INTRODUCTION

In this blog we will see how to setup a Kubernetes cluster for V-1.28 with Kubeadm as agent. This blog will explain detail setup of k8's cluster with step-by-step process. we know that from V-1.24 docker as container runtime has been depreciated, so we have to follow as per Kubernetes official documentation to install container run time.

STEP-1 : Create virtual machines and login into those ( ex - AWS EC2)

Here, first create virtual machines, for example if you are into any public cloud like AWS, launch multiple instances as per your requirement and login to those machines. keep one of the machine as master and others as nodes.

Command to login through SSH

ssh -i "example.pem"ubuntu@ip.compute.amazonaws.com

STEP-2: Update packages

Once we login to our virtual machines, we have to update packages which will be a good practice.

sudo apt update -y

Now, we have to login as root user for sudo privileges, simultaneously disable firewall and swap

On both master and node

Login as root user

sudo su -

Perform all the commands as root user unless otherwise specified

Disable Firewall

ufw disable

Disable swap

swapoff -a; sed -i '/swap/d' /etc/fstab

STEP-3: Install packages

Before setting up our K8's cluster we have install all the dependencies like packages and configs to enable our cluster properly. so run all these commands in all machines including master and nodes.

3.1 - Create a configuration file for Containerd

We’ll begin by creating a configuration file for Containerd, a container runtime that Kubernetes uses. This file defines the modules required by Containerd.

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

3.2 - Load the modules for Networking

Next, we load the required kernel modules for Overlay and Bridge networking.

modprobe overlay
modprobe br_netfilter

3.3 - Set System Configurations for Kubernetes Networking

We set some sysctl configurations to ensure proper networking for Kubernetes.

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

Apply the new settings:

sysctl --system

3.4 Install Containerd

Lets now install containerd for V-1.28

#Install dependencies
apt install -y curl gnupg software-properties-common apt-transport-https ca-certificates

#Enable docker repo
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmour -o /etc/apt/trusted.gpg.d/docker.gpg
add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"

#install containerd
apt-get update && sudo apt-get install -y containerd.io

3.5 Create the Default Configuration File for Containerd

We configure containerd so that it starts using systemd as cgroup

containerd config default | sudo tee /etc/containerd/config.toml >/dev/null 2>&1
sudo sed -i 's/SystemdCgroup \= false/SystemdCgroup \= true/g' /etc/containerd/config.toml

3.6 Restart and Enable Containerd and check status

Now, we will restart and enable containerd

systemctl restart containerd
systemctl enable containerd
systemctl status containerd

3.7 Update Dependency Packages

Update the apt package index and install packages needed to use the Kubernetes apt repository:

sudo apt-get update 
# apt-transport-https may be a dummy package; if so, you can skip that package
sudo apt-get install -y apt-transport-https curl gpg

3.8 Download the public signing key for the Kubernetes package repositories

The same signing key is used for all repositories so you can disregard the version in the URL

curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.28/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg

3.9 Add the appropriate Kubernetes apt repo

# This overwrites any existing configuratiKubernetes apt repositoryon in /etc/apt/sources.list.d/kubernetes.list
echo 'deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.28/deb/ /' | sudo tee /etc/apt/sources.list.d/kubernetes.list

3.10 Update the apt package index, install kubelet, kubeadm and kubectl, and pin their version

sudo apt-get update

FYI - In releases older than Debian 12 and Ubuntu 22.04,/etc/apt/keyringsdoes not exist by default; you can create it by runningsudo mkdir -m 755 /etc/apt/keyrings

3.11 Install K8's packages and turnoff automatic updates

sudo apt-get install -y kubelet=1.28.0-00 kubeadm=1.28.0-00 kubectl=1.28.0-00
sudo apt-mark hold kubelet kubeadm kubectl

STEP-4 Initialize the Cluster

Now that we have all the prerequisites in place, it’s time to initialize the Kubernetes cluster on the control plane node using kubeadm.

FYI - Run this commands only on master machine

kubeadm init --apiserver-advertise-address=master@ip --pod-network-cidr=192.168.0.0/16  --ignore-preflight-errors=all

4.1 Deploy Calico network

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

4.2 Set kubectl Access

To interact with the cluster, we need to configure kubectl. Create the .kube directory, copy the admin configuration, and adjust permissions.

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

4.3 Run cluster join command

kubeadm token create --print-join-command

4.4 Join the nodes machines into cluster

After running the token create command, now copy the token or output of the above command and run it in the node machines

Example token looks like this,

kubeadm join 172.31.2.76:6443 --token 248gw3.4ok7mzcwuzib9n3r 
--discovery-token-ca-cert-hash sha256:0c94a1c49d7fa5884810b2367f0d3f48063f8170f91643690a883ce0d07d1a0d

STEP-5 Verifying the cluster (On master)

kubectl get nodes

Get component status

kubectl get cs