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[snapshot-controller] Retry PVC finalizer removal on conflict #1133

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Merged
merged 1 commit into from
Aug 28, 2024
+126 −12
Merged

[snapshot-controller] Retry PVC finalizer removal on conflict #1133

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28 changes: 16 additions & 12 deletions pkg/common-controller/snapshot_controller.go
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ import (
"k8s.io/apimachinery/pkg/labels"
"k8s.io/client-go/kubernetes/scheme"
ref "k8s.io/client-go/tools/reference"
"k8s.io/client-go/util/retry"
corev1helpers "k8s.io/component-helpers/scheduling/corev1"
klog "k8s.io/klog/v2"

Expand Down Expand Up @@ -930,19 +931,22 @@ func (ctrl *csiSnapshotCommonController) ensurePVCFinalizer(snapshot *crdv1.Volu

// removePVCFinalizer removes a Finalizer for VolumeSnapshot Source PVC.
func (ctrl *csiSnapshotCommonController) removePVCFinalizer(pvc *v1.PersistentVolumeClaim) error {
// Get snapshot source which is a PVC
// TODO(xyang): We get PVC from informer but it may be outdated
// Should get it from API server directly before removing finalizer
pvcClone := pvc.DeepCopy()
pvcClone.ObjectMeta.Finalizers = utils.RemoveString(pvcClone.ObjectMeta.Finalizers, utils.PVCFinalizer)

_, err := ctrl.client.CoreV1().PersistentVolumeClaims(pvcClone.Namespace).Update(context.TODO(), pvcClone, metav1.UpdateOptions{})
if err != nil {
return newControllerUpdateError(pvcClone.Name, err.Error())
}
return retry.RetryOnConflict(retry.DefaultRetry, func() error {
// Get snapshot source which is a PVC
newPvc, err := ctrl.client.CoreV1().PersistentVolumeClaims(pvc.Namespace).Get(context.TODO(), pvc.Name, metav1.GetOptions{})
if err != nil {
return err
}
newPvc = newPvc.DeepCopy()
newPvc.ObjectMeta.Finalizers = utils.RemoveString(newPvc.ObjectMeta.Finalizers, utils.PVCFinalizer)
_, err = ctrl.client.CoreV1().PersistentVolumeClaims(newPvc.Namespace).Update(context.TODO(), newPvc, metav1.UpdateOptions{})
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Using a "patch" instead of an "update" can reduce the conflicts.

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I do agree that a using a "patch" would get rid of all the conflicts however since the finalizers are stored in a list, using a patch seems dangerous to me because if the finalizer list changes between the get and update calls (because another controller removed its finalizer for instance), it means that we would end up removing the wrong finalizer (since we need the index to remove an element from a list using a patch).

Is there something I'm missing that could let us use a patch instead without the drawback above?

if err != nil {
return newControllerUpdateError(newPvc.Name, err.Error())
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folks, I suspect generating a new error here (newControllerUpdateError) results in IsConflict never evaluating to true, and thus the original problem still existing. I hit this on an environment with 8.2.0 which contains this commit.

I can open a PR to tackle

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#1299

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Hi @akalenyu sorry about this! I actually did notice it a while back and made a PR in our fork to make sure this fixed the behavior for good (which it did) but I forgot to upstream it :(

}

klog.V(5).Infof("Removed protection finalizer from persistent volume claim %s", pvc.Name)
return nil
klog.V(5).Infof("Removed protection finalizer from persistent volume claim %s", pvc.Name)
return nil
})
}

// isPVCBeingUsed checks if a PVC is being used as a source to create a snapshot.
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4 changes: 4 additions & 0 deletions vendor/k8s.io/client-go/util/retry/OWNERS
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105 changes: 105 additions & 0 deletions vendor/k8s.io/client-go/util/retry/util.go
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1 change: 1 addition & 0 deletions vendor/modules.txt
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Expand Up @@ -770,6 +770,7 @@ k8s.io/client-go/util/consistencydetector
k8s.io/client-go/util/flowcontrol
k8s.io/client-go/util/homedir
k8s.io/client-go/util/keyutil
k8s.io/client-go/util/retry
k8s.io/client-go/util/watchlist
k8s.io/client-go/util/workqueue
# k8s.io/component-base v0.31.0-rc.0 => k8s.io/component-base v0.31.0-rc.0
Expand Down