• Dynamically provisioned PersistentVolumes using StatefulSet

  6 min read

  
  

  The basic idea behind a StatefulSet is to be able to manage stateful workloads on Kubernetes, unlike Deployments, creating a unique identity for each Pod using a common spec.

  With this in mind we might just copy the Pod's template from a Deployment to a StatefulSet object to make it stateful, but it's not always quite that simple.

  21/02/2022

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• What's a Kubernetes Deployment object?

  2 min read

  
  

  Maybe the most common object used for deploying applications on Kubernetes is the Deployment object. It is intended to provide declarative updates for Pods at a controlled rate.

  With a Deployment we are setting the desired state of a ReplicaSet. The Deployment controller will take the appropriate actions to adjust the ReplicaSet so it has the correct amount of Pods

  09/08/2021

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• Kubernetes deployment strategies

  2 min read

  
  

  To update a Deployment objects we can choose between two built-in strategies used to replace old Pods by new ones: Recreate and RollingUpdate

  Let's see the differences between them

  04/08/2021

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• Using an HPA object to autoscale a deployment based on it's Pods CPU metrics

  3 min read

  
  

  On Kubernetes, scaling an application is just a matter of defining how many replicas we want:

  $ kubectl scale deployment/demo --replicas=5
  deployment.apps/demo scaled
  

  Having to manually adjust the number of replicas is not really practical. Here's where the HorizontalPodAutoscaler (HPA) comes into play

  01/07/2021

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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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