Kubernetes

Anything about kubernetes

How to setup a validation webhook in Kubernetes?

This post describes how to write and configure a Kubernetes validation webhook in a Kubernetes cluster. The details about “what is a validation webhook” is described here. You can find the code used in this post on this  GitHub page. Pre-requisites: You must have admin privileges in the cluster. Some knowledge of JSON. Some knowledge …

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What is Validation Webhook in Kubernetes

What is a validation webhook in Kubernetes? If you are a Kubernetes administrator or learning the security and administration in the Kubernetes environment, this post is for you. Here, I have described the importance of the webhooks, and their uses, and explained how these webhooks may benefit you in administrating your cluster. The out-of-the-box Kubernetes …

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Enforcing the Container Image Download Behavior in Kubernetes

In this post, we will see a few ways to control and enforce the container image download behavior of Kubernetes(kubelet). We will also see the various examples with different Image Pull policies used. The Default behavior When a pod creation is requested, it will be scheduled on the most suitable node by the Kube-scheduler—the kubelet …

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Automatically create Namespace in Kubernetes

This post will provide the procedure and examples to enable the automatic namespace creation in the Kubernetes cluster. By default, if a user requests an object creation in any non-existing namespace, the request will fail. However, this default behavior of the API-Server(Kubernetes) can be altered by an admission plugin called NamesapceAutoProvision. The Default Behaviour: list …

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Getting custom output from kubectl with examples

One of the most common ways to interact with the Kubernetes Cluster is using the “Kubectl.” By default, in most cases, the output is returned in tabular format, which is good enough for most cases. However, sometimes if you want more control over the produced output, kubectl provides you following formats: kubectl get pod -o …

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How to Check what’s inside the ETCD Database in Kubernetes

If you have worked in the Kubernetes environment, the chances are high that you have heard about ETCD Database. ETCD is typically used in distributed systems as a database; the most famous example is Kubernetes. So typically, you will find ETCD present in the controller nodes of the Kubernetes Cluster. For high Availability configurations, ETCD …

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Scale Nodes in Kubernetes Cluster using Kubespray

This post is will provide steps to add a new node to the Kubernetes cluster using Kubespray.   The below snippet shows the existing node in the cluster, note that I have one master and two worker nodes.  kubectl get node -o wide NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME kube-master Ready control-plane,master …

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Get the Node Resource usage in Kubernetes – no plugin

Resources like CPU, Memory, Disk are critical for the performance of the node and the pods(containers) running on it.  You can read a detailed post about these resources here. In this post, we will cover the commands for printing the resources in a short and meaningful format.  A concise yet meaningful format is helpful for …

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