• Getting Kubernetes documentation using kubectl

  3 min read

  
  

  While forking on Kubernetes manifest it's easy to forget the available fields for each Kubernetes object. Using kubectl explain we can get all the fields available with a short description of them. Pretty much a man inside kubectl

  13/08/2021

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• Kubernetes: cannot delete Pods with local storage

  2 min read

  
  

  While draining a node it might fail with the message cannot delete Pods with local storage as follows:

  $ kubectl drain tycho.pet2cattle.com --ignore-daemonsets
  node/tycho.pet2cattle.com already cordoned
  error: unable to drain node "tycho.pet2cattle.com", aborting command...
  
  There are pending nodes to be drained:
   tycho.pet2cattle.com
  error: cannot delete Pods with local storage (use --delete-emptydir-data to override): spinnaker-ampa/spin-rosco-658fdb4694-v99jt
  

  02/08/2021

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• tree visualization of Kubernetes objects

  2 min read

  
  

  Some kubernetes objects creates and manages other kubernetes objects in order to provide it's functionality. For example, the Deployment object creates a ReplicaSet that in turn creates the desired Pod objects. We can always track down this relationship using kubectl describe but using the tree krew plugin we can see the relationship in a visual way. We can install it like so:

  $ kubectl krew install tree
  

  14/06/2021

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• kubernetes: Rollback a deployment update

  2 min read

  
  

  When performing rolling updates we can see it's history using kubectl rollout history:

  $ kubectl rollout history deploy pet2cattle
  deployment.apps/pet2cattle 
  REVISION  CHANGE-CAUSE
  100       <none>
  101       <none>
  102       <none>
  103       <none>
  104       <none>
  105       <none>
  106       <none>
  107       <none>
  109       kubectl scale deployment/pet2cattle --replicas=2 --record=true
  110       kubectl scale deployment/pet2cattle --replicas=5 --record=true
  111       kubectl scale deployment/pet2cattle --replicas=1 --record=true
  

  If have any problem with the update we can undo and update using kubectl rollout undo

  25/05/2021

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• How to imperatively change a container's image

  2 min read

  
  

  To change a container's image we can:

  • Update the yaml definition and push it using kubectl apply
  • Use kubectl edit to update it using a definition fetched from the Kubernetes cluster itself
  • To use kubectl set image to set the new image

  Let's check how to use kubectl set image

  14/05/2021

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