本篇内容介绍了“Kubernetes Node Controller怎么启动”的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！
Node Controller的启动
if ctx.IsControllerEnabled(nodeControllerName) {
// 解析得到Cluster CIDR， # clusterCIDR is CIDR Range for Pods in cluster.
_, clusterCIDR, err := net.ParseCIDR(s.ClusterCIDR)
// 解析得到Service CIDR，# serviceCIDR is CIDR Range for Services in cluster.
_, serviceCIDR, err := net.ParseCIDR(s.ServiceCIDR)
// 创建NodeController实例
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),
)
// 执行Run方法启动该Controller
nodeController.Run()
// sleep一个随机时间，该时间大小为 “ControllerStartInterval + rand.Float64()*1.0*float64(ControllerStartInterval))”，其中ControllerStartInterval可以通过配置kube-controller-manager的"--controller-start-interval”参数指定。
time.Sleep(wait.Jitter(s.ControllerStartInterval.Duration, ControllerStartJitter))
}因此，很清晰地，关键就在以下两步：
nodeController, err := nodecontroller.NewNodeController创建NodeController实例。
nodeController.Run()执行Run方法启动该Controller。
NodeController的定义
在分析NodeController的原理之前，我们有必要先看看NodeController是如何定义的，其完整的定义如下：
type NodeController struct {
allocateNodeCIDRs bool
cloud cloudprovider.Interface
clusterCIDR *net.IPNet
serviceCIDR *net.IPNet
knownNodeSet map[string]*v1.Node
kubeClient clientset.Interface
// Method for easy mocking in unittest.
lookupIP func(host string) ([]net.IP, error)
// Value used if sync_nodes_status=False. NodeController will not proactively
// sync node status in this case, but will monitor node status updated from kubelet. If
// it doesn't receive update for this amount of time, it will start posting "NodeReady==
// ConditionUnknown". The amount of time before which NodeController start evicting pods
// is controlled via flag 'pod-eviction-timeout'.
// Note: be cautious when changing the constant, it must work with nodeStatusUpdateFrequency
// in kubelet. There are several constraints:
// 1. nodeMonitorGracePeriod must be N times more than nodeStatusUpdateFrequency, where
// N means number of retries allowed for kubelet to post node status. It is pointless
// to make nodeMonitorGracePeriod be less than nodeStatusUpdateFrequency, since there
// will only be fresh values from Kubelet at an interval of nodeStatusUpdateFrequency.
// 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 status.
nodeMonitorGracePeriod time.Duration
// Value controlling NodeController monitoring period, i.e. how often does NodeController
// check node status posted from kubelet. This value should be lower than nodeMonitorGracePeriod.
// TODO: Change node status monitor to watch based.
nodeMonitorPeriod time.Duration
// Value used if sync_nodes_status=False, only for node startup. When node
// is just created, e.g. cluster bootstrap or node creation, we give a longer grace period.
nodeStartupGracePeriod time.Duration
// per Node map storing last observed Status together with a local time when it was observed.
// This timestamp is to be used instead of LastProbeTime stored in Condition. We do this
// to aviod the problem with time skew across the cluster.
nodeStatusMap map[string]nodeStatusData
now func() metav1.Time
// Lock to access evictor workers
evictorLock sync.Mutex
// workers that evicts pods from unresponsive nodes.
zonePodEvictor map[string]*RateLimitedTimedQueue
// workers that are responsible for tainting nodes.
zoneNotReadyOrUnreachableTainer map[string]*RateLimitedTimedQueue
podEvictionTimeout time.Duration
// The maximum duration before a pod evicted from a node can be forcefully terminated.
maximumGracePeriod time.Duration
recorder record.EventRecorder
nodeLister corelisters.NodeLister
nodeInformerSynced cache.InformerSynced
daemonSetStore extensionslisters.DaemonSetLister
daemonSetInformerSynced cache.InformerSynced
podInformerSynced cache.InformerSynced
// allocate/recycle CIDRs for node if allocateNodeCIDRs == true
cidrAllocator CIDRAllocator
// manages taints
taintManager *NoExecuteTaintManager
forcefullyDeletePod func(*v1.Pod) error
nodeExistsInCloudProvider func(types.NodeName) (bool, error)
computeZoneStateFunc func(nodeConditions []*v1.NodeCondition) (int, zoneState)
enterPartialDisruptionFunc func(nodeNum int) float32
enterFullDisruptionFunc func(nodeNum int) float32
zoneStates map[string]zoneState
evictionLimiterQPS float32
secondaryEvictionLimiterQPS float32
largeClusterThreshold int32
unhealthyZoneThreshold float32
// if set to true NodeController will start TaintManager that will evict Pods from
// tainted nodes, if they're not tolerated.
runTaintManager bool
// if set to true NodeController will taint Nodes with 'TaintNodeNotReady' and 'TaintNodeUnreachable'
// taints instead of evicting Pods itself.
useTaintBasedEvictions bool
}NodeController的行为配置
整个NodeController结构体非常复杂，包含30+项，我们将重点关注：
clusterCIDR - 通过--cluster-cidr 来设置，表示CIDR Range for Pods in cluster。
serivceCIDR - 通过--service-cluster-ip-range来设置，表示CIDR Range for Services in cluster。
knownNodeSet - 用来记录NodeController observed节点的集合。
nodeMonitorGracePeriod - 通过--node-monitor-grace-period来设置，默认为40s，表示在标记某个Node为unhealthy前，允许40s内该Node unresponsive。
nodeMonitorPeriod - 通过--node-monitor-period 来设置，默认为5s，表示在NodeController中同步NodeStatus的周期。
nodeStatusMap - 用来记录每个Node最近一次观察到的Status。
zonePodEvictor - workers that evicts pods from unresponsive nodes.
zoneNotReadyOrUnreachableTainer - workers that are responsible for tainting nodes.
podEvictionTimeout - 通过--pod-eviction-timeout设置，默认为5min，表示在强制删除Pod时，允许的最大的Pod eviction时间。
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。
nodeLister - 用来获取Node数据的Interface。
daemonSetStore - 用来获取 daemonSet数据的Interface。在通过Eviction方式删除Pods时，会跳过该Node上所有的daemonSet对应的Pods。
taintManager - 它是一个NoExecuteTaintManager对象，当runTaintManager(默认true)为true时:
PodInformer和NodeInformer将监听到PodAdd,PodDelete,PodUpdate和NodeAdd,NodeDelete,NodeUpdate事件后，
触发TraintManager执行对应的NoExecuteTaintManager.PodUpdated和NoExecuteTaintManager.NodeUpdated方法，
将事件加入到对应的queue(podUpdateQueue and nodeUpdateQueue)，TaintController会从这些queue中消费这些消息，
TaintController分别调用handlePodUpdate和handleNodeUpdate处理。
具体的TaintController的处理逻辑，后续再单独分析。
forcefullyDeletePod - 该方法用来NodeController调用apiserver接口强制删除该Pod。用来删除那些被调度到kubelet version 小于v1.1.0 Node上的Pod，因为kubelet v1.1.0之前的版本不支持graceful termination。
computeZoneStateFunc - 该方法返回Zone中NotReadyNodes数量以及该Zone的state。
如果没有一个Ready Node，则该node state为FullDisruption；
如果unhealthy Nodes所占的比例大于等于unhealthyZoneThreshold,则该node state为PartialDisruption;
否则该node state就是Narmal。
enterPartialDisruptionFunc - 该方法用当前node num对比largeClusterThreshold ：
enterFullDisruptionFunc - 用来获取evictionLimiterQPS（默认为0.1）的方法，关于evictionLimiterQPS 的理解见下。
zoneStates - 表示各个zone的状态，状态值可以为
Initial;
Normal;
FullDisruption;
PartialDisruption;
evictionLimiterQPS - 通过--node-eviction-rate设置，默认为0.1，表示当某个Zone status为healthy时，每秒应该剔除的Nodes数量，即每10s剔除1个Node。
secondaryEvictionLimiterQPS - 通过--secondary-node-eviction-rate设置，默认为0.01，表示当某个Zone status为unhealthy时，每秒应该剔除的Nodes数量，即每100s剔除1个Node。
largeClusterThreshold - 通过--large-cluster-size-threshold设置，默认为50，表示当健康nodes组成的集群规模小于等于50时，secondary-node-eviction-rate将被设置为0。
unhealthyZoneThreshold - 通过--unhealthy-zone-threshold设置，默认为0.55，表示当某个Zone中unhealthy Nodes（最少为3）所占的比例达到0.55时，就认为该Zone的状态为unhealthy。
runTaintManager - 在--enable-taint-manager中指定，默认为true。如果为true，则表示NodeController将会启动TaintManager，由TaintManager负责将不能容忍该Taint的Nodes上的Pods进行evict操作。
useTaintBasedEvictions - 在--feature-gates中指定，默认TaintBasedEvictions=false,仍属于Alpha特性。如果为true，则表示将通过Taint Nodes的方式来Evict Pods。
“Kubernetes Node Controller怎么启动”的内容就介绍到这里了，感谢大家的阅读。如果想了解更多行业相关的知识可以关注天达云网站，小编将为大家输出更多高质量的实用文章！