This article will guide you how to create a Kubernetes Cluster on VM (Virtual Machines). This configuration is advantageous for establishing a physical Kubernetes cluster on your virtual machines. In this scenario, there will be one Master Node and one Worker Node on separate Ubuntu servers.

Step 1 – Set hostname on each Node

1. Login to Master Node server and set hostname using hostnamectl command

$ sudo hostnamectl set-hostname "k8smaster.example.net"
$ exec bash

2. On the Worker Nodes, run below commands

//This is for 1st Worker node
$ sudo hostnamectl set-hostname "k8sworker1.example.net"

//This is for 2nd Worker node
$ sudo hostnamectl set-hostname "k8sworker2.example.net"
$ exec bash

Step 2 – Map Hostnames to IP Addresses in /etc/hosts file

1. Get Private Ips of the server

$ sudo apt update -y
$ sudo apt install net-tools -y
$ ifconfig

Take private ip address from above command and proceed to next step

2. Open the file using below command

$ sudo nano  /etc/hosts

3 – Add the below entries in opened file ( /etc/hosts) in last step

Example – <Server_private_IP_address>   <hostname1>

192.168.1.xx              k8smaster.example.net k8smaster
192.168.1.xx              k8sworker1.example.net k8sworker1
192.168.1.xx              k8sworker2.example.net k8sworker2

Save & Close the file (/etc/hosts).

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Step 3 – Installing Docker, Kubectl, And Kubeadm Packages

In order to install above packages, follow the steps mentioned below on Master as well as Worker Nodes

1. Disable swap & Add kernel Parameters

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

2. Configure persistent loading of kernel modules

$ sudo tee /etc/modules-load.d/containerd.conf <<EOF
overlay
br_netfilter
EOF

3. Load at runtime

$ sudo modprobe overlay
$ sudo modprobe br_netfilter

4. Update Iptables Settings

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

5. Reload the above changes with below command.

$ sudo sysctl --system

6. Installing docker

$ sudo apt install docker.io -y
$ sudo systemctl start docker
$ sudo systemctl enable docker

7. Add Apt Repository for Kubernetes

$ sudo apt-get update
$ sudo apt-get install -y apt-transport-https ca-certificates curl software-properties-common
$ curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo gpg --dearmour -o /etc/apt/trusted.gpg.d/kubernetes-xenial.gpg
$ sudo apt-add-repository "deb http://apt.kubernetes.io/ kubernetes-xenial main"

8. Install Kubectl, Kubeadm and Kubelet

$ sudo apt update
$ apt list -a kubeadm
$ sudo apt install -y kubeadm kubelet kubectl
$ sudo apt-mark hold kubelet kubeadm kubectl

Step 4 – Follow below steps on Master Node

1. Install Kubernetes Cluster on Ubuntu server

$ sudo kubeadm init

Note: After the initialization is complete, you will see a message with instructions on how to join Worker Nodes to the cluster. Make a note of the kubeadm join command for future reference.

If you forgot the token then use below command (follow below screenshot also) to create a new token.

$ kubeadm token create --print-join-command

2. To start interacting with cluster, run following commands on the Master Node,

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

3. Install Calico Network Plugin (A network plugin is required to enable communication between pods in the cluster)

$ kubectl apply -f https://raw.githubusercontent.com/projectcalico/calico/v3.26.0/manifests/calico.yaml

Step 5 – Follow below steps on Worker Nodes

Join Worker Nodes to the Cluster. On each Worker Node, use the kubeadm join command you noted down earlier after initializing the Master Node

$ sudo kubeadm join 10.5.0.7:6443 --token 2slaav.qpcu7ivjrvs4qe9a --discovery-token-ca-cert-hash sha256:16aa5830fc58f0b46c9327752972d0a015b62f56c3e62857b337d7f94274a319

Now K8 cluster will be installed. Also Master and Worker Node will be communicating with each other.

Step 6 – Verify the Node status (Execute below commands in Master Node only)

$ kubectl get nodes

Step 7 – Verify the status of pods in kube-system namespace (Execute below commands in Master Node only),

$ kubectl get pods -n kube-system

 

You can get in touch with our DevOps Consultants at TechEnhance, and we will help you transition smoothly. If you need more help understanding Kubernetes, book a free call with us anytime!