Skip to main content

Question 2 - Pod Scheduling on Control Plane

Question 2 | Schedule Pod on Controlplane Nodes​

Use context: kubectl config use-context k8s-c1-H

Create a single Pod of image httpd:2.4.41-alpine in Namespace default. The Pod should be named pod1 and the container should be named pod1-container. This Pod should only be scheduled on controlplane nodes. Do not add new labels to any nodes.

Let's check the taints

k get node # find controlplane node

k describe node cluster1-controlplane1 | grep Taint -A1 # get controlplane node taints
k get node cluster1-controlplane1 --show-labels # get controlplane node labels

# Creating a template for the pod to be applied later
k run pod1 --image=httpd:2.4.41-alpine --dry-run=client -o yaml > 2.yaml
vim 2.yaml
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod1
  name: pod1
spec:
  containers:
  - image: httpd:2.4.41-alpine
    name: pod1-container                       # change
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
  tolerations:                                 # add
  - effect: NoSchedule                         # add
    key: node-role.kubernetes.io/control-plane # add
  nodeSelector:                                # add
    node-role.kubernetes.io/control-plane: ""  # add
status: {}

The toleration is necessary, otherwise even if we select the control plane node it won't execute.

k -f 2.yaml create
k get pod pod1 -o wide

NAME   READY   STATUS    RESTARTS   ...    NODE                     NOMINATED NODE
pod1   1/1     Running   0          ...    cluster1-controlplane1   <none>