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NodeLifecycleController: Remove race condition

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Patch request does not support RV by default, we need to include them explicitly and patching lists actually overwrites whole field. It means that there is a race condition, in which we can overwrite changes to taints that happened between GET and PATCH requests.
This commit is contained in:
Jakub Przychodzeń
2022-10-18 12:01:15 +00:00
parent 83415e5c9e
commit de25c5fdcf
5 changed files with 70 additions and 8 deletions
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11
pkg/controller/controller_utils.go
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@@ -1127,9 +1127,14 @@ func RemoveTaintOffNode(ctx context.Context, c clientset.Interface, nodeName str
// PatchNodeTaints patches node's taints.
func PatchNodeTaints(ctx context.Context, c clientset.Interface, nodeName string, oldNode *v1.Node, newNode *v1.Node) error {
oldData, err := json.Marshal(oldNode)
// Strip base diff node from RV to ensure that our Patch request will set RV to check for conflicts over .spec.taints.
// This is needed because .spec.taints does not specify patchMergeKey and patchStrategy and adding them is no longer an option for compatibility reasons.
// Using other Patch strategy works for adding new taints, however will not resolve problem with taint removal.
oldNodeNoRV := oldNode.DeepCopy()
oldNodeNoRV.ResourceVersion = ""
oldDataNoRV, err := json.Marshal(&oldNodeNoRV)
if err != nil {
return fmt.Errorf("failed to marshal old node %#v for node %q: %v", oldNode, nodeName, err)
return fmt.Errorf("failed to marshal old node %#v for node %q: %v", oldNodeNoRV, nodeName, err)
}
newTaints := newNode.Spec.Taints
@@ -1140,7 +1145,7 @@ func PatchNodeTaints(ctx context.Context, c clientset.Interface, nodeName string
return fmt.Errorf("failed to marshal new node %#v for node %q: %v", newNodeClone, nodeName, err)
}
patchBytes, err := strategicpatch.CreateTwoWayMergePatch(oldData, newData, v1.Node{})
patchBytes, err := strategicpatch.CreateTwoWayMergePatch(oldDataNoRV, newData, v1.Node{})
if err != nil {
return fmt.Errorf("failed to create patch for node %q: %v", nodeName, err)
}