Kubernetes Cluster Setup: Step-by-Step Process

Prerequisite:

• One master (Control Plane) Node

• Two or more servers for worker Node

• 2 GB or more of RAM per machine

• 2 CPUs or more for control plane machines

• Full network connectivity between all machines in the cluster

• Unique hostname, MAC address, and product_uuid for every node

• Certain ports are open on your machines (if your server is new, the required ports are already open)

Server Setup:

First two or more servers will be required where one will be master node (control plane) and the rest will be worker nodes. Shown here with Ubuntu 22.04 LTS. So you must have Ubuntu 22.04 LTS installed on your system.

• After creating three servers or nodes. Need to change or update the MAC address, product_uuid and hostname for every node including Master Node.

• Also, we need to check if the available port is free or open for the cluster

• Then permanently disable swap space on Master node. using this command:

    vi /ete/fstab
  

    #/swap.img      none    swap    sw      0       0
  

  After open the bash editor, then comment out or Add # before /swap.img

  Then forwarding IPv4 and letting iptables see bridged traffic:

    cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf
    overlay
    br_netfilter
    EOF
  
    sudo modprobe overlay
    sudo modprobe br_netfilter
  

  Then install some dependencies file for adding the repositories:

    apt-get update
    sudo apt-get install apt-transport-https ca-certificates curl gpg
  

  Install CRI-O on Server:

  Before installing CRI-O, we need to install some dependency packages:

•     curl -fsSL https://pkgs.k8s.io/addons:/cri-o:/prerelease:/main/deb/Release.key |
          gpg --dearmor -o /etc/apt/keyrings/cri-o-apt-keyring.gpg
  
      echo "deb [signed-by=/etc/apt/keyrings/cri-o-apt-keyring.gpg] https://pkgs.k8s.io/addons:/cri-o:/prerelease:/main/deb/ /" |
          tee /etc/apt/sources.list.d/cri-o.list
  

  Then update repository and install cri-o

•     apt-get update
      apt-get install socat
      apt-get install cri-o
  

  After installing cri-o, we need to start and enable crio.service

    systemctl enable crio.service
    systemctl start crio.service
    systemctl status crio.service
  

  Add the Kubernetes repository:

    curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.31/deb/Release.key |
        gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
  
    echo "deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.31/deb/ /" |
        tee /etc/apt/sources.list.d/kubernetes.list
  

  Installing process of Kubernetes:

  Now we have to install kubeadm, kubelet and kubectl, using below command:

    apt-get update
    sudo apt-get install kubelet kubeadm kubectl
    sudo apt-mark hold kubelet kubeadm kubectl
  

  Initialize Kubernetes Cluster:

  To initialize cluster, we have to run below command on master-node:

    kubeadm init
  

  Once the initialization is complete, some instructions will appear, which will help connect the worker nodes to the master node. This will contain a command to be run on the worker nodes.

  Create Cluster Join Token: (Control Plane)

    kubeadm token create --print-join-command
  

  You can generate a token by running this command. Through this token you can connect the worker nodes with the master node, if you go to those worker nodes and apply the token, then the worker node will be connected with the master node.

  Configuration of kubectl:

  Now set the kubeconfig on master-node, using below command:

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

  After the cluster set-up is completed, we have to set up the inter-cluster network system via CNI Plugin.

    kubectl apply -f https://reweave.azurewebsites.net/k8s/v1.31/net.yaml
  

  Verify the Cluster:

  Run the “kubectl get nodes” command on the master node to verify the cluster. You can see the status of the master and worker nodes.

  And this is how you can set up a Kubernetes Cluster.