Cheat Sheet

Update StatefulSet volumeClaimTemplates And Other Uneditable Sections¶

1. Get the latest YAML of the StatefulSet you want to update (e.g., change size of a volumeClaimTemplates entry).
2. Make the changes to the YAML file.
3. Run kubectl delete statefulset STATEFULSET_NAME --cascade=orphan
4. The important thing here is the --cascade=orphan flag, it stops the ControllerRevisions objects (+ the Pods) to not be deleted (no downtime).
5. Now just apply your StatefulSet YAML and if needed trigger a rolling update of the StatefulSet using the kubectl rollout restart statefulset STATEFULSET_NAME command.

Quickly trigger Rolling Update of Deployment, StatefulSet, DaemonSet, etc¶

New Way¶

Example for StatefulSet and Deployment below:

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kubectl rollout restart statefulset STATEFULSET_NAME
kubectl rollout restart deployment DEPLOYMENT_NAME

Old Way¶

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kubectl patch -n kube-system ds kube-proxy -p "{\"spec\":{\"template\":{\"metadata\":{\"annotations\":{\"date\":\"$(date +'%s')\"}}}}}"

Running kubectl replace/kubectl apply on an object which the command above was used on, will always trigger a rolling update again. This is due to the change to the annotations.

Debug Pod manifest to "escape" to the node¶

The Pods manifest assumes that you are allowed to run privileged Pods in your cluster.
If you are using you may need to set a ServiceAccount which is allowed "all the things" (e.g. privileged, hostNetwork, and so on).

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kind: Pod
apiVersion: v1
metadata:
  name: debug-pod
  labels:
    app: debug
spec:
  hostNetwork: true
  tolerations:
    - key: node-role.kubernetes.io/master
      effect: NoSchedule
    - key: "CriticalAddonsOnly"
      operator: "Exists"
  restartPolicy: Never
  hostIPC: true
  hostPID: true
#  nodeName: SPECIFIC_TARGET_NODE
  priorityClassName: "system-cluster-critical"
  containers:
  - name: debug-pod
    image: busybox
    command: ["/bin/sleep", "36000"]
    securityContext:
      privileged: true
      allowPrivilegeEscalation: true

kubectl exec -it POD_NAME -- sh into the Pod and use nsenter to escape the container's namespace:

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$ nsenter -t 1 -m -u -n -i sh

Role Label for Node objects¶

The node-role.kubernetes.io/ can take "anything" as a role.
Meaning that node-role.kubernetes.io/my-cool-role (any value) will cause the kubectl get nodes output to display my-cool-role (and other such role labels) as the Node role.

kubectl: Config/ Context Switching¶

Set Namespace For Current Context¶

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kubectl config set-context --current --namespace NAMESPACE

Switch To Other Context¶

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kubectl config use-context CONTEXT_NAME

Show Contexts¶

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kubectl config get-contexts

Trigger/ Run A CronJob Now (Manually)¶

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kubectl create job --from=cronjob/CRONJOB_NAME JOB_NAME
kubectl create job --from=cronjob/curator curator-manual-run