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Merge pull request #63167 from liggitt/taint-modification

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Automatic merge from submit-queue (batch tested with PRs 63167, 63357). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Prevent nodes from updating taints

Prevents kubelets from modifying or removing taints on update.

Nodes can set taints when they register themselves, but do not update/remove those taints after creation (that is done by the node controller based on reported node conditions).

xref https://github.com/kubernetes/community/pull/911 https://github.com/kubernetes/features/issues/279

/sig node
/sig auth
/sig scheduling

/assign @mikedanese @k82cn

```release-note
The NodeRestriction admission plugin now prevents kubelets from modifying/removing taints applied to their Node API object.
```
This commit is contained in:
Kubernetes Submit Queue 2018-05-15 21:18:08 -07:00 committed by GitHub
commit d723028d09
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2 changed files with 39 additions and 1 deletions
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6
plugin/pkg/admission/noderestriction/admission.go
View File

@ -338,6 +338,12 @@ func (c *nodePlugin) admitNode(nodeName string, a admission.Attributes) error {
if node.Spec.ConfigSource != nil && !apiequality.Semantic.DeepEqual(node.Spec.ConfigSource, oldNode.Spec.ConfigSource) {
return admission.NewForbidden(a, fmt.Errorf("cannot update configSource to a new non-nil configSource"))
}
// Don't allow a node to update its own taints. This would allow a node to remove or modify its
// taints in a way that would let it steer disallowed workloads to itself.
if !apiequality.Semantic.DeepEqual(node.Spec.Taints, oldNode.Spec.Taints) {
return admission.NewForbidden(a, fmt.Errorf("cannot modify taints"))
}
}
return nil

32
plugin/pkg/admission/noderestriction/admission_test.go
View File

@ -105,6 +105,8 @@ func Test_nodePlugin_Admit(t *testing.T) {
UID: "quxUID",
KubeletConfigKey: "kubelet",
}}}}
mynodeObjTaintA = &api.Node{ObjectMeta: mynodeObjMeta, Spec: api.NodeSpec{Taints: []api.Taint{{Key: "mykey", Value: "A"}}}}
mynodeObjTaintB = &api.Node{ObjectMeta: mynodeObjMeta, Spec: api.NodeSpec{Taints: []api.Taint{{Key: "mykey", Value: "B"}}}}
othernodeObj = &api.Node{ObjectMeta: metav1.ObjectMeta{Name: "othernode"}}
mymirrorpod = makeTestPod("ns", "mymirrorpod", "mynode", true)
@ -633,6 +635,12 @@ func Test_nodePlugin_Admit(t *testing.T) {
attributes: admission.NewAttributesRecord(mynodeObj, nil, nodeKind, mynodeObj.Namespace, "", nodeResource, "", admission.Create, mynode),
err: "",
},
{
name: "allow create of my node with taints",
podsGetter: noExistingPods,
attributes: admission.NewAttributesRecord(mynodeObjTaintA, nil, nodeKind, mynodeObj.Namespace, "", nodeResource, "", admission.Create, mynode),
err: "",
},
{
name: "allow update of my node",
podsGetter: existingPods,
@ -681,6 +689,30 @@ func Test_nodePlugin_Admit(t *testing.T) {
attributes: admission.NewAttributesRecord(mynodeObj, mynodeObjConfigA, nodeKind, mynodeObj.Namespace, mynodeObj.Name, nodeResource, "", admission.Update, mynode),
err: "",
},
{
name: "allow update of my node: no change to taints",
podsGetter: existingPods,
attributes: admission.NewAttributesRecord(mynodeObjTaintA, mynodeObjTaintA, nodeKind, mynodeObj.Namespace, mynodeObj.Name, nodeResource, "", admission.Update, mynode),
err: "",
},
{
name: "forbid update of my node: add taints",
podsGetter: existingPods,
attributes: admission.NewAttributesRecord(mynodeObjTaintA, mynodeObj, nodeKind, mynodeObj.Namespace, mynodeObj.Name, nodeResource, "", admission.Update, mynode),
err: "cannot modify taints",
},
{
name: "forbid update of my node: remove taints",
podsGetter: existingPods,
attributes: admission.NewAttributesRecord(mynodeObj, mynodeObjTaintA, nodeKind, mynodeObj.Namespace, mynodeObj.Name, nodeResource, "", admission.Update, mynode),
err: "cannot modify taints",
},
{
name: "forbid update of my node: change taints",
podsGetter: existingPods,
attributes: admission.NewAttributesRecord(mynodeObjTaintA, mynodeObjTaintB, nodeKind, mynodeObj.Namespace, mynodeObj.Name, nodeResource, "", admission.Update, mynode),
err: "cannot modify taints",
},
// Other node object
{