Here, we show as shortly as possible how we can place a POD on the controlplane node on killerkoda CKA playground:
Task: place a POD on the controlplane POD using Affinity
- Find documentation: kubernetes.io –> Documentation –> Search „affinity“
–> you will find: Assign Pods to Nodes using Node Affinity | Kubernetes
# create POD YAML:
k run mypod--image nginx -o yaml --dry-run=client > pod.yaml
# edit pod.yaml (in killerkoda you can use the editor that helps with the syntax. Also look in the documentation above):
apiVersion: v1
kind: Pod
metadata:
labels:
run: mypod
name: mypod
spec:
affinity:
nodeAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
nodeSelectorTerms:
- matchExpressions:
- key: myKey
operator: In
values:
- "label1"
- "label2"
# create pod
k apply -f pod.yaml
# check pod location
k get pod -o wide
# check, why the pod is in Pending state:
k describe pod mypod | grep -A 100 Events:
# add a matching label to the controlplane node
k label nodes controlplane myKey=label1
# the pod is still not scheduled because of a taint. View taints:
k describe nodes controlplane | grep -i taint
# remove taint
k taint node controlplane node-role.kubernetes.io/control-plane:NoSchedule-
# now the pod is scheduled
k get pod -o wide
Reference
- Long ago, we had written quite lengthy blog posts about Node Selectors and various scenarios on how to use Node Affinity and Anti-Affinity:
