Kubectl Tricks & Tips I Always Forget

kubectl.md

Kubectl Commands

Node Data

Get a list of pods on for each node based on node status that is unschedulable

for i in $(kubectl get nodes -o wide -L my.label/type --field-selector spec.unschedulable=true |sed 1d | awk '{print $1}'); do
  kubectl get pods --all-namespaces --field-selector spec.nodeName=${i} -o wide
done

Kubectl Config

Set a cluster certificate-authority-data

kubectl config --kubeconfig full_cluster \
  set clusters.${cluster_name}.certificate-authority-data ${data_base64_encoded}

Kubectl Taints

Adding a taint to the master nodes

kubectl taint nodes mynode node-role.kubernetes.io/master=:NoSchedule

or remove

kubectl taint nodes mynode node-role.kubernetes.io/master:NoSchedule-

Storage!

How much storage is flapping in the wind.

kubectl get pv | grep Released | awk '{print $2}' |cut -d"G" -f1 | awk '{total +=$1} END {print "Total:", total, "Gi"}'

Jobs

Start a job from a cronjob. I need this when something fails and I missed the scheduled cron period.

kubectl create job --from=cronjob/my_cronjob_name my_onetime_run_job_name

RBAC

Security is hard, why not make it easier. Install this awesome tool to handle querying your cluster. This works a lot better than parsing a bunch of json.

https://github.com/FairwindsOps/rbac-lookup

Test your changes as a specific user.

kubectl --as=me@abond.dev --as-group=role:admin --as-group=role:engineer get virtualservice

yet another way to test permissions

$ k auth can-i get statefulset/zk --as=system:serviceaccount:jenkins:default -n zookeeper
yes

POD Details

Find those resource limits.

kubectl get po -o=jsonpath="{range .items[*]}{.metadata.namespace}:{.metadata.name}{'\n'}{range .spec.containers[*]}  {.name}{'\n'}    CPU|{.resources.requests.cpu}|{.resources.limits.cpu}{'\n'}    MEM|{.resources.requests.memory}|{.resources.limits.memory}{'\n'}{end}{'\n'}{end}"

Reload Container

When you want to kill just one container

kubectl exec -it mypod -c telegraf -- /bin/kill -SIGHUP 1