溫馨提示×
您好，登錄后才能下訂單哦！
點擊 登錄注冊 即表示同意《億速云用戶服務條款》
您好，登錄后才能下訂單哦！
本篇內容介紹了“Kubernetes StatefulSet源碼是什么”的有關知識，在實際案例的操作過程中，不少人都會遇到這樣的困境，接下來就讓小編帶領大家學習一下如何處理這些情況吧！希望大家仔細閱讀，能夠學有所成！
下面是簡單的StatefulSet Controller工作的內部結構圖。 
同其他Controller一樣，StatefulSet Controller也是由ControllerManager初始化時負責啟動。
// NewStatefulSetController creates a new statefulset controller.
func NewStatefulSetController(
podInformer coreinformers.PodInformer,
setInformer appsinformers.StatefulSetInformer,
pvcInformer coreinformers.PersistentVolumeClaimInformer,
revInformer appsinformers.ControllerRevisionInformer,
kubeClient clientset.Interface,
) *StatefulSetController {
...
ssc := &StatefulSetController{
kubeClient: kubeClient,
control: NewDefaultStatefulSetControl(
NewRealStatefulPodControl(
kubeClient,
setInformer.Lister(),
podInformer.Lister(),
pvcInformer.Lister(),
recorder),
NewRealStatefulSetStatusUpdater(kubeClient, setInformer.Lister()),
history.NewHistory(kubeClient, revInformer.Lister()),
),
pvcListerSynced: pvcInformer.Informer().HasSynced,
queue: workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), "statefulset"),
podControl: controller.RealPodControl{KubeClient: kubeClient, Recorder: recorder},
revListerSynced: revInformer.Informer().HasSynced,
}
podInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
// lookup the statefulset and enqueue
AddFunc: ssc.addPod,
// lookup current and old statefulset if labels changed
UpdateFunc: ssc.updatePod,
// lookup statefulset accounting for deletion tombstones
DeleteFunc: ssc.deletePod,
})
ssc.podLister = podInformer.Lister()
ssc.podListerSynced = podInformer.Informer().HasSynced
setInformer.Informer().AddEventHandlerWithResyncPeriod(
cache.ResourceEventHandlerFuncs{
AddFunc: ssc.enqueueStatefulSet,
UpdateFunc: func(old, cur interface{}) {
oldPS := old.(*apps.StatefulSet)
curPS := cur.(*apps.StatefulSet)
if oldPS.Status.Replicas != curPS.Status.Replicas {
glog.V(4).Infof("Observed updated replica count for StatefulSet: %v, %d->%d", curPS.Name, oldPS.Status.Replicas, curPS.Status.Replicas)
}
ssc.enqueueStatefulSet(cur)
},
DeleteFunc: ssc.enqueueStatefulSet,
},
statefulSetResyncPeriod,
)
ssc.setLister = setInformer.Lister()
ssc.setListerSynced = setInformer.Informer().HasSynced
// TODO: Watch volumes
return ssc
}很熟悉的代碼風格，也是創建對應的eventBroadcaster，然后給對應的objectInformer注冊對應的eventHandler：
StatefulSetController主要ListWatch Pod和StatefulSet對象；
Pod Informer注冊了add/update/delete EventHandler，這三個EventHandler都會將Pod對應的StatefulSet加入到StatefulSet Queue中。
StatefulSet Informer同樣注冊了add/update/event EventHandler，也都會將StatefulSet加入到StatefulSet Queue中。
目前StatefulSetController還未感知PVC Informer的EventHandler，這里繼續按照PVC Controller全部處理。在StatefulSet Controller創建和刪除Pod時，會調用apiserver創建和刪除對應的PVC。
RevisionController類似，在StatefulSet Controller Reconcile時會創建或者刪除對應的Revision。
接下來，會進入StatefulSetController的worker（只有一個worker，也就是只一個go routine），worker會從StatefulSet Queue中pop out一個StatefulSet對象，然后執行sync進行Reconcile操作。
// sync syncs the given statefulset.
func (ssc *StatefulSetController) sync(key string) error {
startTime := time.Now()
defer func() {
glog.V(4).Infof("Finished syncing statefulset %q (%v)", key, time.Now().Sub(startTime))
}()
namespace, name, err := cache.SplitMetaNamespaceKey(key)
if err != nil {
return err
}
set, err := ssc.setLister.StatefulSets(namespace).Get(name)
if errors.IsNotFound(err) {
glog.Infof("StatefulSet has been deleted %v", key)
return nil
}
if err != nil {
utilruntime.HandleError(fmt.Errorf("unable to retrieve StatefulSet %v from store: %v", key, err))
return err
}
selector, err := metav1.LabelSelectorAsSelector(set.Spec.Selector)
if err != nil {
utilruntime.HandleError(fmt.Errorf("error converting StatefulSet %v selector: %v", key, err))
// This is a non-transient error, so don't retry.
return nil
}
if err := ssc.adoptOrphanRevisions(set); err != nil {
return err
}
pods, err := ssc.getPodsForStatefulSet(set, selector)
if err != nil {
return err
}
return ssc.syncStatefulSet(set, pods)
}sync中根據setLabel匹配出所有revisions、然后檢查這些revisions中是否有OwnerReference為空的，如果有，那說明存在Orphaned的Revisions。
注意：只要檢查到有一個History Revision就會觸發給所有的Resivions打上Patch：
{"metadata":{"ownerReferences":[{"apiVersion":"%s","kind":"%s","name":"%s","uid":"%s","controller":true,"blockOwnerDeletion":true}],"uid":"%s"}}
調用getPodsForStatefulSet獲取這個StatefulSet應該管理的Pods。
獲取該StatefulSet對應Namesapce下所有的Pods；
執行ClaimPods操作：檢查set和pod的Label是否匹配上，如果Label不匹配，那么需要release這個Pod，然后檢查pod的name和StatefulSet name的格式是否能匹配上。對于都匹配上的，并且ControllerRef UID也相同的，則不需要處理。
如果Selector和ControllerRef都匹配不上，則執行ReleasePod操作，給Pod打Patch: {“metadata":{"ownerReferences":[{"$patch":"delete","uid":"%s"}],"uid":"%s"}}
對于Label和name格式能匹配上的，但是controllerRef為空的Pods,就執行AdoptPod，給Pod打上Patch： {“metadata":{"ownerReferences":[{"apiVersion":"%s","kind":"%s","name":"%s","uid":"%s","controller":true,"blockOwnerDeletion":true}],"uid":"%s"}}
syncStatefulSet的實現只是調用UpdateStatefulSet。
func (ssc *defaultStatefulSetControl) UpdateStatefulSet(set *apps.StatefulSet, pods []*v1.Pod) error {
// list all revisions and sort them
revisions, err := ssc.ListRevisions(set)
if err != nil {
return err
}
history.SortControllerRevisions(revisions)
// get the current, and update revisions
currentRevision, updateRevision, collisionCount, err := ssc.getStatefulSetRevisions(set, revisions)
if err != nil {
return err
}
// perform the main update function and get the status
status, err := ssc.updateStatefulSet(set, currentRevision, updateRevision, collisionCount, pods)
if err != nil {
return err
}
// update the set's status
err = ssc.updateStatefulSetStatus(set, status)
if err != nil {
return err
}
glog.V(4).Infof("StatefulSet %s/%s pod status replicas=%d ready=%d current=%d updated=%d",
set.Namespace,
set.Name,
status.Replicas,
status.ReadyReplicas,
status.CurrentReplicas,
status.UpdatedReplicas)
glog.V(4).Infof("StatefulSet %s/%s revisions current=%s update=%s",
set.Namespace,
set.Name,
status.CurrentRevision,
status.UpdateRevision)
// maintain the set's revision history limit
return ssc.truncateHistory(set, pods, revisions, currentRevision, updateRevision)
}UpdateStatefulSet主要流程為：
ListRevisions獲取該StatefulSet的所有Revisions，并按照Revision從小到大進行排序。
getStatefulSetRevisions獲取currentRevison和UpdateRevision。
只有當RollingUpdate策略時Partition不為0時，才會有部分Pods是updateRevision。
其他情況，所有Pods都得維持currentRevision。
updateStatefulSet是StatefulSet Controller的核心邏輯，負責創建、更新、刪除Pods，使得聲明式target得以維護：
使得target state始終有Spec.Replicas個Running And Ready的Pods。
如果更新策略是RollingUpdate，并且Partition為0，則保證所有Pods都對應Status.CurrentRevision。
如果更新策略是RollingUpdate，并且Partition不為0，則ordinal小于Partition的Pods保持Status.CurrentRevision，而ordinal大于等于Partition的Pods更新到Status.UpdateRevision。
如果更新策略是OnDelete，則只有刪除Pods時才會觸發對應Pods的更新，也就是說與Revisions不關聯。
truncateHistory維護History Revision個數不超過.Spec.RevisionHistoryLimit。
updateStatefulSet是整個StatefulSetController的核心。
func (ssc *defaultStatefulSetControl) updateStatefulSet(
set *apps.StatefulSet,
currentRevision *apps.ControllerRevision,
updateRevision *apps.ControllerRevision,
collisionCount int32,
pods []*v1.Pod) (*apps.StatefulSetStatus, error) {
// get the current and update revisions of the set.
currentSet, err := ApplyRevision(set, currentRevision)
if err != nil {
return nil, err
}
updateSet, err := ApplyRevision(set, updateRevision)
if err != nil {
return nil, err
}
// set the generation, and revisions in the returned status
status := apps.StatefulSetStatus{}
status.ObservedGeneration = new(int64)
*status.ObservedGeneration = set.Generation
status.CurrentRevision = currentRevision.Name
status.UpdateRevision = updateRevision.Name
status.CollisionCount = new(int32)
*status.CollisionCount = collisionCount
replicaCount := int(*set.Spec.Replicas)
// slice that will contain all Pods such that 0 <= getOrdinal(pod) < set.Spec.Replicas
replicas := make([]*v1.Pod, replicaCount)
// slice that will contain all Pods such that set.Spec.Replicas <= getOrdinal(pod)
condemned := make([]*v1.Pod, 0, len(pods))
unhealthy := 0
firstUnhealthyOrdinal := math.MaxInt32
var firstUnhealthyPod *v1.Pod
// First we partition pods into two lists valid replicas and condemned Pods
for i := range pods {
status.Replicas++
// count the number of running and ready replicas
if isRunningAndReady(pods[i]) {
status.ReadyReplicas++
}
// count the number of current and update replicas
if isCreated(pods[i]) && !isTerminating(pods[i]) {
if getPodRevision(pods[i]) == currentRevision.Name {
status.CurrentReplicas++
} else if getPodRevision(pods[i]) == updateRevision.Name {
status.UpdatedReplicas++
}
}
if ord := getOrdinal(pods[i]); 0 <= ord && ord < replicaCount {
// if the ordinal of the pod is within the range of the current number of replicas,
// insert it at the indirection of its ordinal
replicas[ord] = pods[i]
} else if ord >= replicaCount {
// if the ordinal is greater than the number of replicas add it to the condemned list
condemned = append(condemned, pods[i])
}
// If the ordinal could not be parsed (ord < 0), ignore the Pod.
}
// for any empty indices in the sequence [0,set.Spec.Replicas) create a new Pod at the correct revision
for ord := 0; ord < replicaCount; ord++ {
if replicas[ord] == nil {
replicas[ord] = newVersionedStatefulSetPod(
currentSet,
updateSet,
currentRevision.Name,
updateRevision.Name, ord)
}
}
// sort the condemned Pods by their ordinals
sort.Sort(ascendingOrdinal(condemned))
// find the first unhealthy Pod
for i := range replicas {
if !isHealthy(replicas[i]) {
unhealthy++
if ord := getOrdinal(replicas[i]); ord < firstUnhealthyOrdinal {
firstUnhealthyOrdinal = ord
firstUnhealthyPod = replicas[i]
}
}
}
for i := range condemned {
if !isHealthy(condemned[i]) {
unhealthy++
if ord := getOrdinal(condemned[i]); ord < firstUnhealthyOrdinal {
firstUnhealthyOrdinal = ord
firstUnhealthyPod = condemned[i]
}
}
}
if unhealthy > 0 {
glog.V(4).Infof("StatefulSet %s/%s has %d unhealthy Pods starting with %s",
set.Namespace,
set.Name,
unhealthy,
firstUnhealthyPod.Name)
}
// If the StatefulSet is being deleted, don't do anything other than updating
// status.
if set.DeletionTimestamp != nil {
return &status, nil
}
monotonic := !allowsBurst(set)
// Examine each replica with respect to its ordinal
for i := range replicas {
// delete and recreate failed pods
if isFailed(replicas[i]) {
glog.V(4).Infof("StatefulSet %s/%s is recreating failed Pod %s",
set.Namespace,
set.Name,
replicas[i].Name)
if err := ssc.podControl.DeleteStatefulPod(set, replicas[i]); err != nil {
return &status, err
}
if getPodRevision(replicas[i]) == currentRevision.Name {
status.CurrentReplicas--
} else if getPodRevision(replicas[i]) == updateRevision.Name {
status.UpdatedReplicas--
}
status.Replicas--
replicas[i] = newVersionedStatefulSetPod(
currentSet,
updateSet,
currentRevision.Name,
updateRevision.Name,
i)
}
// If we find a Pod that has not been created we create the Pod
if !isCreated(replicas[i]) {
if err := ssc.podControl.CreateStatefulPod(set, replicas[i]); err != nil {
return &status, err
}
status.Replicas++
if getPodRevision(replicas[i]) == currentRevision.Name {
status.CurrentReplicas++
} else if getPodRevision(replicas[i]) == updateRevision.Name {
status.UpdatedReplicas++
}
// if the set does not allow bursting, return immediately
if monotonic {
return &status, nil
}
// pod created, no more work possible for this round
continue
}
// If we find a Pod that is currently terminating, we must wait until graceful deletion
// completes before we continue to make progress.
if isTerminating(replicas[i]) && monotonic {
glog.V(4).Infof(
"StatefulSet %s/%s is waiting for Pod %s to Terminate",
set.Namespace,
set.Name,
replicas[i].Name)
return &status, nil
}
// If we have a Pod that has been created but is not running and ready we can not make progress.
// We must ensure that all for each Pod, when we create it, all of its predecessors, with respect to its
// ordinal, are Running and Ready.
if !isRunningAndReady(replicas[i]) && monotonic {
glog.V(4).Infof(
"StatefulSet %s/%s is waiting for Pod %s to be Running and Ready",
set.Namespace,
set.Name,
replicas[i].Name)
return &status, nil
}
// Enforce the StatefulSet invariants
if identityMatches(set, replicas[i]) && storageMatches(set, replicas[i]) {
continue
}
// Make a deep copy so we don't mutate the shared cache
replica := replicas[i].DeepCopy()
if err := ssc.podControl.UpdateStatefulPod(updateSet, replica); err != nil {
return &status, err
}
}
// At this point, all of the current Replicas are Running and Ready, we can consider termination.
// We will wait for all predecessors to be Running and Ready prior to attempting a deletion.
// We will terminate Pods in a monotonically decreasing order over [len(pods),set.Spec.Replicas).
// Note that we do not resurrect Pods in this interval. Also not that scaling will take precedence over
// updates.
for target := len(condemned) - 1; target >= 0; target-- {
// wait for terminating pods to expire
if isTerminating(condemned[target]) {
glog.V(4).Infof(
"StatefulSet %s/%s is waiting for Pod %s to Terminate prior to scale down",
set.Namespace,
set.Name,
condemned[target].Name)
// block if we are in monotonic mode
if monotonic {
return &status, nil
}
continue
}
// if we are in monotonic mode and the condemned target is not the first unhealthy Pod block
if !isRunningAndReady(condemned[target]) && monotonic && condemned[target] != firstUnhealthyPod {
glog.V(4).Infof(
"StatefulSet %s/%s is waiting for Pod %s to be Running and Ready prior to scale down",
set.Namespace,
set.Name,
firstUnhealthyPod.Name)
return &status, nil
}
glog.V(4).Infof("StatefulSet %s/%s terminating Pod %s for scale dowm",
set.Namespace,
set.Name,
condemned[target].Name)
if err := ssc.podControl.DeleteStatefulPod(set, condemned[target]); err != nil {
return &status, err
}
if getPodRevision(condemned[target]) == currentRevision.Name {
status.CurrentReplicas--
} else if getPodRevision(condemned[target]) == updateRevision.Name {
status.UpdatedReplicas--
}
if monotonic {
return &status, nil
}
}
// for the OnDelete strategy we short circuit. Pods will be updated when they are manually deleted.
if set.Spec.UpdateStrategy.Type == apps.OnDeleteStatefulSetStrategyType {
return &status, nil
}
// we compute the minimum ordinal of the target sequence for a destructive update based on the strategy.
updateMin := 0
if set.Spec.UpdateStrategy.RollingUpdate != nil {
updateMin = int(*set.Spec.UpdateStrategy.RollingUpdate.Partition)
}
// we terminate the Pod with the largest ordinal that does not match the update revision.
for target := len(replicas) - 1; target >= updateMin; target-- {
// delete the Pod if it is not already terminating and does not match the update revision.
if getPodRevision(replicas[target]) != updateRevision.Name && !isTerminating(replicas[target]) {
glog.V(4).Infof("StatefulSet %s/%s terminating Pod %s for update",
set.Namespace,
set.Name,
replicas[target].Name)
err := ssc.podControl.DeleteStatefulPod(set, replicas[target])
status.CurrentReplicas--
return &status, err
}
// wait for unhealthy Pods on update
if !isHealthy(replicas[target]) {
glog.V(4).Infof(
"StatefulSet %s/%s is waiting for Pod %s to update",
set.Namespace,
set.Name,
replicas[target].Name)
return &status, nil
}
}
return &status, nil
}主要流程：
獲取currentRevision和updateRevision對應的StatefulSet Object，并設置generation，currentRevision, updateRevision等信息到StatefulSet status。
將前面getPodsForStatefulSet獲取到的pods分成兩個slice：
valid replicas slice: : 0 <= getOrdinal(pod) < set.Spec.Replicas
condemned pods slice: set.Spec.Replicas <= getOrdinal(pod)
如果valid replicas中存在某些ordinal沒有對應的Pod，則創建對應Revision的Pods Object，后面會檢測到該Pod沒有真實創建就會去創建對應的Pod實例：
如果更新策略是RollingUpdate且Partition為0或者ordinal < Partition，則使用currentRevision創建該Pod Object。
如果更新策略時RollingUpdate且Partition不為0且ordinal >= Partition，則使用updateRevision創建該Pod Object。
從valid repilcas和condemned pods兩個slices中找出第一個unhealthy的Pod。（ordinal最小的unhealth pod）
healthy pods means：pods is running and ready, and not terminating.
對于正在刪除(DeletionTimestamp非空)的StatefulSet，不做任何操作，直接返回當前status。
遍歷valid replicas中pods，保證valid replicas中index在[0，spec.replicas）的pod都是Running And Ready的：
Pod is Running and Ready means:
pod.Status.Phase = Runnin,
pod.Status.Condition = Ready
如果檢測到某個pod Failed (pod.Status.Phase = Failed), 則刪除這個Pod，并重新new這個pod object（注意revisions匹配）
如果這個pod還沒有recreate,則Create it。
如果ParallelPodManagement = "OrderedReady”，則直接返回當前status。否則ParallelPodManagement = "Parallel”,則循環檢測下一個。
如果pod正在刪除并且ParallelPodManagement = "OrderedReady”，則返回status結束。
如果pod不是RunningAndReady狀態，并且ParallelPodManagement = "OrderedReady”，則返回status結束。
檢測該pod與statefulset的identity和storage是否匹配，如果有一個不匹配，則調用apiserver Update Stateful Pod進行updateIdentity和updateStorage（并創建對應的PVC），返回status，結束。
遍歷condemned replicas中pods，index由大到小的順序，確保這些pods最終都被刪除：
如果這個Pod正在刪除(DeletionTimestamp)，并且Pod Management是OrderedReady，則進行Block住，返回status，流程結束。
如果是OrderedReady策略，Pod不是處于Running and Ready狀態，且該pod不是first unhealthy pod，則返回status，流程結束。
其他情況，則刪除該statefulset pod。
根據該pod的controller-revision-hash Label獲取Revision，如果等于currentRevision，則更新status.CurrentReplicas；如果等于updateRevision，則更新status.UpdatedReplicas；
如果是OrderedReady策略，則返回status，流程結束。
OnDelete更新策略：刪除Pod才會觸發更新這個ordinal的更新 如果UpdateStrategy Type是OnDelete, 意味著只有當對應的Pods被手動刪除后，才會觸發Recreate，因此直接返回status，流程結束。
RollingUpdate更新策略：（Partition不設置就相當于0，意味著全部pods進行滾動更新） 如果UpdateStrategy Type是RollingUpdate, 根據RollingUpdate中Partition配置得到updateMin作為update replicas index區間最小值，遍歷valid replicas，index從最大值到updateMin遞減的順序：
如果pod revision不是updateRevision，并且不是正在刪除的，則刪除這個pod，并更新status.CurrentReplicas，然后返回status，流程結束。
如果pod不是healthy的，那么將等待它變成healthy，因此這里就直接返回status，流程結束。
updateStatefulSet Reconcile中，會檢查identity match的情況，具體包含哪些？
StatefulSetPodNameLabel = "statefulset.kubernetes.io/pod-name"
// identityMatches returns true if pod has a valid identity and network identity for a member of set.
func identityMatches(set *apps.StatefulSet, pod *v1.Pod) bool {
parent, ordinal := getParentNameAndOrdinal(pod)
return ordinal >= 0 &&
set.Name == parent &&
pod.Name == getPodName(set, ordinal) &&
pod.Namespace == set.Namespace &&
pod.Labels[apps.StatefulSetPodNameLabel] == pod.Name
}pod name和statefulset name內容匹配。
namespace匹配。
Pod的Label：statefulset.kubernetes.io/pod-name與Pod name真實匹配。
updateStatefulSet Reconcile中，會檢查Storage match的情況，具體怎么匹配的呢？
// storageMatches returns true if pod's Volumes cover the set of PersistentVolumeClaims
func storageMatches(set *apps.StatefulSet, pod *v1.Pod) bool {
ordinal := getOrdinal(pod)
if ordinal < 0 {
return false
}
volumes := make(map[string]v1.Volume, len(pod.Spec.Volumes))
for _, volume := range pod.Spec.Volumes {
volumes[volume.Name] = volume
}
for _, claim := range set.Spec.VolumeClaimTemplates {
volume, found := volumes[claim.Name]
if !found ||
volume.VolumeSource.PersistentVolumeClaim == nil ||
volume.VolumeSource.PersistentVolumeClaim.ClaimName !=
getPersistentVolumeClaimName(set, &claim, ordinal) {
return false
}
}
return true
}基于上述分析，下面是一個相對完整的StatefulSetController的代碼邏輯圖。 (不支持大于2MB的圖片，所以不太清晰，不過基本在前面內容都提到了。)
在上一篇博文淺析Kubernetes StatefulSet中遺留了一個問題：StatefulSet滾動更新時，如果某個Pod更新失敗，會怎么辦呢？
通過上面源碼分析中滾動更新部分的分析，我們知道：
如果UpdateStrategy Type是RollingUpdate, 根據RollingUpdate中Partition（Partition不設置就相當于0，意味著全部pods進行滾動更新）配置得到updateMin作為update replicas index區間最小值，遍歷valid replicas，index從最大值到updateMin遞減的順序：
如果pod revision不是updateRevision，并且不是正在刪除的，則刪除這個pod，并更新status.CurrentReplicas，然后返回status，流程結束。
如果pod不是healthy的，那么將等待它變成healthy，因此這里就直接返回status，流程結束。
知道這一點后，就能回答這個問題了，答案很簡單：
如果更新策略是RollingUpdate，則逐個滾動更新過程中，如果在更新某個ordinal replica時這個Pod一直無法達到Running and Ready狀態，那么整個滾動更新流程將Block在這里。還沒有更新的replicas將不會觸發更新，已經更新成功的replicas就保持更新后的版本，并不存在什么自動回滾的機制。在下一次sync時，檢測到這個Pod isFailed（pod.Status.Phase = Failed）,會delete and recreate這個failed pod。
問題：podManagementPolicy: "Parallel"體現在什么時候呢？Scale的時候？RollingUpdate的時候？
在前面代碼分析中updateStatefulSet中那段-"遍歷valid replicas中pods，保證valid replicas中index在[0，spec.replicas）的pod都是Running And Ready的"：如果發現某個ordinal replica應該創建但是還沒被創建，則會觸發create。如果podManagementPolicy設置為Parallel，則會繼續delete then create其他應該創建的replicas，而不會等待前面創建的replicas成為Running and Ready。
在前面代碼分析中updateStatefulSet中那段-”遍歷condemned replicas中pods，index由大到小的順序，確保這些pods最終都被刪除"：podManagementPolicy設置為Parallel，如果發現某個ordinal replica正在刪除，則繼續刪除其他應該刪除的replicas，而不會等待之前刪除的replica重建并成為Running and Ready狀態。
因此Parallel體現在以下場景：
初始化部署StatefulSet時，并行create pods。
級聯刪除StatefulSet時，并行delete pods。
Scale up時，并行create pods。
Scale down時，并行delete pods。
而在滾動更新時，是不會受podManagementPolicy的配置影響的，都是按照逐個地、ordinal從大到小的的順序，保證前者Running and Ready的原則，進行RollingUpdate。
“Kubernetes StatefulSet源碼是什么”的內容就介紹到這里了，感謝大家的閱讀。如果想了解更多行業相關的知識可以關注億速云網站，小編將為大家輸出更多高質量的實用文章！
免責聲明：本站發布的內容（圖片、視頻和文字）以原創、轉載和分享為主，文章觀點不代表本網站立場，如果涉及侵權請聯系站長郵箱：is@yisu.com進行舉報，并提供相關證據，一經查實，將立刻刪除涉嫌侵權內容。
