• What's a kubernetes DaemonSet?

  2 min read

  
  

  When it comes to kubernetes objects, maybe the one that is quite common but still causes a lot of confusion is the DaemonSet. What's it's function?

  04/06/2021

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• tail multiple kubernetes pods

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  While debugging issues we might need to be able to see the output from multiple pods (or multiple) at the same time to be able to understand how they are interacting. Stern allows you to tail multiple pods on Kubernetes and even multiple containers within the pod

  03/06/2021

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• kubernetes: enforce resource limits using LimitRange

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  If we want to make sure the resources for a given namespace are controlled yet we want to be able to give full control to whoever is creating objects in that namespace, we can use LimitRange to enforce some resource constraints:

  • We can enforce a minimum and maximum (and it's default value) for compute resources per Pod or Container or storage request per PersistentVolumeClaim in the namespace
  • We can also enfornce a ratio between request and limit for a resource (so that we are not abusing the control setting limits that are too wide) Set default request/limit for compute resources in a namespace and automatically inject them to Containers at runtime.

  This is implemented as an admission controller that observes the incoming requests and makes sure that it does not violate any of the constraints enumerated in the LimitRange object within it's namespace.

  02/06/2021

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• kubernetes: pod restart policy

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  When defining objects that contain a pod template (such a Deployment or a Job) but also when defining a plain pod we can control under which circumstances a pod will be restarted

  The container restart policy can be controlled using restartPolicy on the spec at the same level where we define the containers:

  apiVersion: batch/v1
  kind: Job
  metadata:
    name: demo-restartPolicy-job
  spec:
    backoffLimit: 2
    template:
      metadata:
        name: demo-restartPolicy-pod
      spec:
        containers:
        - name: demo
          image: sonarsource/sonar-scanner-cli
        restartPolicy: Never  
  

  01/06/2021

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• psql: Get the time it took a query to complete

  1 min read

  If you need to known the amount of time it took a query to complete on PostgreSQL, you can use the \timing function that psql has

  31/05/2021

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