kubernetes pv-controller 解析

基于 kubernetes 1.23

一简介

pv controller是 kcm 的组件之一，它负责处理集群中的pvc/pv对象，对pvc/pv 对象进行状态转换。

二 pvController 初始化

初始化代码在 pkg/controller/volume/persistentvolume/pv_controller_base.go 文件中，NewController 主要做了如下几件事情

初始化 eventRecorder

初始化 PersistentVolumeController 对象，

调用 VolumePluginMgr.InitPlugins() 方法初始化存储插件，代码存在于 pkg/volume/plugins.go 文件中

开始创建 informer 监听集群内的资源，初始化了如下 informer

PersistentVolumeInformer
PersistentVolumeClaimInformer
StorageClassInformer
PodInformer
NodeInformer

将 PV & PVC 的 event 分别放入 volumeQueue & claimQueue

为了不每次都迭代 pods ，自定义一个通过 pvc 键索引 pod 的索引器

初始化 intree 存储 -> csi 迁移相关功能的 manager

NewController代码在cmd/kube-controller-manager代码里面被调用，初始化成功之后紧接着调用go Run()方法运行 pvController

三开始运行

// 开始运行 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}

同步缓存之后开始周期性执行 ctrl.resync,ctrl.volumeWorker , ctrl.claimWorker , 我们看下 initalizeCaches 方法

func (ctrl *PersistentVolumeController) initializeCaches(volumeLister corelisters.PersistentVolumeLister, claimLister corelisters.PersistentVolumeClaimLister) {

// 这里不访问 apiserver，是从本地缓存拿出的对象，这些对象不可以被外部函数修改 volumeList, err := volumeLister.List(labels.Everything()) if err != nil { klog.Errorf("PersistentVolumeController can't initialize caches: %v", err) return } for _, volume := range volumeList { // 我们不能改变 volume 对象，所以这里我们copy一份新对象，对新对象进行操作 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}

该方法将 cache.listener 里面的缓存转存在 persistentVolumeOrderedIndex 中，它是按 AccessModes 索引并按存储容量排序的 persistentVolume 的缓存。

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) }}

这里将集群内所有的 pvc/pv 统一都放到对应的 claimQueue & volumeQueue 里面重新处理。这个resyncPeriod 等于一个random time.Duration * config.time(在 kcm 启动时设置)。

2 volumeWorker

一个无限循环，不断的处理从 volumeQueue 里面获取到的 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 }

我们主要关注 ctrl.updateVolume(volume) 方法

updateVolume

updateVolume 方法是对于集群内的 events 实际 handler 方法，它里面主要调用了 ctrl.syncVolume 方法来处理

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、当 pv 的 Spec.ClaimRef 的值为空的时候，说明当前 pv 未被使用，调用 ctrl.updateVolumePhase 使得 pv 进入 Available 状态

2、当 pv 的 Spec.ClaimRef 的值不为空的时候，说明当前 pv 已绑定一个pvc

当Spec.ClaimRef.UID 为空的时候，说明 pvc 还未绑定 pv，调用ctrl.updateVolumePhase 使得 pv 进入 Available 状态，方法返回，等待 pvc syncClaim 方法处理

使用 Spec.ClaimRef 相关的 pvc 信息获取 pv_controller缓存的pvc

如果 pvc 没有找到

有可能是集群压力过大缓存没有更新，则进一步从 informercache 中找，如果 informercache里面还是没有的话则进一步从apiserver中去找

这里如果发现非 Released & 非 Failed 的pv 经过上述步骤仍然找不到 pvc 的话，说明 pvc 被删除。在最新的kubernetes 版本中会检查reclaimPoilcy，对 pv的状态进行处理

找到 pvc 之后

1）如果 pvc 的 uid 和 Spec.ClaimRef.UID 不一致，这样一般是 pv 指向的 pvc 被删了，然后立即创建了一个同名的pvc，而缓存还没有更新，这时我们需要doublecheck一下，若 double check 之后依旧不存在，则判断是pv绑定了一个不存在的pvc，将pvc置为空，执行上述pvc 没有找到的逻辑

2）如果pvc 的 volumeName 为空

检查 pvc的 volumeMode 和 pv 的 volumeMode是否一致，不一致报 event 出来
如果发现有这个 pv 有 AnnBoundByController = "pv.kubernetes.io/bound-by-controller" 这个annotation 说明 pvc/pv 流程正在绑定中
将 pvc 放到 claimQueue 里面，让 claimWorker 进行处理

3）如果 pvc.Spec.volumeName == pv.volumeName 的时候，直接将 pv 设置为 bound 状态

4）如果 pvc.Spec.volumeName != pv.volumeName 的时候

如果是 pv 是动态创建的情况下，并且 pv 的 ReclaimPolicy 是 delete 的情况下，说明 pvc 已经绑定了其他pv，将 pv 置为 released 的状态，等待deleters 删除
如果 pv 不是动态创建的情况下，将 pv 的 ClaimRef 字段置为空，将其 unbound 掉

3 claimWorker

一个无限循环，不断的处理从 claimQueue 里面获取到的 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 }

我们主要关注 ctrl.updateClaim(claim) 方法, 与上面同样，它里面主要调用了 ctrl.syncClaim 方法来处理，在 syncClaim 里面根据 pvc 的状态分别调用了 ctrl.syncUnboundClaim & ctrl.syncBoundClaim 方法来处理

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))

} } } }}

梳理下整体流程

如果当前 pvc 的 volumeName 为空

判断当前pvc 是否是延迟绑定的
调用 volume, err := ctrl.volumes.findBestMatchForClaim(claim, delayBinding) 找出对应的 pv

如果找到 volume 的话

调用 ctrl.bind(volume, claim) 方法进行绑定

如果没有找到 volume 的话

如果是延迟绑定，并且还未触发（pod 未引用）则 emit event 到 pvc 上
如果 pvc 绑定了 sc, 调用 ctrl.provisionClaim(ctx, claim) 方法

分析 pvc yaml，找到 provisioner driver

启动一个 goroutine

调用 ctrl.provisionClaimOperation(ctx, claim, plugin, storageClass) 进行创建工作

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 的基本逻辑如下

检查driver，只有 csi 类型的 driver 才允许使用 dataSource 字段

为 pvc 加 claim.Annotations["volume.kubernetes.io/storage-provisioner"] = class.Provisioner annotation

根据规则拼出 pv Name = "pvc-" + pvc.UID

如果找到了 pv，则说明 pv已经存在，跳过 provision

收集pvc/pv 基本信息封装到 options 中

对 plugin 进行校验，如果plugin不支持mount操作，则直接拒绝provision 请求

调用plugin.NewProvisioner(options) 创建 provisioner，接口实现了Provision(selectedNode *v1.Node, allowedTopologies []v1.TopologySelectorTerm) 方法，注意，该方法为同步方法

Provision 方法返回了 PersistentVolume实例

为创建出来的 pv 关联 pvc 对象（ClaimRef），尝试创建 pv 对象 (重复多次)

如果创建 pv 失败，则尝试调用 Delete 方法删除创建的volume资源

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 为空, 说明这个 pvc 之前被 bound 过，但是已经不存在指向的pv，报出event并返回

2）从 cache 里面找 pvc 绑定的 pv

如果没找到, 说明 pvc 绑定了一个不存在的pv，报 event 并返回
如果找到了pv

检查 pv.Spec.ClaimRef 字段，如果为空，说明 pv 还没有绑定 pvc，调用 ctrl.bind(volume, claim); 方法进行绑定
pv.ClaimRef.UID == pvc.UID, 调用 bind 方法，但是大多数情况会直接返回（因为所有的操作都已经做完了）
其他情况说明 volume 绑定了其他的 pvc，更新pvc 的状态为 lost 并报出 event

四总结

最后用一张 pvc/pv 的状态流转图来总结一下

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