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README.md

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+# scripts to deploy / upgrade Kubernetes lab clusters on Ubuntu
+
+### I use Ubuntu (Server 20.04) in order to make use of up-to-date cluster and kernel packages.
+
+# ASSUMPTIONS
+- 2+ available role-dedicated lab nodes (ideally 1 master and 2+ workers) running Ubuntu (I use 4 (1+3) KVM guest domains created via libvirt, YMMV)
+- SSH access to all nodes with pubkey auth
+- sudo as root without password
+- variables named <i>K8S_VERSION_*</i> sent and accepted via SSH
+- one doesn't know Ansible (half-joking there, this is more of an educational, "quick 'n' dirty" effort)
+- one knows there are other, possibly better ways
+
+# INSTALLATION
+ssh master1 bash -xs < k8s-ubuntu-install<br>
+ssh worker1 bash -xs < k8s-ubuntu-install
+
+## generic installation procedure
+- kubeadm init on <strong>master1</strong>
+- kubeadm join on <strong>worker1</strong>
+
+# UPGRADE
+## when upgrading point releases
+export K8S_VERSION_CURRENT=$(kc version --short | awk '/^Server/{print substr($3,2)}')<br>
+export K8S_VERSION_LATEST=$(curl -sL https://dl.k8s.io/release/stable-${K8S_VERSION_CURRENT%.*}.txt)
+
+## otherwise
+export K8S_VERSION_MAJOR=1<br>
+export K8S_VERSION_LATEST=$(curl -sL https://dl.k8s.io/release/stable-${K8S_VERSION_MAJOR}.txt)
+
+### control plane first
+kubectl drain master1 --ignore-daemonsets --delete-local-data<br>
+ssh master1 sudo apt update
+
+### when upgrading the OS
+ssh master1 bash -xs < k8s-ubuntu-update-os
+
+### otherwise
+ssh master1 bash -xs < k8s-ubuntu-update-master<br>
+kubectl uncordon master1<br>
+sleep 60<br>
+ssh master1 sudo docker image prune -af
+
+### workload plane, workers one by one
+kubectl drain worker1 --ignore-daemonsets --delete-local-data<br>
+ssh worker1 sudo apt update
+
+### when upgrading the OS
+ssh worker1 bash -xs < k8s-ubuntu-update-os
+
+### otherwise
+ssh worker1 bash -xs < k8s-ubuntu-update-worker<br>
+kubectl uncordon worker1<br>
+sleep 60<br>
+ssh worker1 sudo docker image prune -af

k8s-ubuntu-install

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+sudo apt-get update && sudo apt-get install -y apt-transport-https curl
+curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
+cat <<EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list
+deb https://apt.kubernetes.io/ kubernetes-xenial main
+EOF
+sudo apt-get update
+sudo apt-get install -y kube{let,adm,ctl} docker.io
+sudo apt-mark hold kube{let,adm,ctl,rnetes-cni}
+sudo systemctl enable --now docker
+sudo gpasswd -a ubuntu docker

k8s-ubuntu-update-master

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+if [ ${K8S_VERSION_CURRENT:-v0.0.0} = ${K8S_VERSION_LATEST#v} ];
+	then
+		echo nothing to do
+		exit 0
+fi
+
+sudo apt install -y kubeadm=${K8S_VERSION_LATEST#v}-00
+sudo kubeadm upgrade apply -y ${K8S_VERSION_LATEST}
+sudo apt install -y kube{let,ctl}=${K8S_VERSION_LATEST#v}-00
+sudo apt autoremove -y
+sudo apt autoclean
+sudo journalctl --vacuum-time=3d
+#sudo docker image prune -af
+

k8s-ubuntu-update-os

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+sudo apt-mark hold kube{adm,let,ctl,rnetes-cni}
+sudo apt upgrade -y
+sudo apt-mark unhold kube{adm,let,ctl,rnetes-cni}
+sudo shutdown -r now
+

k8s-ubuntu-update-worker

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+if [ ${K8S_VERSION_CURRENT:-v0.0.0} = ${K8S_VERSION_LATEST#v} ];
+	then
+		echo nothing to do
+		exit 0
+fi
+
+sudo apt install -y kubeadm=${K8S_VERSION_LATEST#v}-00
+sudo kubeadm upgrade node
+sudo apt install -y kube{let,ctl}=${K8S_VERSION_LATEST#v}-00
+sudo apt autoremove -y
+sudo apt autoclean
+sudo journalctl --vacuum-time=3d
+#sudo docker image prune -af