add label to a node from within the cluster

label-node-incluster.yaml

---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: kata-label-node
  namespace: default
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: node-labeler
rules:
- apiGroups: [""]
  resources: ["nodes"]
  verbs: ["get", "patch"]
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: kata-label-node-rb
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: node-labeler
subjects:
- kind: ServiceAccount
  name: kata-label-node
  namespace: default
---
apiVersion: v1
kind: Pod
metadata:
  name: kata-label-node-pod
spec:
  serviceAccountName: kata-label-node
  containers:
    - name: test-container
      image: lachlanevenson/k8s-kubectl
      command: [ "sh", "-c"]
      args:
      - printenv MY_NODE_NAME;
        kubectl get node $MY_NODE_NAME --show-labels;
        kubectl label nodes $MY_NODE_NAME kata-runtime=true;
        kubectl get node $MY_NODE_NAME --show-labels;
      env:
        - name: MY_NODE_NAME
          valueFrom:
            fieldRef:
              fieldPath: spec.nodeName
  restartPolicy: Never