作者 | 牧琦
来源 | 阿里技术公众号
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
如何通过Knative轻松实现应用Serverless化交付
本课程将会为你介绍如何通过Knative轻松完成应用在Serverless k8s的部署，并实现应用的按比例灰度发布和基于qps的弹性伸缩。
