k8s step-by-step installation guide on Ubuntu 20.04 from scratch

k8s-install.md

Certainly! Here's a step-by-step guide to installing Kubernetes (K8s) on Ubuntu 20.04 from scratch. This guide will walk you through the process of setting up a basic Kubernetes cluster using kubeadm, kubelet, and kubectl.

Prerequisites:

1. Ubuntu 20.04: You should have a clean installation of Ubuntu 20.04 on the machines where you plan to set up your Kubernetes cluster.

2. Minimum 2 Nodes: For a basic Kubernetes cluster, you need at least two nodes - one for the master and one or more for worker nodes.

3. Network Configuration: Ensure that your nodes can communicate with each other over the network. You should have a static IP address for each node.

4. Root Privileges: You need to run some commands with root privileges, so make sure you have sudo access.

Step 1: Update and Install Required Packages

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

Step 2: Disable Swap

Kubernetes requires that swap be disabled. You can disable it temporarily with the following command:

sudo swapoff -a

To disable it permanently, edit the /etc/fstab file and comment out the line that references swap:

sudo nano /etc/fstab
# Comment out the line containing swap

Step 3: Install Kubernetes Tools

sudo apt install -y 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 install -y kubelet kubeadm kubectl

Step 4: Initialize the Kubernetes Master Node

On your master node, initialize the Kubernetes cluster using kubeadm. Replace MASTER_IP with the actual IP address of your master node.

sudo kubeadm init --pod-network-cidr=192.168.0.0/16 --apiserver-advertise-address=MASTER_IP

After the initialization is complete, you will see a message with a kubeadm join command to add worker nodes to the cluster. Make sure to save this command for later use.

Step 5: Set Up Kubectl for Your User

Run these commands on your master node to configure kubectl for your user:

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

Step 6: Install a Network Plugin

Choose a network plugin for your cluster. In this example, we'll use Calico:

kubectl apply -f https://docs.projectcalico.org/v3.18/manifests/calico.yaml

Step 7: Join Worker Nodes

On each worker node, run the kubeadm join command you saved from Step 4. It should look something like this:

sudo kubeadm join MASTER_IP:6443 --token TOKEN --discovery-token-ca-cert-hash SHA256_HASH

Step 8: Verify Cluster

Back on the master node, you can check the status of your cluster:

kubectl get nodes

You should see all nodes in the "Ready" state.

Congratulations! You've successfully installed Kubernetes on Ubuntu 20.04 from scratch. You can now deploy and manage containers using Kubernetes.

By Harshhaa Reddy