Prepare VM for Kubernetes

This section describes how to prepare a virtual machine for kubernetes. This procedure is common for both master and worker nodes.

Install docker runtime

sudo apt update
sudo apt upgrade
sudo apt install docker.io
sudo systemctl start docker
sudo systemctl enable docker

Add your user to the docker group

Adding your user to the docker group allows you to run docker commands without the need to sudo

sudo usermod -aG docker ${USER}

Log out of your shell and log back in.

Check your docker install

docker run hello-world
docker container list --all

You should see the commands completed successfully:

CONTAINER ID   IMAGE         COMMAND    CREATED          STATUS                      PORTS     NAMES
c14e7b3a7c36   hello-world   "/hello"   20 seconds ago   Exited (0) 19 seconds ago             competent_hopper

Install kubernetes tools

Note

In the following commands, we use xenial repository to pull kubernetes binaries and tools. This is not a typo. Focal uses xenial k8s repos.

sudo apt install apt-transport-https curl gnupg2 software-properties-common
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add
sudo apt-add-repository "deb http://apt.kubernetes.io/ kubernetes-xenial main"
sudo apt install kubeadm kubelet kubectl kubernetes-cni

Configure netfilter settings

sudo modprobe overlay
sudo modprobe br_netfilter

sudo tee /etc/sysctl.d/kubernetes.conf<<EOF
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
EOF

sudo sysctl --system

Configure docker drivers

sudo tee /etc/docker/daemon.json<<EOF
{
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "100m"
  },
  "storage-driver": "overlay2"
}
EOF

sudo systemctl daemon-reload
sudo systemctl restart docker

Enable kubelet service

sudo systemctl enable kubelet

Cache kubernetes docker images

sudo kubeadm config images pull