Kubectl

Introduction The Certified Kubernetes Application Developer (CKAD) exam is a hands-on, command-line-heavy challenge that tests your ability to design, build, and deploy applications in Kubernetes - all while racing the clock. I recently took the CKAD and passed with an overall score of around 82%. Not perfect - but let’s be honest, in a terminal-only, time-boxed environment, "running" is the new "succeeding" 😄. This article collects the practical snippets, workflows, and quick references I used during my preparation. ...

Goals Install kubeadm, kubectl and kubelet on Debian-based Linux Freeze their versions to avoid automatic updates Installation curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add - (1) cat << EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list (2) deb https://apt.kubernetes.io/ kubernetes-xenial main EOF sudo apt-get update (3) sudo apt-get install -y kubelet=1.15.7-00 kubeadm=1.15.7-00 kubectl=1.15.7-00 (4) sudo apt-mark hold kubelet kubeadm kubectl (5) 1 Add the GPG key 2 Add the kubernetes repo to the sources list 3 Update the index 4 Install kubelet, kubeadm and kubectl It’s important to use the same version for kubelet, kubeadm and kubectl. ...

Goals Setup a kubernetes master node on a Linux machine Setup Initialize the cluster on the master node sudo kubeadm init --pod-network-cidr=10.244.0.0/16 This might take a few minutes …​ afterward we set up our local kubeconfig: mkdir -p $HOME/.kube sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config sudo chown $(id -u):$(id -g) $HOME/.kube/config Verify the Cluster Setup Shows that the cluster is responding and kubectl working: kubectl version

Rerun existing completed Job kubectl replace deletes the old job, if there is any error, your job definition is lost, don’t forget to save it first! Replace an existing Job with itself kubectl get job JOBNAME -o yaml | kubectl replace --force -f - Sometimes there are errors importing the job template due to auto-generated labels or selectors .. a quick and dirty hack is to filter them out using jq ...