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PV controller: don't delete PVs when PVC is not known yet

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Normally, the PV controller knows about the PVC that triggers the
creation of a PV before it sees the PV, because the PV controller must
set the volume.beta.kubernetes.io/storage-provisioner annotation that
tells an external provisioner to create the PV.

When restarting, the PV controller first syncs its caches, so that
case is also covered.

However, the creator of a PVC might decided to set that annotation
itself to speed up volume creation. While unusual, it's not forbidden
and thus part of the external Kubernetes API. Whether it makes sense
depends on the intentions of the user.

When that is done and there is heavy load, an external provisioner
might see the PVC and create a PV before the PV controller sees the
PVC. If the PV controller then encounters the PV before the PVC, it
incorrectly concludes that the PV needs to be deleted instead of being
bound.

The same issue occurred earlier for external binding and the existing
code for looking up a PVC in the cache or in the apiserver solves the
issue also for volume provisioning, it just needs to be enabled also
for PVs without the pv.kubernetes.io/bound-by-controller annotation.
This commit is contained in:
Patrick Ohly 2020-10-27 11:16:58 +01:00
parent 1c6057b59c
commit 5686664a1d
1 changed files with 4 additions and 3 deletions
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7
pkg/controller/volume/persistentvolume/pv_controller.go
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@ -577,9 +577,10 @@ func (ctrl *PersistentVolumeController) syncVolume(volume *v1.PersistentVolume)
if err != nil { if err != nil {
return err return err
} }
if !found && metav1.HasAnnotation(volume.ObjectMeta, pvutil.AnnBoundByController) { if !found {
// If PV is bound by external PV binder (e.g. kube-scheduler), it's // If the PV was created by an external PV provisioner or
// possible on heavy load that corresponding PVC is not synced to // bound by external PV binder (e.g. kube-scheduler), it's
// possible under heavy load that the corresponding PVC is not synced to
// controller local cache yet. So we need to double-check PVC in // controller local cache yet. So we need to double-check PVC in
// 1) informer cache // 1) informer cache
// 2) apiserver if not found in informer cache // 2) apiserver if not found in informer cache