Manually Scheduling a Pod

In some scenario you need to manually schedule a pod

Scheduler populates nodeName
If you specify nodeName in your Pod definition the Pod will be started on that node
Node's name must exist
Still subject to Node resource constraints

Demo

Manually scheduling a Pod by specifying nodeName

Create pod.yaml file

apiVersion: v1
kind: Pod
metadata:
  name: hello-world-pod
spec:
  nodeName: 'c1-node1'
  containers:
  - name: hello-world
    image: gcr.io/google-samples/hello-app:1.0
    ports:
    - containerPort: 8080

kubectl apply -f pod.yaml

#Our Pod should be on c1-node1
kubectl get pod -o wide

#Let's delete our pod, since there's no controller it won't get recreated :(
kubectl delete pod hello-world-pod 

#Now let's cordon node1 again
kubectl cordon c1-node1

#And try to recreate our pod
kubectl apply -f pod.yaml

#You can still place a pod on the node since the Pod isn't getting 'scheduled', status is SchedulingDisabled
#Because we have specify the nodeName in the spec and bypass the scheduling process
kubectl get pod -o wide

#Can't remove the unmanaged Pod either since it's not managed by a Controller and won't get restarted in another node
kubectl drain c1-node1 --ignore-daemonsets 

#Let's clean up our demo, delete our pod and uncordon the node
kubectl delete pod hello-world-pod 
 
#Now let's uncordon node1 so it's able to have pods scheduled to it
kubectl uncordon c1-node1

Demo​

Demo