Multinode cluster setup using kubeadm

Kubeadm is a real-time setup, using which we can set up a multi-node Kubernetes cluster.
It is very popular, and you can have multiple VMs on your machine and configure the Kubernetes master and its node components.
If you have limited resources but want to use Kubeadm, you can use some cloud-based virtual machines.

Launch three instance [Here I have used ubuntu server of t2.medium]

Prerequisites :

1: Check the machines of the cluster can ping each other via ip and hostname
You can change hostname as per this commands.. here I have changed the master and workers hostname

Now paste the ip hostname of three node inside vi /etc/hosts in both master and workers node

You will be able to ping eachother after this.

2: Swap should be off

3: Respective Ports in the firewall should be opened

4: Check for the minimum configuration of the machine from the official documentation

Commands to run on all the nodes [Master and Workers]

Get sudo working

sudo -l

update packages and their version

sudo apt-get update && sudo apt-get upgrade -y

install curl and apt-transport-https

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

add key to verify releases

curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -

add kubernetes apt repo

cat <<EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list
deb https://apt.kubernetes.io/ kubernetes-xenial main
EOF

install kubelet, kubeadm and kubectl

sudo apt-get update

sudo apt-get install -y kubelet kubeadm kubectl

install docker

sudo apt-get install docker.io

apt-mark hold is used so that these packages will not be updated/removed automatically

sudo apt-mark hold kubelet kubeadm kubectl

After the above commands are successfully run on all the worker nodes. Below steps can be followed to initialize the Kubernetes cluster.

On Leader/master Node
Run the below command on the node that you want to make the leader node. Please make sure you replace the correct IP of the node with IP-of-Node

kubeadm init --pod-network-cidr=10.244.0.0/16 -v=9

Now run these 3 commands

Join worker nodes to the Leader node
Once the command kubeadm init is completed on the leader node, below we would get a command like below in the output of kubeadm init that can be run on worker nodes to make them join the leader node.

kubeadm join 206.189.134.39:6443 --token dxxfoj.a2zzwbfrjejzir4h \
    --discovery-token-ca-cert-hash sha256:110e853989c2401b1e54aef6e8ff0393e05f18d531a75ed107cf6c05ca4170eb

Install CNI plugin
The below command can be run on the leader node to install the CNI plugin

kubectl apply -f

https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

kubectl get nodes

Now deploy a ngnix image and expose to port 80 as shown below

Paste the ip in the browser, It will shown your image

You can access this cluster in your personal laptop by setting up opnVpn setup