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K8s at Hosttech

K8s at Hosttech published on

This how-to documents how to set up a K8s cluster at hosttech.

Base setup Ubuntu VMs

There are two VMS:

  • saanen.chloesoe.ch
  • lauenen.chloesoe.ch

Via https://www.myhosttech.eu/user-products/ it's possible to re-install the operating system.

Configure after re-install:

  • vigr and add user to sudo group
  • visudo and ensure 
    %sudo   ALL=(ALL:ALL) NOPASSWD: ALL
  • Set hostname
    • /etc/hosts 127.0.1.1 xyz.chloesoe.ch xyz
    • hostnamectl set-hostname xyz.chloesoe.ch
  • update-alternatives --config editor
  • enable bash completion in interactive shells in /etc/bash.bashrc
  • ~/.vimrc 
    set laststatus=2
set hlsearch
set backup
set backupdir=~/.vim/tmp,/tmp,~/
set history=5000
  • ~/.bashrc
    • alias ls='ls --color --group-directories-first'
  • /etc/ssh/sshd_conf
    • PasswordAuthentication no
    • PermitRootLogin no
  • copy your key to ~/.ssh/authorized_keys
  • echo "source <(kubectl completion bash)" >> ~/.bashrc

Install K8s

See https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/
Commands from acould.guru course and adjusted where needed.

On all nodes, set up containerd. You will need to load some kernel modules and modify some system settings as part of this
process:

cat << EOF | sudo tee /etc/modules-load.d/containerd.conf
overlay
br_netfilter
EOF
sudo modprobe overlay
sudo modprobe br_netfilter
cat <<EOF | sudo tee /etc/sysctl.d/99-kubernetes-cri.conf
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward
= 1
net.bridge.bridge-nf-call-ip6tables = 1
EOF
sudo sysctl --system

Install and configure containerd.

sudo apt-get update && sudo apt-get install -y containerd
sudo mkdir -p /etc/containerd
sudo containerd config default | sudo tee /etc/containerd/config.toml
sudo systemctl restart containerd

Disable swap on all nodes:

On all nodes, disable swap.
sudo swapoff -a
sudo sed -i '/ swap / s/^\(.*\)$/#\1/g' /etc/fstab

On all nodes, install kubeadm, kubelet, and kubectl.

sudo apt-get update && sudo apt-get install -y apt-transport-https curl gnupg2

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

export kversion=1.23.1-00
sudo apt install -y kubelet=$kversion kubeadm=$kversion kubectl=$kversion

sudo apt-mark hold kubelet kubeadm kubectl

only control-plane

sudo kubeadm init --pod-network-cidr 192.168.0.0/16 --kubernetes-version 1.23.1

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 is working.

kubectl get nodes

Install the Calico network add-on.

kubectl apply -f https://docs.projectcalico.org/manifests/calico.yaml

Get join command for worker node:

kubeadm token create --print-join-command

Worker node

sudo kubeadm join 213.xxx.yyy.zzz:6443 --token <hash> --discovery-token-ca-cert-hash sha256:<shahash>

after joining

Label worker nodes:

kubectl label node lauenen.chloesoe.ch node-role.kubernetes.io/worker=worker

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