📍 Introduction:

In the world of container orchestration, Kubernetes has emerged as the de facto standard. It provides a powerful platform for managing containerized applications, but setting up a Kubernetes cluster can be a daunting task. That's where Kubeadm comes to the rescue. In this guide, we'll walk you through the process of setting up a Kubernetes cluster using Kubeadm on Ubuntu.

🔍 Prerequisites ✅

Before we dive into the installation process, let's make sure we have everything we need:

• Ubuntu OS (Xenial or later): We'll use Ubuntu as our operating system.

• sudo privileges: You need administrative access to the servers.

• Internet access: To download necessary packages.

• t2.medium instance type or higher: This guide assumes you have access to suitable hardware.

• Both Master & Worker Node: For a fully functional cluster.

🔍 Installation Steps 🛠️

1. Update and Install Docker 🐳

   • Run the following commands on both the master and worker nodes to prepare them for Kubeadm:

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

     Kubernetes relies on Docker containers, so it's essential to have Docker installed and running on all nodes.

2. Add Kubernetes Repository and Install Kubeadm 📦

   • To add the Kubernetes repository and install Kubeadm, Kubectl, and Kubelet components, execute:

       curl -fsSL "https://packages.cloud.google.com/apt/doc/apt-key.gpg" | sudo gpg --dearmor -o /etc/apt/trusted.gpg.d/kubernetes-archive-keyring.gpg
       echo 'deb https://packages.cloud.google.com/apt kubernetes-xenial main' > /etc/apt/sources.list.d/kubernetes.list
     
       apt update -y
       apt install kubeadm=1.20.0-00 kubectl=1.20.0-00 kubelet=1.20.0-00 -y
     

3. Initialize the Kubernetes Master Node 🚀

   • Run this command to initialize the Kubernetes control plane on the master node:

       sudo su
       kubeadm init
     

4. Set Up Local Kubeconfig 📝

   • To interact with the Kubernetes cluster from your local machine, create the Kubeconfig file:

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

5. Apply Weave Network Plugin 🌐

   • Use this command to apply the Weave network plugin, which ensures pod-to-pod communication:

       kubectl apply -f https://github.com/weaveworks/weave/releases/download/v2.8.1/weave-daemonset-k8s.yaml
     

6. Generate Token for Worker Nodes 🤖

   • Generate a token for worker nodes to join the cluster:

       kubeadm token create --print-join-command
     

7. Expose Port 6443 for Worker Node Connectivity 🔗

   • Ensure that port 6443 is accessible from your worker nodes to the master node. This is essential for the worker nodes to communicate with the control plane.

🔍 Worker Node Setup 🏗️

1. Reset Kubeadm and Join Worker Node 🔄

   • On the worker node, execute the following commands:

       sudo su
       kubeadm reset pre-flight checks
     

     Then, paste the join command you obtained from the master node during token creation and append --v=5 for verbose output:

       kubeadm join <master-node-ip>:6443 --token <token> --discovery-token-ca-cert-hash <hash> --v=5
     

2. Verification ✔️

   • On the master node, run:

       kubectl get nodes
     

     This should display both the master and worker nodes as part of your Kubernetes cluster.

🔍 Optional Steps 🧐

• Labeling Nodes 🏷️: If you want to label your worker nodes for specific roles, you can use the following command:

    kubectl label node <node-name> node-role.kubernetes.io/worker=worker
  

• Testing a Demo Pod 🚀: To verify your cluster's functionality, you can deploy a demo pod:

    kubectl run nginx --image=nginx --port=80
    kubectl expose pod nginx --port=80 --type=NodePort
  

• Enable the port range 30000-32767 for the node-port on worker node

• Now, type the below command to know the node-port for the pod

kubectl get svc

• Node copy the public-ip of workernode: nodeport in the browser to get the nginx output

• 

  This will run a simple pod:

📍Conclusion:

Congratulations! You've successfully set up a Kubernetes cluster using Kubeadm on Ubuntu. This provides you with a powerful platform for deploying and managing containerized applications in a scalable and efficient manner. 🎉

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