First create 3 virtual machines using Oracle Virtual Box or VMWare Workstation

Each VM should be configured with
RAM         4GB
CPU 2vCPU
HDD         20 GB
NIC Card 1 
OS Ubuntu 20.04

Software requirements
Docker/ContainerD as Container Runtime
Ubuntu 20.04


sudo apt update
sudo apt -y install curl apt-transport-https
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
echo "deb https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list
sudo apt update
sudo apt -y install vim git curl wget kubelet kubeadm kubectl
sudo apt-mark hold kubelet kubeadm kubectl
sudo swapoff -a
sudo mount -a
free -h

# Enable kernel modules
sudo modprobe overlay
sudo modprobe br_netfilter

# Add some settings to sysctl
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

# Reload sysctl
sudo sysctl --system

# Configure persistent loading of modules
sudo tee /etc/modules-load.d/containerd.conf <<EOF
overlay
br_netfilter
EOF

# Load at runtime
sudo modprobe overlay
sudo modprobe br_netfilter

# Ensure sysctl params are set
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

# Reload configs
sudo sysctl --system

# Install required packages
sudo apt install -y curl gnupg2 software-properties-common apt-transport-https ca-certificates

# Add Docker repo
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"

# Install containerd
sudo apt update
sudo apt install -y containerd.io

# Configure containerd and start service
sudo su -
mkdir -p /etc/containerd
containerd config default>/etc/containerd/config.toml

# restart containerd
sudo systemctl restart containerd
sudo systemctl enable containerd
systemctl status  containerd

lsmod | grep br_netfilter
br_netfilter           22256  0 
bridge                151336  2 br_netfilter,ebtable_broute

sudo systemctl enable kubelet

sudo kubeadm config images pull

sudo nano /etc/hosts

Run the following command only on master node. 

sudo kubeadm init   --pod-network-cidr=10.244.0.0/16   --cri-socket unix:///run/containerd/containerd.sock   --upload-certs   --control-plane-endpoint=master01.nextopsvideos.com

Copy below output from above command

mkdir -p $HOME/.kube
sudo cp -f /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

Join the worker nodes using below command

kubeadm join k8s-cluster.computingforgeeks.com:6443 \
  --token sr4l2l.2kvot0pfalh5o4ik \
  --discovery-token-ca-cert-hash sha256:c692fb047e15883b575bd6710779dc2c5af8073f7cab460abd181fd3ddb29a18


Test you cluster by applying following pod definition
kubectl apply -f https://k8s.io/examples/pods/simple-pod.yaml