Kubernetes Cluster Setup in Laptop Using VirtualBox

Download VirtualBox: https://www.virtualbox.org/wiki/Downloads
Download Ubuntu 20.04.3 LTS: https://ubuntu.com/download/desktop/thank-you?version=20.04.3&architecture=amd64
Install Ubuntu three times so that we will have 3 nodes for Kubernetes cluster. One Master node and other two as worker nodes.
Create a NAT Network in Virtual Box (e.g. “Kubernetes Network”) from Network preferences section. Use Network CIDR as 10.0.2.0/24

Attach NAT network to all three instances

Set the hostnames of VMs as following:

sudo hostnamectl set-hostname k8s-control for Master node

sudo hostnamectl set-hostname k8s-worker1 for Worker node 1

sudo hostnamectl set-hostname k8s-worker2 for Worker node 2

Edit /etc/hosts file to include IPs of all three nodes. For e.g.

10.0.2.4 k8s-worker1
10.0.2.15 k8s-control
10.0.2.5  k8s-worker2

Run Following Commands in each of the nodes

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 on all nodes

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 three nodes

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

Install kubeadm, kubelet, and kubectl on all nodes

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 kubelet=1.21.0-00 kubeadm=1.21.0-00 kubectl=1.21.0-00
sudo apt-mark hold kubelet kubeadm kubectl

Initialize pod network, create cluster and setup Kubectl access – On the control plane (master) node only

sudo kubeadm init --pod-network-cidr 192.168.0.0/16 --kubernetes-version 1.21.0
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
kubectl get nodes

Install the Calico network add-on.

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

Get the join command (this command is also printed during kubeadm init), You can copy that too.

kubeadm token create --print-join-command

Copy the join command from the control plane node. Run it on each worker node as root (i.e. with sudo ).

On the control plane (master) node, verify that all nodes in the cluster are ready. Note that it may take a few moments for all of the nodes to enter the READY state.