Kubernetes (k8s) step-by-step installation guide on Ubuntu 20.04/22.04/24.04 from scratch

Step 1: Update Your System

Update the package list and upgrade installed packages:

sudo apt update && sudo apt upgrade -y
sudo reboot

Step 2: Install Dependencies

Install required tools and packages:

sudo apt install -y apt-transport-https ca-certificates curl gnupg lsb-release

Step 3: Disable Swap

Kubernetes requires swap to be disabled:

sudo swapoff -a
sudo sed -i '/ swap / s/^/#/' /etc/fstab

Step 4: Install Docker or containerd

Kubernetes needs a container runtime. We'll use containerd (recommended).

4.1: Install containerd

sudo apt install -y containerd

4.2: Configure containerd

Generate the default configuration file:

sudo mkdir -p /etc/containerd
sudo containerd config default | sudo tee /etc/containerd/config.toml

Restart containerd:

sudo systemctl restart containerd
sudo systemctl enable containerd

Step 5: Install Kubernetes Components

Install kubeadm, kubelet, and kubectl.

5.1: Add the Kubernetes APT repository

curl -fsSL 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

5.2: Install kubeadm, kubelet, and kubectl

sudo apt install -y kubelet kubeadm kubectl
sudo apt-mark hold kubelet kubeadm kubectl

Step 6: Initialize the Kubernetes Cluster

Run the following command on the master node:

sudo kubeadm init --pod-network-cidr=192.168.0.0/16

6.1: Configure kubectl for the current user

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

6.2: Save the Join Command

The output of kubeadm init will include a kubeadm join command for worker nodes. Save this for later.

Step 7: Install a Pod Network Add-On

Choose a CNI (Container Network Interface). We'll use Calico.

7.1: Apply the Calico manifest

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

Step 8: Add Worker Nodes

Run the kubeadm join command from Step 6.2 on each worker node:

sudo kubeadm join <master-ip>:6443 --token <token> \
    --discovery-token-ca-cert-hash sha256:<hash>

Step 9: Verify the Cluster

9.1: Check Nodes

On the master node, check the status of nodes:

kubectl get nodes

9.2: Check Pods

Verify that the cluster is working by checking pods in the kube-system namespace:

kubectl get pods -n kube-system

Optional: Enable Autocompletion for kubectl

sudo apt install -y bash-completion
echo 'source <(kubectl completion bash)' >>~/.bashrc
source ~/.bashrc

Troubleshooting Tips

Reset the Cluster
If the installation fails, reset kubeadm and try again:
```
sudo kubeadm reset -f
sudo rm -rf $HOME/.kube
```

Check Logs
Use the following commands to troubleshoot issues:

journalctl -xeu kubelet
kubectl describe pod <pod-name> -n kube-system

This guide provides a basic Kubernetes cluster installation. For production, consider high-availability setups, security configurations, and monitoring tools. Let me know if you'd like additional details!

NotHarshhaa/k8s-install.md