Kubernetes Node Controller源码分析之创建篇
Kubernetes Node Controller源码分析之创建篇
WaltonWang 发表于3个月前
Kubernetes Node Controller源码分析之创建篇
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摘要: 我认为,Node Controller是Kubernetes几十个Controller中最为重要的Controller之一,其重要程度在Top3,然而这可能也是最为复杂的一个Controller,因此对其的源码分析,我将做一个系列文章,希望能帮助自己有一个深入的理解。本博文主要对Node Controller的创建流程进行源码分析。

Author: xidianwangtao@gmail.com

NewNodeController入口

Controller Manager在启动时,会启动一系列的Controller,Node Controller也是在Controller Manager启动时StartControllers方法中启动的Controller之一,其对应的创建代码如下。

cmd/kube-controller-manager/app/controllermanager.go:455

nodeController, err := nodecontroller.NewNodeController(
			sharedInformers.Core().V1().Pods(),
			sharedInformers.Core().V1().Nodes(),
			sharedInformers.Extensions().V1beta1().DaemonSets(),
			cloud,
			clientBuilder.ClientOrDie("node-controller"),
			s.PodEvictionTimeout.Duration,
			s.NodeEvictionRate,
			s.SecondaryNodeEvictionRate,
			s.LargeClusterSizeThreshold,
			s.UnhealthyZoneThreshold,
			s.NodeMonitorGracePeriod.Duration,
			s.NodeStartupGracePeriod.Duration,
			s.NodeMonitorPeriod.Duration,
			clusterCIDR,
			serviceCIDR,
			int(s.NodeCIDRMaskSize),
			s.AllocateNodeCIDRs,
			s.EnableTaintManager,
			utilfeature.DefaultFeatureGate.Enabled(features.TaintBasedEvictions),
		)

可见,Node Controller主要是ListWatch sharedInformers中的如下对象:

  • Pods
  • Nodes
  • DaemonSets

另外,需要注意:

  • s.EnableTaintManager的默认值为true,即表示默认开启Taint Manager,可通过--enable-taint-manager进行设置。
  • DefaultFeatureGate.Enabled(features.TaintBasedEvictions)的默认值为false,可通过--feature-gates中添加TaintBasedEvictions=true修改为true,true即表示Node上的Pods Eviction Operation通过TaintManager来进行。

补充:关于Kubernetes的Default FeaturesGate的设置见如下代码:

pkg/features/kube_features.go:100

var defaultKubernetesFeatureGates = map[utilfeature.Feature]utilfeature.FeatureSpec{
	ExternalTrafficLocalOnly:                    {Default: true, PreRelease: utilfeature.Beta},
	AppArmor:                                    {Default: true, PreRelease: utilfeature.Beta},
	DynamicKubeletConfig:                        {Default: false, PreRelease: utilfeature.Alpha},
	DynamicVolumeProvisioning:                   {Default: true, PreRelease: utilfeature.Alpha},
	ExperimentalHostUserNamespaceDefaultingGate: {Default: false, PreRelease: utilfeature.Beta},
	ExperimentalCriticalPodAnnotation:           {Default: false, PreRelease: utilfeature.Alpha},
	AffinityInAnnotations:                       {Default: false, PreRelease: utilfeature.Alpha},
	Accelerators:                                {Default: false, PreRelease: utilfeature.Alpha},
	TaintBasedEvictions:                         {Default: false, PreRelease: utilfeature.Alpha},

	// inherited features from generic apiserver, relisted here to get a conflict if it is changed
	// unintentionally on either side:
	StreamingProxyRedirects: {Default: true, PreRelease: utilfeature.Beta},
}

NewNodeController定义


func NewNodeController(
	podInformer coreinformers.PodInformer,
	nodeInformer coreinformers.NodeInformer,
	daemonSetInformer extensionsinformers.DaemonSetInformer,
	cloud cloudprovider.Interface,
	kubeClient clientset.Interface,
	podEvictionTimeout time.Duration,
	evictionLimiterQPS float32,
	secondaryEvictionLimiterQPS float32,
	largeClusterThreshold int32,
	unhealthyZoneThreshold float32,
	nodeMonitorGracePeriod time.Duration,
	nodeStartupGracePeriod time.Duration,
	nodeMonitorPeriod time.Duration,
	clusterCIDR *net.IPNet,
	serviceCIDR *net.IPNet,
	nodeCIDRMaskSize int,
	allocateNodeCIDRs bool,
	runTaintManager bool,
	useTaintBasedEvictions bool) (*NodeController, error) {
		
	...
	
	nc := &NodeController{
		cloud:                           cloud,
		knownNodeSet:                    make(map[string]*v1.Node),
		kubeClient:                      kubeClient,
		recorder:                        recorder,
		podEvictionTimeout:              podEvictionTimeout,
		maximumGracePeriod:              5 * time.Minute,    // 不可配置,表示"The maximum duration before a pod evicted from a node can be forcefully terminated"
		zonePodEvictor:                  make(map[string]*RateLimitedTimedQueue),
		zoneNotReadyOrUnreachableTainer: make(map[string]*RateLimitedTimedQueue),
		nodeStatusMap:                   make(map[string]nodeStatusData),
		nodeMonitorGracePeriod:          nodeMonitorGracePeriod,
		nodeMonitorPeriod:               nodeMonitorPeriod,
		nodeStartupGracePeriod:          nodeStartupGracePeriod,
		lookupIP:                        net.LookupIP,
		now:                             metav1.Now,
		clusterCIDR:                     clusterCIDR,
		serviceCIDR:                     serviceCIDR,
		allocateNodeCIDRs:               allocateNodeCIDRs,
		forcefullyDeletePod:             func(p *v1.Pod) error { return forcefullyDeletePod(kubeClient, p) },
		nodeExistsInCloudProvider:       func(nodeName types.NodeName) (bool, error) { return nodeExistsInCloudProvider(cloud, nodeName) },
		evictionLimiterQPS:              evictionLimiterQPS,
		secondaryEvictionLimiterQPS:     secondaryEvictionLimiterQPS,
		largeClusterThreshold:           largeClusterThreshold,
		unhealthyZoneThreshold:          unhealthyZoneThreshold,
		zoneStates:                      make(map[string]zoneState),
		runTaintManager:                 runTaintManager,
		useTaintBasedEvictions:          useTaintBasedEvictions && runTaintManager,
	}
	
	...
	
	// 注册enterPartialDisruptionFunc函数为ReducedQPSFunc,当zone state为"PartialDisruption"时,将invoke ReducedQPSFunc来setLimiterInZone。
	nc.enterPartialDisruptionFunc = nc.ReducedQPSFunc
	
	// 注册enterFullDisruptionFunc函数为HealthyQPSFunc,当zone state为"FullDisruption"时,将invoke HealthyQPSFunc来setLimiterInZone。
	nc.enterFullDisruptionFunc = nc.HealthyQPSFunc
	
	// 注册computeZoneStateFunc函数为ComputeZoneState,当handleDisruption时,将invoke ComputeZoneState来计算集群中unhealthy node number及zone state。
	nc.computeZoneStateFunc = nc.ComputeZoneState
	
	
	// 注册PodInformer的Event Handler:Add,Update,Delete。
podInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{

        // 对于Pod Add和Update Event,都会去判断Node上kubelet的version,如果version低于1.1.0,则会通过forcefullyDeletePod直接调用apiserver接口删除etcd中该Pod object。
        // 对于Pod Add, Update, Delete Event,如果启动了TaintManager,则会对比OldPod和newPod的Tolerations信息,如果不相同,则会将该Pod的变更信息Add到NoExecuteTaintManager的podUpdateQueue中,交给Taint Controller处理。只不过对于Delete Event,newPod 为nil。
		AddFunc: func(obj interface{}) {
			nc.maybeDeleteTerminatingPod(obj)
			pod := obj.(*v1.Pod)
			if nc.taintManager != nil {
				nc.taintManager.PodUpdated(nil, pod)
			}
		},
		UpdateFunc: func(prev, obj interface{}) {
			nc.maybeDeleteTerminatingPod(obj)
			prevPod := prev.(*v1.Pod)
			newPod := obj.(*v1.Pod)
			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.Node here and we need to handle that correctly. #34692
			if !isPod {
				deletedState, ok := obj.(cache.DeletedFinalStateUnknown)
				if !ok {
					glog.Errorf("Received unexpected object: %v", obj)
					return
				}
				pod, ok = deletedState.Obj.(*v1.Pod)
				if !ok {
					glog.Errorf("DeletedFinalStateUnknown contained non-Node object: %v", deletedState.Obj)
					return
				}
			}
			if nc.taintManager != nil {
				nc.taintManager.PodUpdated(pod, nil)
			}
		},
	})
	
	// returns true if the shared informer's store has synced.
	nc.podInformerSynced = podInformer.Informer().HasSynced
	
	
	// 注册NodeInformer的Event Handler:Add,Update,Delete。
	nodeEventHandlerFuncs := cache.ResourceEventHandlerFuncs{}
	if nc.allocateNodeCIDRs {
	   // --allocate-node-cidrs —— Should CIDRs for Pods be allocated and set on the cloud provider。
		...
	} else {
		nodeEventHandlerFuncs = cache.ResourceEventHandlerFuncs{
		
		  // 对于Node Add, Update, Delete Event,如果启动了TaintManager,则会对比OldNode和newNode的Taints信息,如果不相同,则会将该Node的变更信息Add到NoExecuteTaintManager的nodeUpdateQueue中,交给Taint Controller处理。只不过对于Delete Event,newNode 为nil。
			AddFunc: func(originalObj interface{}) {
				obj, err := api.Scheme.DeepCopy(originalObj)
				if err != nil {
					utilruntime.HandleError(err)
					return
				}
				node := obj.(*v1.Node)
				if nc.taintManager != nil {
					nc.taintManager.NodeUpdated(nil, node)
				}
			},
			UpdateFunc: func(oldNode, newNode interface{}) {
				node := newNode.(*v1.Node)
				prevNode := oldNode.(*v1.Node)
				if nc.taintManager != nil {
					nc.taintManager.NodeUpdated(prevNode, node)

				}
			},
			DeleteFunc: func(originalObj interface{}) {
				obj, err := api.Scheme.DeepCopy(originalObj)
				if err != nil {
					utilruntime.HandleError(err)
					return
				}

				node, isNode := obj.(*v1.Node)
				// We can get DeletedFinalStateUnknown instead of *v1.Node here and we need to handle that correctly. #34692
				if !isNode {
					deletedState, ok := obj.(cache.DeletedFinalStateUnknown)
					if !ok {
						glog.Errorf("Received unexpected object: %v", obj)
						return
					}
					node, ok = deletedState.Obj.(*v1.Node)
					if !ok {
						glog.Errorf("DeletedFinalStateUnknown contained non-Node object: %v", deletedState.Obj)
						return
					}
				}
				if nc.taintManager != nil {
					nc.taintManager.NodeUpdated(node, nil)
				}
			},
		}
	}
	
	// 注册NoExecuteTaintManager为taintManager。
	if nc.runTaintManager {
		nc.taintManager = NewNoExecuteTaintManager(kubeClient)
	}
	nodeInformer.Informer().AddEventHandler(nodeEventHandlerFuncs)
	nc.nodeLister = nodeInformer.Lister()
	
	// returns true if the shared informer's nodeStore has synced.
	nc.nodeInformerSynced = nodeInformer.Informer().HasSynced
	
	// returns true if the shared informer's daemonSetStore has synced.
	nc.daemonSetStore = daemonSetInformer.Lister()
	nc.daemonSetInformerSynced = daemonSetInformer.Informer().HasSynced

	return nc, nil
	

因此,创建NodeController实例时,主要进行了如下工作:

  • maximumGracePeriod - The maximum duration before a pod evicted from a node can be forcefully terminated. 不可配置,代码中写死为5min。
  • 注册enterPartialDisruptionFunc函数为ReducedQPSFunc,当zone state为"PartialDisruption"时,将invoke ReducedQPSFuncsetLimiterInZone
  • 注册enterFullDisruptionFunc函数为HealthyQPSFunc,当zone state为"FullDisruption"时,将invoke HealthyQPSFuncsetLimiterInZone
  • 注册computeZoneStateFunc函数为ComputeZoneState,当handleDisruption时,将invoke ComputeZoneState来计算集群中unhealthy node number及zone state。
  • 注册**PodInformer**的Event Handler:Add,Update,Delete。
    • 对于Pod Add和Update Event,都会去判断Node上kubelet version,如果version低于***1.1.0***,则会通过forcefullyDeletePod直接调用apiserver接口删除etcd中该Pod object。
    • 对于Pod Add, Update, Delete Event,如果启动了TaintManager,则会对比OldPod和newPod的Tolerations信息,如果不相同,则会将该Pod的变更信息Add到NoExecuteTaintManager的**podUpdateQueue**中,交给Taint Controller处理。只不过对于Delete Event,newPod 为nil。
  • 注册PodInformerSynced,用来检查the shared informer's Podstore 是否已经synced.
  • 注册**NodeInformer**的Event Handler:Add,Update,Delete。
    • 对于Node Add, Update, Delete Event,如果启动了TaintManager,则会对比OldNode和newNode的Taints信息,如果不相同,则会将该Node的变更信息Add到NoExecuteTaintManagernodeUpdateQueue中,交给Taint Controller处理。只不过对于Delete Event,newNode 为nil。
  • 注册NoExecuteTaintManager为taintManager。
  • 注册NodeInformerSynced,用来检查the shared informer's NodeStore 是否已经synced.
  • 注册DaemonSetInformerSynced,用来检查the shared informer's DaemonSetStore 是否已经synced.

关于ZoneState

上面提到ZoneState,关于***ZoneState***是怎么来的,见如下代码:

pkg/api/v1/types.go:3277

const (
	// NodeReady means kubelet is healthy and ready to accept pods.
	NodeReady NodeConditionType = "Ready"
	// NodeOutOfDisk means the kubelet will not accept new pods due to insufficient free disk
	// space on the node.
	NodeOutOfDisk NodeConditionType = "OutOfDisk"
	// NodeMemoryPressure means the kubelet is under pressure due to insufficient available memory.
	NodeMemoryPressure NodeConditionType = "MemoryPressure"
	// NodeDiskPressure means the kubelet is under pressure due to insufficient available disk.
	NodeDiskPressure NodeConditionType = "DiskPressure"
	// NodeNetworkUnavailable means that network for the node is not correctly configured.
	NodeNetworkUnavailable NodeConditionType = "NetworkUnavailable"
	// NodeInodePressure means the kubelet is under pressure due to insufficient available inodes.
	NodeInodePressure NodeConditionType = "InodePressure"
)



pkg/controller/node/nodecontroller.go:1149

// This function is expected to get a slice of NodeReadyConditions for all Nodes in a given zone.
// The zone is considered:
// - fullyDisrupted if there're no Ready Nodes,
// - partiallyDisrupted if at least than nc.unhealthyZoneThreshold percent of Nodes are not Ready,
// - normal otherwise
func (nc *NodeController) ComputeZoneState(nodeReadyConditions []*v1.NodeCondition) (int, zoneState) {
	readyNodes := 0
	notReadyNodes := 0
	for i := range nodeReadyConditions {
		if nodeReadyConditions[i] != nil && nodeReadyConditions[i].Status == v1.ConditionTrue {
			readyNodes++
		} else {
			notReadyNodes++
		}
	}
	switch {
	case readyNodes == 0 && notReadyNodes > 0:
		return notReadyNodes, stateFullDisruption
	case notReadyNodes > 2 && float32(notReadyNodes)/float32(notReadyNodes+readyNodes) >= nc.unhealthyZoneThreshold:
		return notReadyNodes, statePartialDisruption
	default:
		return notReadyNodes, stateNormal
	}
}

zone state共分为如下三种类型:

  • FullDisruption:Ready状态的Nodes number为0,并且NotReady状态的Nodes number大于0。
  • PartialDisruption:NotReady状态的Nodes number大于2,并且notReadyNodes/(notReadyNodes+readyNodes) >= nc.unhealthyZoneThreshold,其中nc.unhealthyZoneThreshold通过--unhealthy-zone-threshold设置,默认为0.55。
  • Normal:除了以上两种zone state,其他都属于Normal状态。

关于Node Controller的其他博文:

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