Kubectl snippet

Info

Small script and take a note to interact between kubectl and your kubernetes cluster.

You can explore command with kubectl in some place, including

• kubectl Quick Reference
• kubectl reference

Helpful command

Get base64 decode of secret with no more 3th party

kubectl get secrets -n <namespace> <secret> -o go-template='{{range $k,$v := .data}}{{"### "}}{{$k}}{{"\n"}}{{$v|base64decode}}{{"\n\n"}}{{end}}'

Debug your node via kubectl

kubectl debug node/my-node -it --image=<img>

Check the resource of workload with resource-capacity extension

Download via krew, find out the step at krew installing

# Extension: https://github.com/robscott/kube-capacity
 
# Check the available resources
kubectl resource-capacity -a
 
# Check detail resource utilize of all workload
kubectl resource-capacity -p --util

Scale down the statefulset application

# Use scale option
kubectl scale --replicas=0 sts <sts name>
 
# Or we can use patch or edit option
kubectl patch statefulsets <stateful-set-name> -p '{"spec":{"replicas":<new-replicas>}}'

You need to consider when apply scaling down can not working because “cannot scale down a StatefulSet when any of the stateful Pods it manages is unhealthy. Scaling down only takes place after those stateful Pods become running and ready.” . Read more in: Scale a StatefulSet

Delete pods with not on state Running

k delete pods -n <name-space> --field-selector=status.phase!=Running

Create the generic secrets from file, for example binary file with auto convert to base64 format

kubectl create secret generic accounts-identityserver-certificate --from-file=certificate.pfx --dry-run=client -o yaml > certificate_sec.yaml 

Check currently config context

kubectl config view --minify

Change default storage class for your node

kubectl patch storageclass <sc-specific> -p '{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"true"}}}'