Merge pull request #29019 from SergeyKanzhelev/nodeRegistrationRequired

Node re-registration required to update the node labels

Author: k8s-ci-robot

content/en/docs/concepts/architecture/nodes.md

@@ -72,7 +72,8 @@ The name of a Node object must be a valid
 The [name](/docs/concepts/overview/working-with-objects/names#names) identifies a Node. Two Nodes
 cannot have the same name at the same time. Kubernetes also assumes that a resource with the same
 name is the same object. In case of a Node, it is implicitly assumed that an instance using the
-same name will have the same state (e.g. network settings, root disk contents). This may lead to
+same name will have the same state (e.g. network settings, root disk contents)
+and attributes like node labels. This may lead to
 inconsistencies if an instance was modified without changing its name. If the Node needs to be
 replaced or updated significantly, the existing Node object needs to be removed from API server
 first and re-added after the update.
@@ -98,6 +99,21 @@ When the [Node authorization mode](/docs/reference/access-authn-authz/node/) and
 [NodeRestriction admission plugin](/docs/reference/access-authn-authz/admission-controllers/#noderestriction) are enabled,
 kubelets are only authorized to create/modify their own Node resource.
 
+{{< note >}}
+As mentioned in the [Node name uniqueness](#node-name-uniqueness) section,
+when Node configuration needs to be updated, it is a good practice to re-register
+the node with the API server. For example, if the kubelet being restarted with
+the new set of `--node-labels`, but the same Node name is used, the change will
+not take an effect, as labels are being set on the Node registration.
+
+Pods already scheduled on the Node may misbehave or cause issues if the Node
+configuration will be changed on kubelet restart. For example, already running
+Pod may be tainted against the new labels assigned to the Node, while other
+Pods, that are incompatible with that Pod will be scheduled based on this new
+label.  Node re-registration ensures all Pods will be drained and properly
+re-scheduled.
+{{< /note >}}
+
 ### Manual Node administration
 
 You can create and modify Node objects using