infof("Pods awaiting deletion due to Controller eviction")}if node != nil {zone := utilnode.GetZoneKey(node)evictionsNumber.WithLabelValues(zone).Inc()}return true, 0})}}

3.6 nc.monitorNodeHealth

nc.monitorNodeHealth方法的主要作用是持续监控node的状态，根据集群中不同zone下unhealthy数量的node，以及kcm启动参数中驱逐速率的相关配置，给不同的zone设置不同的驱逐速率（该驱逐速率对是否开启污点驱逐均生效），且当node心跳上报（node lease的更新时间）距离上一次上报时间已经超过nodeMonitorGracePeriod（刚启动则为nodeStartupGracePeriod），更新node对象的ready condition值，并做相应的驱逐处理：（1）当开启了污点驱逐，且node的ready condition不为true时，添加NoExcute污点，并将该node放入zoneNoExecuteTainter中，由taintManager来做驱逐操作；（2）当没开启污点驱逐，且node的ready condition不为true持续了podEvictionTimeout时间，则开始驱逐pod的操作；

主要逻辑：（1）从informer本地缓存中获取所有node对象；

（2）调用nc.classifyNodes，将这些node对象分为added、deleted、newZoneRepresentatives三类，即新增的、被删除的、属于新的zone三类，并对每一类做不同的逻辑处理（根据node对象的region与zone label，为每一个node划分一个zoneStates），zoneStates有Initial、Normal、FullDisruption、PartialDisruption四种，新增加的 node默认zoneStates为Initial，其余的几个zoneStates分别对应着不同的驱逐速率；

（3）遍历node对象列表，对每个node进行处理；（3-1）调用nc.tryUpdateNodeHealth，根据当前获取的node对象的ready condition值、node lease的更新时间等来更新nc.nodeHealthMap中的数据、更新node的condition值，并获取该node的gracePeriod、observedReadyCondition、currentReadyCondition值，observedReadyCondition可以理解为该node上一次探测时的状态，currentReadyCondition为本次计算出来的状态；（3-2）如果currentReadyCondition不为空，则调用nc.getPodsAssignedToNode，获取该node上的所有pod列表；（3-3）如果nc.useTaintBasedEvictions为true，即开启了污点驱逐，则调用nc.processTaintBaseEviction，当node的ready condition属性值为false时去除Unrearchable的污点而添加Notready的污点，并将该node加入zoneNoExecuteTainter队列中；为unknown时去除Notready的污点而添加Unrearchable的污点，并将该node加入zoneNoExecuteTainter队列中；为true时去除Notready、Unrearchable的污点，然后将该node从zoneNoExecuteTainter队列中移除；（3-4）如果nc.useTaintBasedEvictions为false，则调用nc.processNoTaintBaseEviction，做进一步的驱逐逻辑处理：当node的ready condition属性值为false时，判断距该node上一次的readyTransitionTimestamp时间是否超过了 podEvictionTimeout，是则将该node加入到zonePodEvictor队列中，最终该node上的pod会被驱逐；当node的ready condition属性值为unknow时，判断距该node上一次的probeTimestamp时间是否超过了 podEvictionTimeout，是则将该node加入到zonePodEvictor队列中，最终该node上的pod会被驱逐；当node的ready condition属性值为true时，调用nc.cancelPodEviction，将该node从zonePodEvictor队列中移除，代表不再对该node上的pod执行驱逐操作；（3-5）当node对象的Ready Condition值由true变为false时，则调用nodeutil.MarkAllPodsNotReady，将该node上的所有pod标记为notReady；

（4）调用nc.handleDisruption，根据集群中不同zone下unhealthy数量的node，以及kcm启动参数中驱逐速率的相关配置，给不同的zone设置不同的驱逐速率（该驱逐速率对是否开启污点驱逐均生效）；nc.handleDisruption方法暂不展开分析，可自行查看；

// pkg/controller/nodelifecycle/node_lifecycle_controller.gofunc (nc *Controller) monitorNodeHealth() error {// We are listing nodes from local cache as we can tolerate some small delays// comparing to state from etcd and there is eventual consistency anyway.nodes, err := nc.nodeLister.List(labels.Everything())if err != nil {return err}added, deleted, newZoneRepresentatives := nc.classifyNodes(nodes)for i := range newZoneRepresentatives {nc.addPodEvictorForNewZone(newZoneRepresentatives[i])}for i := range added {klog.V(1).Infof("Controller observed a new Node: %#v", added[i].Name)nodeutil.RecordNodeEvent(nc.recorder, added[i].Name, string(added[i].UID), v1.EventTypeNormal, "RegisteredNode", fmt.Sprintf("Registered Node %v in Controller", added[i].Name))nc.knownNodeSet[added[i].Name] = added[i]nc.addPodEvictorForNewZone(added[i])if nc.useTaintBasedEvictions {nc.markNodeAsReachable(added[i])} else {nc.cancelPodEviction(added[i])}}for i := range deleted {klog.V(1).Infof("Controller observed a Node deletion: %v", deleted[i].Name)nodeutil.RecordNodeEvent(nc.recorder, deleted[i].Name, string(deleted[i].UID), v1.EventTypeNormal, "RemovingNode", fmt.Sprintf("Removing Node %v from Controller", deleted[i].Name))delete(nc.knownNodeSet, deleted[i].Name)}zoneToNodeConditions := map[string][]*v1.NodeCondition{}for i := range nodes {var gracePeriod time.Durationvar observedReadyCondition v1.NodeConditionvar currentReadyCondition *v1.NodeConditionnode := nodes[i].DeepCopy()if err := wait.PollImmediate(retrySleepTime, retrySleepTime*scheduler.NodeHealthUpdateRetry, func() (bool, error) {gracePeriod, observedReadyCondition, currentReadyCondition, err = nc.tryUpdateNodeHealth(node)if err == nil {return true, nil}name := node.Namenode, err = nc.kubeClient.CoreV1().Nodes().Get(name, metav1.GetOptions{})if err != nil {klog.Errorf("Failed while getting a Node to retry updating node health. Probably Node %s was deleted.", name)return false, err}return false, nil}); err != nil {klog.Errorf("Update health of Node "%v" from Controller error: %v. "+"Skipping - no pods will be evicted.", node.Name, err)continue}// Some nodes may be excluded from disruption checkingif !isNodeExcludedFromDisruptionChecks(node) {zoneToNodeConditions[utilnode.GetZoneKey(node)] = append(zoneToNodeConditions[utilnode.GetZoneKey(node)], currentReadyCondition)}if currentReadyCondition != nil {pods, err := nc.getPodsAssignedToNode(node.Name)if err != nil {utilruntime.HandleError(fmt.Errorf("unable to list pods of node %v: %v", node.Name, err))if currentReadyCondition.Status != v1.ConditionTrue && observedReadyCondition.Status == v1.ConditionTrue {// If error happened during node status transition (Ready -> NotReady)// we need to mark node for retry to force MarkPodsNotReady execution// in the next iteration.nc.nodesToRetry.Store(node.Name, struct{}{})}continue}if nc.useTaintBasedEvictions {nc.processTaintBaseEviction(node, &observedReadyCondition)} else {if err := nc.processNoTaintBaseEviction(node, &observedReadyCondition, gracePeriod, pods); err != nil {utilruntime.HandleError(fmt.Errorf("unable to evict all pods from node %v: %v; queuing for retry", node.Name, err))}}_, needsRetry := nc.nodesToRetry.Load(node.Name)switch {case currentReadyCondition.Status != v1.ConditionTrue && observedReadyCondition.Status == v1.ConditionTrue:// Report node event only once when status changed.nodeutil.RecordNodeStatusChange(nc.recorder, node, "NodeNotReady")fallthroughcase needsRetry && observedReadyCondition.Status != v1.ConditionTrue:if err = nodeutil.MarkPodsNotReady(nc.kubeClient, pods, node.Name); err != nil {utilruntime.HandleError(fmt.Errorf("unable to mark all pods NotReady on node %v: %v; queuing for retry", node.Name, err))nc.nodesToRetry.Store(node.Name, struct{}{})continue}}}nc.nodesToRetry.Delete(node.Name)}nc.handleDisruption(zoneToNodeConditions, nodes)return nil}

3.6.1 nc.tryUpdateNodeHealth

nc.tryUpdateNodeHealth方法主要是根据当前获取的node对象的ready condition值、node lease的更新时间等来更新nc.nodeHealthMap中的数据、更新node的condition值，并返回gracePeriod、上次记录的node的ready condition值observedReadyCondition、本次计算出来的node的ready condition值currentReadyCondition；

nc.tryUpdateNodeHealth方法主要逻辑为：（1）从node对象中获取ready condition的值，如果其为空，则设置observedReadyCondition为unknown并设置gracePeriod为nc.nodeStartupGracePeriod；否则设置gracePeriod值为nc.nodeMonitorGracePeriod，设置observedReadyCondition值为从node对象中获取到的ready condition的值；（2）nodeHealth的status、probeTimestamp、readyTransitionTimestamp属性值赋值相关逻辑处理，status赋值为node.status，probeTimestamp赋值为现在的时间，当ready condition的LastTransitionTime值有所变化，设置readyTransitionTimestamp值为现在的时间；（3）获取node对应的lease对象，判断其spec.RenewTime属性值是否比上次记录的时间（nodeHealth.lease.spec.RenewTime）要新，是则更新nodeHealth的lease为新lease对象、更新probeTimestamp为此时此刻的时间；（4）判断现在距离上次探测时间probeTimestamp是否已经超过了nc.nodeMonitorGracePeriod时间，是则将该node的ready condition、memoryPressure condition、diskPressure condition、pidPressure condition的值都更新为unknown，最后判断上一次记录的node的ready condition的值与本次的是否一致，不一致则更新nodeHealth的readyTransitionTimestamp的时间为现在；（5）最后返回gracePeriod、上次记录的node的ready condition值observedReadyCondition、本次计算出来的node的ready condition值currentReadyCondition；

3.6.2 nc.processTaintBaseEviction

nc.processTaintBaseEviction方法为污点驱逐的处理逻辑：（1）当node的ready condition属性值为false时去除Unrearchable的污点而添加Notready的污点，并将该node加入zoneNoExecuteTainter队列中；（2）为unknown时去除Notready的污点而添加Unrearchable的污点，并将该node加入zoneNoExecuteTainter队列中；（3）为true时去除Notready、Unrearchable的污点，然后将该node从zoneNoExecuteTainter队列中移除；

// pkg/controller/nodelifecycle/node_lifecycle_controller.gofunc (nc *Controller) processTaintBaseEviction(node *v1.Node, observedReadyCondition *v1.NodeCondition) {decisionTimestamp := nc.now()// Check eviction timeout against decisionTimestampswitch observedReadyCondition.Status {case v1.ConditionFalse:// We want to update the taint straight away if Node is already tainted with the UnreachableTaintif taintutils.TaintExists(node.Spec.Taints, UnreachableTaintTemplate) {taintToAdd := *NotReadyTaintTemplateif !nodeutil.SwapNodeControllerTaint(nc.kubeClient, []*v1.Taint{&taintToAdd}, []*v1.Taint{UnreachableTaintTemplate}, node) {klog.Errorf("Failed to instantly swap UnreachableTaint to NotReadyTaint. Will try again in the next cycle.")}} else if nc.markNodeForTainting(node) {klog.V(2).Infof("Node %v is NotReady as of %v. Adding it to the Taint queue.",node.Name,decisionTimestamp,)}case v1.ConditionUnknown:// We want to update the taint straight away if Node is already tainted with the UnreachableTaintif taintutils.TaintExists(node.Spec.Taints, NotReadyTaintTemplate) {taintToAdd := *UnreachableTaintTemplateif !nodeutil.SwapNodeControllerTaint(nc.kubeClient, []*v1.Taint{&taintToAdd}, []*v1.Taint{NotReadyTaintTemplate}, node) {klog.Errorf("Failed to instantly swap UnreachableTaint to NotReadyTaint. Will try again in the next cycle.")}} else if nc.markNodeForTainting(node) {klog.V(2).Infof("Node %v is unresponsive as of %v. Adding it to the Taint queue.",node.Name,decisionTimestamp,)}case v1.ConditionTrue:removed, err := nc.markNodeAsReachable(node)if err != nil {klog.Errorf("Failed to remove taints from node %v. Will retry in next iteration.", node.Name)}if removed {klog.V(2).Infof("Node %s is healthy again, removing all taints", node.Name)}}}

3.6.3 nc.processNoTaintBaseEviction

nc.processNoTaintBaseEviction方法为未开启污点驱逐时的驱逐处理逻辑：（1）当node的ready condition属性值为false时，判断距该node上一次的readyTransitionTimestamp时间是否超过了 podEvictionTimeout，是则将该node加入到zonePodEvictor队列中，最终该node上的pod会被驱逐；（2）当node的ready condition属性值为unknow时，判断距该node上一次的probeTimestamp时间是否超过了 podEvictionTimeout，是则将该node加入到zonePodEvictor队列中，最终该node上的pod会被驱逐；（3）当node的ready condition属性值为true时，调用nc.cancelPodEviction，将该node从zonePodEvictor队列中移除，代表不再对该node上的pod执行驱逐操作；

// pkg/controller/nodelifecycle/node_lifecycle_controller.gofunc (nc *Controller) processNoTaintBaseEviction(node *v1.Node, observedReadyCondition *v1.NodeCondition, gracePeriod time.Duration, pods []*v1.Pod) error {decisionTimestamp := nc.now()nodeHealthData := nc.nodeHealthMap.getDeepCopy(node.Name)if nodeHealthData == nil {return fmt.Errorf("health data doesn"t exist for node %q", node.Name)}// Check eviction timeout against decisionTimestampswitch observedReadyCondition.Status {case v1.ConditionFalse:if decisionTimestamp.After(nodeHealthData.readyTransitionTimestamp.Add(nc.podEvictionTimeout)) {enqueued, err := nc.evictPods(node, pods)if err != nil {return err}if enqueued {klog.V(2).Infof("Node is NotReady. Adding Pods on Node %s to eviction queue: %v is later than %v + %v",node.Name,decisionTimestamp,nodeHealthData.readyTransitionTimestamp,nc.podEvictionTimeout,)}}case v1.ConditionUnknown:if decisionTimestamp.After(nodeHealthData.probeTimestamp.Add(nc.podEvictionTimeout)) {enqueued, err := nc.evictPods(node, pods)if err != nil {return err}if enqueued {klog.V(2).Infof("Node is unresponsive. Adding Pods on Node %s to eviction queues: %v is later than %v + %v",node.Name,decisionTimestamp,nodeHealthData.readyTransitionTimestamp,nc.podEvictionTimeout-gracePeriod,)}}case v1.ConditionTrue:if nc.cancelPodEviction(node) {klog.V(2).Infof("Node %s is ready again, cancelled pod eviction", node.Name)}}return nil}

总结

NodeLifecycleController主要功能有：（1）定期检查node的心跳上报，某个node间隔一定时间都没有心跳上报时，更新node的ready condition值为false或unknown，开启了污点驱逐的情况下，给该node添加NoExecute的污点；（2）当污点驱逐未开启时，当node的ready Condition值为false或unknown且已经持续了一段时间（该时间可配置）时，对该node上的pod做驱逐（删除）操作；（3）当污点驱逐开启时，node上有NoExecute污点后，立马驱逐（删除）不能容忍污点的pod，对于能容忍该污点的pod，则等待所有污点的容忍时间里最小值后，pod才被驱逐（删除）；

驱逐中的zone概念

根据每个node对象的region和zone的label值，将node划分到不同的zone中；

region、zone值都相同的node，划分为同一个zone；

zone状态介绍

zone状态有四种，分别是：（1）Initial：初始化状态；（2）FullDisruption：ready的node数量为0，not ready的node数量大于0；（3）PartialDisruption：not ready的node数量大于2且其占比大于等于unhealthyZoneThreshold；（4）Normal：上述三种状态以外的情形，都属于该状态；

需要注意二级驱逐速率对驱逐的影响，即kcm启动参数--secondary-node-eviction-rate，代表如果某个zone下的unhealthy节点的百分比超过--unhealthy-zone-threshold （默认为 0.55）时，驱逐速率将会减小，如果不是LargeCluster（zone节点数量小于等于--large-cluster-size-threshold，默认为 50），驱逐操作将会停止，如果是LargeCluster，驱逐速率将降为每秒--secondary-node-eviction-rate 个，默认为0.01；