dockerdummy

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Enable User Namespaces in Kubernetes

This guide walks you through enabling user namespaces in Kubernetes, allowing containers to run as root inside the pod while being mapped to a non-root user on the host. This enhances isolation and security, and makes it possible to allow users more freedom—without the usual risk. Tested with: Ubuntu 24.04 Kubeadm 1.32.3 CRI-O 1.32 Calico 3.29.3 For full reference, see the official Kubernetes…

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How to create a single Node Kubernetes Cluster with dual stack IPv4/IPv6 Support with CRI-O and Calico

In this blog post, I have summarized how I have set up a single-node Kubernetes cluster version 1.32 on a fresh Ubuntu 24.04 with dual stack IPv4/IPv6 support. Tested with: Ubuntu 24.04 Kubeadm 1.32.3 CRI-O 1.32 Calico 3.29.3 Step 1: Update the system sudo apt-get update && sudo apt-get upgrade -y Step 2: Disable Swap sudo swapoff -a sudo sed -i '/swap/d' /etc/fstab Step 3: Install required…

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Kubernetes Cheat Sheet: Switching from Containerd to CRI-O Made Easy

Why Replace Containerd with CRI-O in Kubernetes? Switching container runtimes again might seem unnecessary after the recent move from Docker to containerd. However, CRI-O offers unique features like enhanced Kubernetes compatibility and improved security. For example, I used CRI-O to test Kubernetes user namespaces on an existing Kubernetes 1.32 installation (Ubuntu 24.04). These namespaces help…

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Create a Next.js App and Convert It to the App Router with Cursor AI

We will show how to create a Next.js example app and convert it to the app router with the help of the Cursor AI composer. We will also extend the code by adding a new card pointing to this blog post. Step 1: Sign into vocon cloud and start Cursor AI Go to cloud.vocon-it.com/products and click the button in the Cursor AI card. Sign in or log into vocon cloud via Google or GitHub (recommended).…

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Kubernetes InPlacePodVerticalScaling Feature: Changing CPU and Memory Reservations and Limits without POD Restart

In Kubernetes v1.27, the InPlacePodVerticalScaling feature was introduced as an alpha capability, allowing you to adjust CPU and memory resources of running pods without restarting them. This feature can reduce downtime and make resource scaling more efficient. In this guide, we’ll explore how to test this feature on Killerkoda, a free Kubernetes playground for hands-on…

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Cheat Sheet: How to install Kubernetes via kubadm on Ubuntu 24.04 (and trying to join it as an additional master to an existing cluster)

ChatGPT helped in this task, but some commands did not work immediately, so I had to ask ChatCPT how to fix the errors I encountered. The command presented here leads through the process of installing Kubernetes using kubeadm on a fresh Ubuntu 24.04 system without any errors (as long as the world does not change too much). Step 1: Install kubeadm, kubelet and kubectl MAJOR_VERSION=1.26 # Add GPG…

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Kubernetes horizontal POD Autoscaling - Hello World

For a quick test of horizontal autoscaling of an NginX deployment, we need the following ingredients: a metrics server installation to be able to measure the POD’s CPU an nginx deployment with a CPU reservation an auto scaler configuration a process that causes high CPU This can be tested on: https://killercoda.com/playgrounds/scenario/kubernetes Install Metrics (quick&insecure way) curl -s -L…

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How I earned the Certified Kubernetes Administrator (CKA) badge - what would I do differently today?

What is the CKA? The Certified Kubernetes Administrator (CKA) certification proves you have hands-on experience managing Kubernetes clusters. How did I learn Kubernetes? Three years ago, I purchased a 4-day classroom Kubernetes Administration course (LFS458) from FastLane. It was not cheap, but FastLane has provided us with a good trainer. It was worth it. After I had taken the classroom…

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Linux Root Terminal on vocon Cloud - How to save your Image and re-launch a Container based on that Image

Linux Root Terminal on vocon Cloud - How to save your Image and re-launch a Container based on that Image

This blog post shows how you can run and manage your Docker images on vocon Cloud Desktop. We will launch an Ubuntu container, install git software as a root user and create and save the resulting Docker image on Docker Hub. Then we launch a Linux container based on the new Docker image. Step 1: Launch an Ubuntu Terminal on vocon Cloud vocon Cloud offers Linux environments running in your…

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Creating a StoryBook Hello World @ NextJS with the help of OpenAI based on ChatGPT - Part 1: chatting and creating a new Next.js app

Do we still need blogs, if there is ChatGPT around? I will test the OpenAI version of ChatGPT. In the long run, we intend to create a NextJS Hello World program with StoryBook. In this part, we will start chatting with OpenAI and we will create a new Next.js app by following its suggestions. Step 1: Sign in to ChatGPT @ OpenAI Go to https://chat.openai.com/chat and sign in. Step 2: Ask for a…

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Kubernetes Task: assign a POD to a Node via Node Affinity - Cheat Sheet

Kubernetes Task: assign a POD to a Node via Node Affinity – Cheat Sheet

Here, we show as shortly as possible how we can place a POD on the controlplane node the on killerkoda CKA playground: Task: place a POD on the controlplane POD using Affinity Find documentation: kubernetes.io –> Documentation –> Search “affinity” –> you will find: Assign Pods to Nodes using Node Affinity | Kubernetes # create POD YAML: k run mypod--image nginx -o yaml --dry-run=client >…

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Kubernetes etcd backup and restore - cheat sheet

Kubernetes etcd backup and restore – cheat sheet

This is a cheat sheet on how to perform backup&restore of the etcd server in kubernetes quickly. Test this on Killercoda Play with Kubernetes tl;dr Find reference: https://kubernetes.io –> Documentation –> Search “etcd backup restore” –> you will find: Operating etcd clusters for Kubernetes | Kubernetes # get params cat /var/lib/kubelet/config.yaml | grep static cat…

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Playwright Hello World @Angular14

Playwright Hello World @Angular14

In this step-by-step guide, we will show you how to create your first successful Playwright test for an Angular 14 project. Step 0 (optional): Start Cloud Desktop – or use your own environment If you need a development environment, you can connect to our Developer’s Cloud Desktop. Simply click on the image below and launch the environment by clicking on the WebStorm Cloud Desktop button (bring…

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Cheat Sheet: Install non-privileged podman v3 in a CentOS 7 Container

Cheat Sheet: Install non-privileged podman v3 in a CentOS 7 Container

See how you can run a user space podman container inside another non-privileged container. For that, we create a CentOS 7 image with podman v3 installed. We spin up a Kubernetes non-privileged container from this image, and we show that we are able to run other podman containers successfully. Tested on Kubernetes v1.22.9 with CentOS 7 Kubernetes agents and containerd container runtime…

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How to enter a root shell session to a container without Docker - replace 'docker exec' by 'runc'

How to enter a root shell session to a container without Docker – replace ‘docker exec’ by ‘runc’

The latest version of Kubernetes does not support Docker as a container runtime anymore. That is why many Kubernetes administrators have migrated their cluster’s container runtime from docker to another container runtime like containerd or cri-o. Or they will do that soon. References https://gist.github.com/mamiu/4944e10305bc1c3af84946b33237b0e9 Old: entering a Container as root with…

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[SOLVED] WebStorm@CentOS Bug: Could not initialize class com.intellij.javascript.debugger.console.jcef.JCE

I guess you have encountered the following error message if you have found here: Error running 'Angular Application' # <- the name of the Debug Profile might be named differently in your case Could not initialize class com.intellij.javascript.debugger.console.jcef.JCE This happened to us on our WebStorm Cloud Desktop Service. It occurs on CentOS systems when you try to debug your application on…

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Upgrade Kubernetes Cluster - Cheat sheet

Upgrade Kubernetes Cluster – Cheat sheet

This is a cheat sheet created during the last upgrade of a Kubernetes cluster serving Developer’s Cloud Desktops to our customers. TLDR; style. Create  Backup Recommended Upgrade to the latest Hotfix Version This is an example of how to upgrade to v1.21.12 as the latest hotfix version of v1..21: # upgrade DEV v1.21.3 to v1.21.12: sudo yum install -y kubeadm-1.21.12-0 --disableexcludes=kubernetes…