作者 | 牧琦
來源 | 阿裡技術公衆号
基于 kubernetes 1.23
一 簡介
pv controller是 kcm 的元件之一，它負責處理叢集中的pvc/pv對象，對pvc/pv 對象進行狀态轉換。
二 pvController 初始化
初始化代碼在 pkg/controller/volume/persistentvolume/pv_controller_base.go 檔案中，NewController 主要做了如下幾件事情
- 初始化 eventRecorder
- 初始化 PersistentVolumeController 對象，
- 調用 VolumePluginMgr.InitPlugins() 方法 初始化存儲插件，代碼存在于 pkg/volume/plugins.go 檔案中
- 開始建立 informer 監聽叢集内的資源，初始化了如下 informer
- PersistentVolumeInformer
- PersistentVolumeClaimInformer
- StorageClassInformer
- PodInformer
- NodeInformer
- 将 PV & PVC 的 event 分别放入 volumeQueue & claimQueue
- 為了不每次都疊代 pods ，自定義一個通過 pvc 鍵索引 pod 的索引器
- 初始化 intree 存儲 -> csi 遷移相關功能的 manager
NewController代碼在cmd/kube-controller-manager代碼裡面被調用，初始化成功之後緊接着調用go Run()方法運作 pvController
三 開始運作
// 開始運作 pvController
func (ctrl *PersistentVolumeController) Run(stopCh <-chan struct{}) {
defer utilruntime.HandleCrash()
defer ctrl.claimQueue.ShutDown()
defer ctrl.volumeQueue.ShutDown()
klog.Infof("Starting persistent volume controller")
defer klog.Infof("Shutting down persistent volume controller")
if !cache.WaitForNamedCacheSync("persistent volume", stopCh, ctrl.volumeListerSynced, ctrl.claimListerSynced, ctrl.classListerSynced, ctrl.podListerSynced, ctrl.NodeListerSynced) {
return
}
ctrl.initializeCaches(ctrl.volumeLister, ctrl.claimLister)
go wait.Until(ctrl.resync, ctrl.resyncPeriod, stopCh)
go wait.Until(ctrl.volumeWorker, time.Second, stopCh)
go wait.Until(ctrl.claimWorker, time.Second, stopCh)
metrics.Register(ctrl.volumes.store, ctrl.claims, &ctrl.volumePluginMgr)
<-stopCh
} 同步緩存之後開始周期性執行 ctrl.resync,ctrl.volumeWorker , ctrl.claimWorker , 我們看下 initalizeCaches 方法
func (ctrl *PersistentVolumeController) initializeCaches(volumeLister corelisters.PersistentVolumeLister, claimLister corelisters.PersistentVolumeClaimLister) {
// 這裡不通路 apiserver，是從本地緩存拿出的對象，這些對象不可以被外部函數修改
volumeList, err := volumeLister.List(labels.Everything())
if err != nil {
klog.Errorf("PersistentVolumeController can't initialize caches: %v", err)
return
}
for _, volume := range volumeList {
// 我們不能改變 volume 對象，是以這裡我們copy一份新對象，對新對象進行操作
volumeClone := volume.DeepCopy()
if _, err = ctrl.storeVolumeUpdate(volumeClone); err != nil {
klog.Errorf("error updating volume cache: %v", err)
}
}
claimList, err := claimLister.List(labels.Everything())
if err != nil {
klog.Errorf("PersistentVolumeController can't initialize caches: %v", err)
return
}
for _, claim := range claimList {
if _, err = ctrl.storeClaimUpdate(claim.DeepCopy()); err != nil {
klog.Errorf("error updating claim cache: %v", err)
}
}
klog.V(4).Infof("controller initialized")
}
type persistentVolumeOrderedIndex struct {
store cache.Indexer
} 該方法将 cache.listener 裡面的緩存轉存在 persistentVolumeOrderedIndex 中，它是按 AccessModes 索引并按存儲容量排序的 persistentVolume 的緩存。
1 resync
func (ctrl *PersistentVolumeController) resync() {
klog.V(4).Infof("resyncing PV controller")
pvcs, err := ctrl.claimLister.List(labels.NewSelector())
if err != nil {
klog.Warningf("cannot list claims: %s", err)
return
}
for _, pvc := range pvcs {
ctrl.enqueueWork(ctrl.claimQueue, pvc)
}
pvs, err := ctrl.volumeLister.List(labels.NewSelector())
if err != nil {
klog.Warningf("cannot list persistent volumes: %s", err)
return
}
for _, pv := range pvs {
ctrl.enqueueWork(ctrl.volumeQueue, pv)
}
} 這裡将叢集内所有的 pvc/pv 統一都放到對應的 claimQueue & volumeQueue 裡面重新處理。 這個resyncPeriod 等于一個random time.Duration * config.time(在 kcm 啟動時設定)。
2 volumeWorker
一個無限循環， 不斷的處理從 volumeQueue 裡面擷取到的 PersistentVolume
workFunc := func() bool {
keyObj, quit := ctrl.volumeQueue.Get()
if quit {
return true
}
defer ctrl.volumeQueue.Done(keyObj)
key := keyObj.(string)
klog.V(5).Infof("volumeWorker[%s]", key)
_, name, err := cache.SplitMetaNamespaceKey(key)
if err != nil {
klog.V(4).Infof("error getting name of volume %q to get volume from informer: %v", key, err)
return false
}
volume, err := ctrl.volumeLister.Get(name)
if err == nil {
// The volume still exists in informer cache, the event must have
// been add/update/sync
ctrl.updateVolume(volume)
return false
}
if !errors.IsNotFound(err) {
klog.V(2).Infof("error getting volume %q from informer: %v", key, err)
return false
}
// The volume is not in informer cache, the event must have been
// "delete"
volumeObj, found, err := ctrl.volumes.store.GetByKey(key)
if err != nil {
klog.V(2).Infof("error getting volume %q from cache: %v", key, err)
return false
}
if !found {
// The controller has already processed the delete event and
// deleted the volume from its cache
klog.V(2).Infof("deletion of volume %q was already processed", key)
return false
}
volume, ok := volumeObj.(*v1.PersistentVolume)
if !ok {
klog.Errorf("expected volume, got %+v", volumeObj)
return false
}
ctrl.deleteVolume(volume)
return false
} 我們主要關注 ctrl.updateVolume(volume) 方法
updateVolume
updateVolume 方法是對于叢集内的 events 實際 handler 方法，它裡面主要調用了 ctrl.syncVolume 方法來處理
func (ctrl *PersistentVolumeController) syncVolume(ctx context.Context, volume *v1.PersistentVolume) error {
klog.V(4).Infof("synchronizing PersistentVolume[%s]: %s", volume.Name, getVolumeStatusForLogging(volume))
...
// [Unit test set 4]
if volume.Spec.ClaimRef == nil {
// Volume is unused
klog.V(4).Infof("synchronizing PersistentVolume[%s]: volume is unused", volume.Name)
if _, err := ctrl.updateVolumePhase(volume, v1.VolumeAvailable, ""); err != nil {
// Nothing was saved; we will fall back into the same
// condition in the next call to this method
return err
}
return nil
} else /* pv.Spec.ClaimRef != nil */ {
// Volume is bound to a claim.
if volume.Spec.ClaimRef.UID == "" {
// The PV is reserved for a PVC; that PVC has not yet been
// bound to this PV; the PVC sync will handle it.
klog.V(4).Infof("synchronizing PersistentVolume[%s]: volume is pre-bound to claim %s", volume.Name, claimrefToClaimKey(volume.Spec.ClaimRef))
if _, err := ctrl.updateVolumePhase(volume, v1.VolumeAvailable, ""); err != nil {
// Nothing was saved; we will fall back into the same
// condition in the next call to this method
return err
}
return nil
}
klog.V(4).Infof("synchronizing PersistentVolume[%s]: volume is bound to claim %s", volume.Name, claimrefToClaimKey(volume.Spec.ClaimRef))
// Get the PVC by _name_
var claim *v1.PersistentVolumeClaim
claimName := claimrefToClaimKey(volume.Spec.ClaimRef)
obj, found, err := ctrl.claims.GetByKey(claimName)
if err != nil {
return err
}
if !found {
if volume.Status.Phase != v1.VolumeReleased && volume.Status.Phase != v1.VolumeFailed {
obj, err = ctrl.claimLister.PersistentVolumeClaims(volume.Spec.ClaimRef.Namespace).Get(volume.Spec.ClaimRef.Name)
if err != nil && !apierrors.IsNotFound(err) {
return err
}
found = !apierrors.IsNotFound(err)
if !found {
obj, err = ctrl.kubeClient.CoreV1().PersistentVolumeClaims(volume.Spec.ClaimRef.Namespace).Get(context.TODO(), volume.Spec.ClaimRef.Name, metav1.GetOptions{})
if err != nil && !apierrors.IsNotFound(err) {
return err
}
found = !apierrors.IsNotFound(err)
}
}
}
if !found {
klog.V(4).Infof("synchronizing PersistentVolume[%s]: claim %s not found", volume.Name, claimrefToClaimKey(volume.Spec.ClaimRef))
// Fall through with claim = nil
} else {
var ok bool
claim, ok = obj.(*v1.PersistentVolumeClaim)
if !ok {
return fmt.Errorf("cannot convert object from volume cache to volume %q!?: %#v", claim.Spec.VolumeName, obj)
}
klog.V(4).Infof("synchronizing PersistentVolume[%s]: claim %s found: %s", volume.Name, claimrefToClaimKey(volume.Spec.ClaimRef), getClaimStatusForLogging(claim))
}
if claim != nil && claim.UID != volume.Spec.ClaimRef.UID {
klog.V(4).Infof("Maybe cached claim: %s is not the newest one, we should fetch it from apiserver", claimrefToClaimKey(volume.Spec.ClaimRef))
claim, err = ctrl.kubeClient.CoreV1().PersistentVolumeClaims(volume.Spec.ClaimRef.Namespace).Get(context.TODO(), volume.Spec.ClaimRef.Name, metav1.GetOptions{})
if err != nil && !apierrors.IsNotFound(err) {
return err
} else if claim != nil {
// Treat the volume as bound to a missing claim.
if claim.UID != volume.Spec.ClaimRef.UID {
klog.V(4).Infof("synchronizing PersistentVolume[%s]: claim %s has a newer UID than pv.ClaimRef, the old one must have been deleted", volume.Name, claimrefToClaimKey(volume.Spec.ClaimRef))
claim = nil
} else {
klog.V(4).Infof("synchronizing PersistentVolume[%s]: claim %s has a same UID with pv.ClaimRef", volume.Name, claimrefToClaimKey(volume.Spec.ClaimRef))
}
}
}
if claim == nil {
if volume.Status.Phase != v1.VolumeReleased && volume.Status.Phase != v1.VolumeFailed {
// Also, log this only once:
klog.V(2).Infof("volume %q is released and reclaim policy %q will be executed", volume.Name, volume.Spec.PersistentVolumeReclaimPolicy)
if volume, err = ctrl.updateVolumePhase(volume, v1.VolumeReleased, ""); err != nil {
// Nothing was saved; we will fall back into the same condition
// in the next call to this method
return err
}
}
if err = ctrl.reclaimVolume(volume); err != nil {
// Release failed, we will fall back into the same condition
// in the next call to this method
return err
}
if volume.Spec.PersistentVolumeReclaimPolicy == v1.PersistentVolumeReclaimRetain {
// volume is being retained, it references a claim that does not exist now.
klog.V(4).Infof("PersistentVolume[%s] references a claim %q (%s) that is not found", volume.Name, claimrefToClaimKey(volume.Spec.ClaimRef), volume.Spec.ClaimRef.UID)
}
return nil
} else if claim.Spec.VolumeName == "" {
if pvutil.CheckVolumeModeMismatches(&claim.Spec, &volume.Spec) {
volumeMsg := fmt.Sprintf("Cannot bind PersistentVolume to requested PersistentVolumeClaim %q due to incompatible volumeMode.", claim.Name)
ctrl.eventRecorder.Event(volume, v1.EventTypeWarning, events.VolumeMismatch, volumeMsg)
claimMsg := fmt.Sprintf("Cannot bind PersistentVolume %q to requested PersistentVolumeClaim due to incompatible volumeMode.", volume.Name)
ctrl.eventRecorder.Event(claim, v1.EventTypeWarning, events.VolumeMismatch, claimMsg)
// Skipping syncClaim
return nil
}
if metav1.HasAnnotation(volume.ObjectMeta, pvutil.AnnBoundByController) {
// The binding is not completed; let PVC sync handle it
klog.V(4).Infof("synchronizing PersistentVolume[%s]: volume not bound yet, waiting for syncClaim to fix it", volume.Name)
} else {
// Dangling PV; try to re-establish the link in the PVC sync
klog.V(4).Infof("synchronizing PersistentVolume[%s]: volume was bound and got unbound (by user?), waiting for syncClaim to fix it", volume.Name)
}
ctrl.claimQueue.Add(claimToClaimKey(claim))
return nil
} else if claim.Spec.VolumeName == volume.Name {
// Volume is bound to a claim properly, update status if necessary
klog.V(4).Infof("synchronizing PersistentVolume[%s]: all is bound", volume.Name)
if _, err = ctrl.updateVolumePhase(volume, v1.VolumeBound, ""); err != nil {
// Nothing was saved; we will fall back into the same
// condition in the next call to this method
return err
}
return nil
} else {
// Volume is bound to a claim, but the claim is bound elsewhere
if metav1.HasAnnotation(volume.ObjectMeta, pvutil.AnnDynamicallyProvisioned) && volume.Spec.PersistentVolumeReclaimPolicy == v1.PersistentVolumeReclaimDelete {
if volume.Status.Phase != v1.VolumeReleased && volume.Status.Phase != v1.VolumeFailed {
// Also, log this only once:
klog.V(2).Infof("dynamically volume %q is released and it will be deleted", volume.Name)
if volume, err = ctrl.updateVolumePhase(volume, v1.VolumeReleased, ""); err != nil {
// Nothing was saved; we will fall back into the same condition
// in the next call to this method
return err
}
}
if err = ctrl.reclaimVolume(volume); err != nil {
return err
}
return nil
} else {
if metav1.HasAnnotation(volume.ObjectMeta, pvutil.AnnBoundByController) {
klog.V(4).Infof("synchronizing PersistentVolume[%s]: volume is bound by controller to a claim that is bound to another volume, unbinding", volume.Name)
if err = ctrl.unbindVolume(volume); err != nil {
return err
}
return nil
} else {
// The PV must have been created with this ptr; leave it alone.
klog.V(4).Infof("synchronizing PersistentVolume[%s]: volume is bound by user to a claim that is bound to another volume, waiting for the claim to get unbound", volume.Name)
if err = ctrl.unbindVolume(volume); err != nil {
return err
}
return nil
}
}
}
}
} 1、當 pv 的 Spec.ClaimRef 的值為空的時候，說明目前 pv 未被使用，調用 ctrl.updateVolumePhase 使得 pv 進入 Available 狀态
2、當 pv 的 Spec.ClaimRef 的值不為空的時候， 說明目前 pv 已綁定一個pvc
- 當Spec.ClaimRef.UID 為空的時候，說明 pvc 還未綁定 pv， 調用ctrl.updateVolumePhase 使得 pv 進入 Available 狀态， 方法傳回，等待 pvc syncClaim 方法處理
- 使用 Spec.ClaimRef 相關的 pvc 資訊擷取 pv_controller緩存的pvc
- 如果 pvc 沒有找到
- 有可能是叢集壓力過大緩存沒有更新，則進一步從 informercache 中找，如果 informercache裡面還是沒有的話則進一步從apiserver中去找
- 這裡如果發現 非 Released & 非 Failed 的pv 經過上述步驟仍然找不到 pvc 的話，說明 pvc 被删除。在最新的kubernetes 版本中會檢查reclaimPoilcy，對 pv的狀态進行處理
- 找到 pvc 之後
1）如果 pvc 的 uid 和 Spec.ClaimRef.UID 不一緻，這樣一般是 pv 指向的 pvc 被删了，然後立即建立了一個同名的pvc， 而緩存還沒有更新，這時我們需要doublecheck一下，若 double check 之後依舊不存在，則判斷是pv綁定了一個不存在的pvc， 将pvc置為空，執行上述pvc 沒有找到的邏輯
2）如果pvc 的 volumeName 為空
- 檢查 pvc的 volumeMode 和 pv 的 volumeMode是否一緻，不一緻報 event 出來
- 如果發現有這個 pv 有 AnnBoundByController = "pv.kubernetes.io/bound-by-controller" 這個annotation 說明 pvc/pv 流程正在綁定中
- 将 pvc 放到 claimQueue 裡面， 讓 claimWorker 進行處理
3）如果 pvc.Spec.volumeName == pv.volumeName 的時候，直接将 pv 設定為 bound 狀态
4）如果 pvc.Spec.volumeName != pv.volumeName 的時候
- 如果是 pv 是動态建立的情況下，并且 pv 的 ReclaimPolicy 是 delete 的情況下， 說明 pvc 已經綁定了其他pv， 将 pv 置為 released 的狀态， 等待deleters 删除
- 如果 pv 不是動态建立的情況下，将 pv 的 ClaimRef 字段置為空，将其 unbound 掉
3 claimWorker
一個無限循環，不斷的處理從 claimQueue 裡面擷取到的 PersistentVolumeClaim
workFunc := func() bool {
keyObj, quit := ctrl.claimQueue.Get()
if quit {
return true
}
defer ctrl.claimQueue.Done(keyObj)
key := keyObj.(string)
klog.V(5).Infof("claimWorker[%s]", key)
namespace, name, err := cache.SplitMetaNamespaceKey(key)
if err != nil {
klog.V(4).Infof("error getting namespace & name of claim %q to get claim from informer: %v", key, err)
return false
}
claim, err := ctrl.claimLister.PersistentVolumeClaims(namespace).Get(name)
if err == nil {
// The claim still exists in informer cache, the event must have
// been add/update/sync
ctrl.updateClaim(claim)
return false
}
if !errors.IsNotFound(err) {
klog.V(2).Infof("error getting claim %q from informer: %v", key, err)
return false
}
// The claim is not in informer cache, the event must have been "delete"
claimObj, found, err := ctrl.claims.GetByKey(key)
if err != nil {
klog.V(2).Infof("error getting claim %q from cache: %v", key, err)
return false
}
if !found {
// The controller has already processed the delete event and
// deleted the claim from its cache
klog.V(2).Infof("deletion of claim %q was already processed", key)
return false
}
claim, ok := claimObj.(*v1.PersistentVolumeClaim)
if !ok {
klog.Errorf("expected claim, got %+v", claimObj)
return false
}
ctrl.deleteClaim(claim)
return false
} 我們主要關注 ctrl.updateClaim(claim) 方法, 與上面同樣，它裡面主要調用了 ctrl.syncClaim 方法來處理， 在 syncClaim 裡面根據 pvc 的狀态分别調用了 ctrl.syncUnboundClaim & ctrl.syncBoundClaim 方法來處理
syncUnboundClaim
func (ctrl *PersistentVolumeController) syncUnboundClaim(ctx context.Context, claim *v1.PersistentVolumeClaim) error {
if claim.Spec.VolumeName == "" {
// User did not care which PV they get.
delayBinding, err := pvutil.IsDelayBindingMode(claim, ctrl.classLister)
if err != nil {
return err
}
// [Unit test set 1]
volume, err := ctrl.volumes.findBestMatchForClaim(claim, delayBinding)
if err != nil {
klog.V(2).Infof("synchronizing unbound PersistentVolumeClaim[%s]: Error finding PV for claim: %v", claimToClaimKey(claim), err)
return fmt.Errorf("error finding PV for claim %q: %w", claimToClaimKey(claim), err)
}
if volume == nil {
klog.V(4).Infof("synchronizing unbound PersistentVolumeClaim[%s]: no volume found", claimToClaimKey(claim))
switch {
case delayBinding && !pvutil.IsDelayBindingProvisioning(claim):
if err = ctrl.emitEventForUnboundDelayBindingClaim(claim); err != nil {
return err
}
case storagehelpers.GetPersistentVolumeClaimClass(claim) != "":
if err = ctrl.provisionClaim(ctx, claim); err != nil {
return err
}
return nil
default:
ctrl.eventRecorder.Event(claim, v1.EventTypeNormal, events.FailedBinding, "no persistent volumes available for this claim and no storage class is set")
}
// Mark the claim as Pending and try to find a match in the next
// periodic syncClaim
if _, err = ctrl.updateClaimStatus(claim, v1.ClaimPending, nil); err != nil {
return err
}
return nil
} else /* pv != nil */ {
// Found a PV for this claim
// OBSERVATION: pvc is "Pending", pv is "Available"
claimKey := claimToClaimKey(claim)
klog.V(4).Infof("synchronizing unbound PersistentVolumeClaim[%s]: volume %q found: %s", claimKey, volume.Name, getVolumeStatusForLogging(volume))
if err = ctrl.bind(volume, claim); err != nil {
metrics.RecordMetric(claimKey, &ctrl.operationTimestamps, err)
return err
}
metrics.RecordMetric(claimKey, &ctrl.operationTimestamps, nil)
return nil
}
} else /* pvc.Spec.VolumeName != nil */ {
klog.V(4).Infof("synchronizing unbound PersistentVolumeClaim[%s]: volume %q requested", claimToClaimKey(claim), claim.Spec.VolumeName)
obj, found, err := ctrl.volumes.store.GetByKey(claim.Spec.VolumeName)
if err != nil {
return err
}
if !found {
klog.V(4).Infof("synchronizing unbound PersistentVolumeClaim[%s]: volume %q requested and not found, will try again next time", claimToClaimKey(claim), claim.Spec.VolumeName)
if _, err = ctrl.updateClaimStatus(claim, v1.ClaimPending, nil); err != nil {
return err
}
return nil
} else {
volume, ok := obj.(*v1.PersistentVolume)
if !ok {
return fmt.Errorf("cannot convert object from volume cache to volume %q!?: %+v", claim.Spec.VolumeName, obj)
}
klog.V(4).Infof("synchronizing unbound PersistentVolumeClaim[%s]: volume %q requested and found: %s", claimToClaimKey(claim), claim.Spec.VolumeName, getVolumeStatusForLogging(volume))
if volume.Spec.ClaimRef == nil {
klog.V(4).Infof("synchronizing unbound PersistentVolumeClaim[%s]: volume is unbound, binding", claimToClaimKey(claim))
if err = checkVolumeSatisfyClaim(volume, claim); err != nil {
klog.V(4).Infof("Can't bind the claim to volume %q: %v", volume.Name, err)
// send an event
msg := fmt.Sprintf("Cannot bind to requested volume %q: %s", volume.Name, err)
ctrl.eventRecorder.Event(claim, v1.EventTypeWarning, events.VolumeMismatch, msg)
// volume does not satisfy the requirements of the claim
if _, err = ctrl.updateClaimStatus(claim, v1.ClaimPending, nil); err != nil {
return err
}
} else if err = ctrl.bind(volume, claim); err != nil {
// On any error saving the volume or the claim, subsequent
// syncClaim will finish the binding.
return err
}
// OBSERVATION: pvc is "Bound", pv is "Bound"
return nil
} else if pvutil.IsVolumeBoundToClaim(volume, claim) {
// User asked for a PV that is claimed by this PVC
// OBSERVATION: pvc is "Pending", pv is "Bound"
klog.V(4).Infof("synchronizing unbound PersistentVolumeClaim[%s]: volume already bound, finishing the binding", claimToClaimKey(claim))
// Finish the volume binding by adding claim UID.
if err = ctrl.bind(volume, claim); err != nil {
return err
}
// OBSERVATION: pvc is "Bound", pv is "Bound"
return nil
} else {
// User asked for a PV that is claimed by someone else
// OBSERVATION: pvc is "Pending", pv is "Bound"
if !metav1.HasAnnotation(claim.ObjectMeta, pvutil.AnnBoundByController) {
klog.V(4).Infof("synchronizing unbound PersistentVolumeClaim[%s]: volume already bound to different claim by user, will retry later", claimToClaimKey(claim))
claimMsg := fmt.Sprintf("volume %q already bound to a different claim.", volume.Name)
ctrl.eventRecorder.Event(claim, v1.EventTypeWarning, events.FailedBinding, claimMsg)
// User asked for a specific PV, retry later
if _, err = ctrl.updateClaimStatus(claim, v1.ClaimPending, nil); err != nil {
return err
}
return nil
} else {
klog.V(4).Infof("synchronizing unbound PersistentVolumeClaim[%s]: volume already bound to different claim %q by controller, THIS SHOULD NEVER HAPPEN", claimToClaimKey(claim), claimrefToClaimKey(volume.Spec.ClaimRef))
claimMsg := fmt.Sprintf("volume %q already bound to a different claim.", volume.Name)
ctrl.eventRecorder.Event(claim, v1.EventTypeWarning, events.FailedBinding, claimMsg)
return fmt.Errorf("invalid binding of claim %q to volume %q: volume already claimed by %q", claimToClaimKey(claim), claim.Spec.VolumeName, claimrefToClaimKey(volume.Spec.ClaimRef))
}
}
}
}
} 梳理下整體流程
- 如果目前 pvc 的 volumeName 為空
- 判斷目前pvc 是否是延遲綁定的
- 調用 volume, err := ctrl.volumes.findBestMatchForClaim(claim, delayBinding) 找出對應的 pv
- 如果找到 volume 的話
- 調用 ctrl.bind(volume, claim) 方法進行綁定
- 如果沒有找到 volume 的話
- 如果是延遲綁定， 并且還未觸發（pod 未引用）則 emit event 到 pvc 上
- 如果 pvc 綁定了 sc, 調用 ctrl.provisionClaim(ctx, claim) 方法
- 分析 pvc yaml， 找到 provisioner driver
- 啟動一個 goroutine
- 調用 ctrl.provisionClaimOperation(ctx, claim, plugin, storageClass) 進行建立工作
provisionClaimOperation
func (ctrl *PersistentVolumeController) provisionClaimOperation(
ctx context.Context,
claim *v1.PersistentVolumeClaim,
plugin vol.ProvisionableVolumePlugin,
storageClass *storage.StorageClass) (string, error) {
claimClass := storagehelpers.GetPersistentVolumeClaimClass(claim)
klog.V(4).Infof("provisionClaimOperation [%s] started, class: %q", claimToClaimKey(claim), claimClass)
pluginName := plugin.GetPluginName()
if pluginName != "kubernetes.io/csi" && claim.Spec.DataSource != nil {
strerr := fmt.Sprintf("plugin %q is not a CSI plugin. Only CSI plugin can provision a claim with a datasource", pluginName)
return pluginName, fmt.Errorf(strerr)
}
provisionerName := storageClass.Provisioner
// Add provisioner annotation to be consistent with external provisioner workflow
newClaim, err := ctrl.setClaimProvisioner(ctx, claim, provisionerName)
if err != nil {
// Save failed, the controller will retry in the next sync
klog.V(2).Infof("error saving claim %s: %v", claimToClaimKey(claim), err)
return pluginName, err
}
claim = newClaim
pvName := ctrl.getProvisionedVolumeNameForClaim(claim)
volume, err := ctrl.kubeClient.CoreV1().PersistentVolumes().Get(context.TODO(), pvName, metav1.GetOptions{})
if err != nil && !apierrors.IsNotFound(err) {
klog.V(3).Infof("error reading persistent volume %q: %v", pvName, err)
return pluginName, err
}
if err == nil && volume != nil {
// Volume has been already provisioned, nothing to do.
klog.V(4).Infof("provisionClaimOperation [%s]: volume already exists, skipping", claimToClaimKey(claim))
return pluginName, err
}
// Prepare a claimRef to the claim early (to fail before a volume is
// provisioned)
claimRef, err := ref.GetReference(scheme.Scheme, claim)
if err != nil {
klog.V(3).Infof("unexpected error getting claim reference: %v", err)
return pluginName, err
}
// Gather provisioning options
tags := make(map[string]string)
tags[CloudVolumeCreatedForClaimNamespaceTag] = claim.Namespace
tags[CloudVolumeCreatedForClaimNameTag] = claim.Name
tags[CloudVolumeCreatedForVolumeNameTag] = pvName
options := vol.VolumeOptions{
PersistentVolumeReclaimPolicy: *storageClass.ReclaimPolicy,
MountOptions: storageClass.MountOptions,
CloudTags: &tags,
ClusterName: ctrl.clusterName,
PVName: pvName,
PVC: claim,
Parameters: storageClass.Parameters,
}
// Refuse to provision if the plugin doesn't support mount options, creation
// of PV would be rejected by validation anyway
if !plugin.SupportsMountOption() && len(options.MountOptions) > 0 {
strerr := fmt.Sprintf("Mount options are not supported by the provisioner but StorageClass %q has mount options %v", storageClass.Name, options.MountOptions)
klog.V(2).Infof("Mount options are not supported by the provisioner but claim %q's StorageClass %q has mount options %v", claimToClaimKey(claim), storageClass.Name, options.MountOptions)
ctrl.eventRecorder.Event(claim, v1.EventTypeWarning, events.ProvisioningFailed, strerr)
return pluginName, fmt.Errorf("provisioner %q doesn't support mount options", plugin.GetPluginName())
}
// Provision the volume
provisioner, err := plugin.NewProvisioner(options)
if err != nil {
strerr := fmt.Sprintf("Failed to create provisioner: %v", err)
klog.V(2).Infof("failed to create provisioner for claim %q with StorageClass %q: %v", claimToClaimKey(claim), storageClass.Name, err)
ctrl.eventRecorder.Event(claim, v1.EventTypeWarning, events.ProvisioningFailed, strerr)
return pluginName, err
}
var selectedNode *v1.Node = nil
if nodeName, ok := claim.Annotations[pvutil.AnnSelectedNode]; ok {
selectedNode, err = ctrl.NodeLister.Get(nodeName)
if err != nil {
strerr := fmt.Sprintf("Failed to get target node: %v", err)
klog.V(3).Infof("unexpected error getting target node %q for claim %q: %v", nodeName, claimToClaimKey(claim), err)
ctrl.eventRecorder.Event(claim, v1.EventTypeWarning, events.ProvisioningFailed, strerr)
return pluginName, err
}
}
allowedTopologies := storageClass.AllowedTopologies
opComplete := util.OperationCompleteHook(plugin.GetPluginName(), "volume_provision")
volume, err = provisioner.Provision(selectedNode, allowedTopologies)
opComplete(volumetypes.CompleteFuncParam{Err: &err})
if err != nil {
ctrl.rescheduleProvisioning(claim)
strerr := fmt.Sprintf("Failed to provision volume with StorageClass %q: %v", storageClass.Name, err)
klog.V(2).Infof("failed to provision volume for claim %q with StorageClass %q: %v", claimToClaimKey(claim), storageClass.Name, err)
ctrl.eventRecorder.Event(claim, v1.EventTypeWarning, events.ProvisioningFailed, strerr)
return pluginName, err
}
klog.V(3).Infof("volume %q for claim %q created", volume.Name, claimToClaimKey(claim))
// Create Kubernetes PV object for the volume.
if volume.Name == "" {
volume.Name = pvName
}
// Bind it to the claim
volume.Spec.ClaimRef = claimRef
volume.Status.Phase = v1.VolumeBound
volume.Spec.StorageClassName = claimClass
// Add AnnBoundByController (used in deleting the volume)
metav1.SetMetaDataAnnotation(&volume.ObjectMeta, pvutil.AnnBoundByController, "yes")
metav1.SetMetaDataAnnotation(&volume.ObjectMeta, pvutil.AnnDynamicallyProvisioned, plugin.GetPluginName())
// Try to create the PV object several times
for i := 0; i < ctrl.createProvisionedPVRetryCount; i++ {
klog.V(4).Infof("provisionClaimOperation [%s]: trying to save volume %s", claimToClaimKey(claim), volume.Name)
var newVol *v1.PersistentVolume
if newVol, err = ctrl.kubeClient.CoreV1().PersistentVolumes().Create(context.TODO(), volume, metav1.CreateOptions{}); err == nil || apierrors.IsAlreadyExists(err) {
// Save succeeded.
if err != nil {
klog.V(3).Infof("volume %q for claim %q already exists, reusing", volume.Name, claimToClaimKey(claim))
err = nil
} else {
klog.V(3).Infof("volume %q for claim %q saved", volume.Name, claimToClaimKey(claim))
_, updateErr := ctrl.storeVolumeUpdate(newVol)
if updateErr != nil {
// We will get an "volume added" event soon, this is not a big error
klog.V(4).Infof("provisionClaimOperation [%s]: cannot update internal cache: %v", volume.Name, updateErr)
}
}
break
}
// Save failed, try again after a while.
klog.V(3).Infof("failed to save volume %q for claim %q: %v", volume.Name, claimToClaimKey(claim), err)
time.Sleep(ctrl.createProvisionedPVInterval)
}
if err != nil {
strerr := fmt.Sprintf("Error creating provisioned PV object for claim %s: %v. Deleting the volume.", claimToClaimKey(claim), err)
klog.V(3).Info(strerr)
ctrl.eventRecorder.Event(claim, v1.EventTypeWarning, events.ProvisioningFailed, strerr)
var deleteErr error
var deleted bool
for i := 0; i < ctrl.createProvisionedPVRetryCount; i++ {
_, deleted, deleteErr = ctrl.doDeleteVolume(volume)
if deleteErr == nil && deleted {
// Delete succeeded
klog.V(4).Infof("provisionClaimOperation [%s]: cleaning volume %s succeeded", claimToClaimKey(claim), volume.Name)
break
}
if !deleted {
klog.Errorf("Error finding internal deleter for volume plugin %q", plugin.GetPluginName())
break
}
// Delete failed, try again after a while.
klog.V(3).Infof("failed to delete volume %q: %v", volume.Name, deleteErr)
time.Sleep(ctrl.createProvisionedPVInterval)
}
if deleteErr != nil {
strerr := fmt.Sprintf("Error cleaning provisioned volume for claim %s: %v. Please delete manually.", claimToClaimKey(claim), deleteErr)
klog.V(2).Info(strerr)
ctrl.eventRecorder.Event(claim, v1.EventTypeWarning, events.ProvisioningCleanupFailed, strerr)
}
} else {
klog.V(2).Infof("volume %q provisioned for claim %q", volume.Name, claimToClaimKey(claim))
msg := fmt.Sprintf("Successfully provisioned volume %s using %s", volume.Name, plugin.GetPluginName())
ctrl.eventRecorder.Event(claim, v1.EventTypeNormal, events.ProvisioningSucceeded, msg)
}
return pluginName, nil
} provisionClaimOperation 的基本邏輯如下
- 檢查driver，隻有 csi 類型的 driver 才允許使用 dataSource 字段
- 為 pvc 加 claim.Annotations["volume.kubernetes.io/storage-provisioner"] = class.Provisioner annotation
- 根據規則拼出 pv Name = "pvc-" + pvc.UID
- 如果找到了 pv， 則說明 pv已經存在，跳過 provision
- 收集pvc/pv 基本資訊封裝到 options 中
- 對 plugin 進行校驗， 如果plugin不支援mount操作，則直接拒絕provision 請求
- 調用plugin.NewProvisioner(options) 建立 provisioner， 接口實作了Provision(selectedNode *v1.Node, allowedTopologies []v1.TopologySelectorTerm) 方法，注意，該方法為同步方法
- Provision 方法傳回了 PersistentVolume執行個體
- 為建立出來的 pv 關聯 pvc 對象（ClaimRef），嘗試建立 pv 對象 (重複多次)
- 如果建立 pv 失敗，則嘗試調用 Delete 方法删除建立的volume資源
syncBoundClaim
func (ctrl *PersistentVolumeController) syncBoundClaim(claim *v1.PersistentVolumeClaim) error {
if claim.Spec.VolumeName == "" {
// Claim was bound before but not any more.
if _, err := ctrl.updateClaimStatusWithEvent(claim, v1.ClaimLost, nil, v1.EventTypeWarning, "ClaimLost", "Bound claim has lost reference to PersistentVolume. Data on the volume is lost!"); err != nil {
return err
}
return nil
}
obj, found, err := ctrl.volumes.store.GetByKey(claim.Spec.VolumeName)
if err != nil {
return err
}
if !found {
// Claim is bound to a non-existing volume.
if _, err = ctrl.updateClaimStatusWithEvent(claim, v1.ClaimLost, nil, v1.EventTypeWarning, "ClaimLost", "Bound claim has lost its PersistentVolume. Data on the volume is lost!"); err != nil {
return err
}
return nil
} else {
volume, ok := obj.(*v1.PersistentVolume)
if !ok {
return fmt.Errorf("cannot convert object from volume cache to volume %q!?: %#v", claim.Spec.VolumeName, obj)
}
klog.V(4).Infof("synchronizing bound PersistentVolumeClaim[%s]: volume %q found: %s", claimToClaimKey(claim), claim.Spec.VolumeName, getVolumeStatusForLogging(volume))
if volume.Spec.ClaimRef == nil {
// Claim is bound but volume has come unbound.
// Or, a claim was bound and the controller has not received updated
// volume yet. We can't distinguish these cases.
// Bind the volume again and set all states to Bound.
klog.V(4).Infof("synchronizing bound PersistentVolumeClaim[%s]: volume is unbound, fixing", claimToClaimKey(claim))
if err = ctrl.bind(volume, claim); err != nil {
// Objects not saved, next syncPV or syncClaim will try again
return err
}
return nil
} else if volume.Spec.ClaimRef.UID == claim.UID {
// All is well
// NOTE: syncPV can handle this so it can be left out.
// NOTE: bind() call here will do nothing in most cases as
// everything should be already set.
klog.V(4).Infof("synchronizing bound PersistentVolumeClaim[%s]: claim is already correctly bound", claimToClaimKey(claim))
if err = ctrl.bind(volume, claim); err != nil {
// Objects not saved, next syncPV or syncClaim will try again
return err
}
return nil
} else {
// Claim is bound but volume has a different claimant.
// Set the claim phase to 'Lost', which is a terminal
// phase.
if _, err = ctrl.updateClaimStatusWithEvent(claim, v1.ClaimLost, nil, v1.EventTypeWarning, "ClaimMisbound", "Two claims are bound to the same volume, this one is bound incorrectly"); err != nil {
return err
}
return nil
}
}
}
1）如果 pvc.Spec.VolumeName 為空, 說明這個 pvc 之前被 bound 過，但是已經不存在指向的pv， 報出event并傳回
2）從 cache 裡面找 pvc 綁定的 pv
- 如果沒找到, 說明 pvc 綁定了一個不存在的pv，報 event 并傳回
- 如果找到了pv
-
- 檢查 pv.Spec.ClaimRef 字段， 如果 為空，說明 pv 還沒有綁定 pvc， 調用 ctrl.bind(volume, claim); 方法進行綁定
- pv.ClaimRef.UID == pvc.UID, 調用 bind 方法，但是大多數情況會直接傳回（因為所有的操作都已經做完了）
- 其他情況說明 volume 綁定了其他的 pvc， 更新pvc 的狀态 為 lost 并報出 event
四 總結
最後用一張 pvc/pv 的狀态流轉圖來總結一下
如何通過Knative輕松實作應用Serverless化傳遞
本課程将會為你介紹如何通過Knative輕松完成應用在Serverless k8s的部署，并實作應用的按比例灰階釋出和基于qps的彈性伸縮。
點選這裡，檢視詳情。