Step-by-Step Guide: Setting up a Kubernetes Cluster with Kubeadm

First Install and start Docker on the master and worker nodes.

1. 1. First, update the server by running the following command:

        sudo apt-get update
      

      1. Install Docker by running the following command:

         sudo apt-get install docker.io
         

      2. Add the current user to the Docker group, so you can use Docker without sudo:

         sudo usermod -a -G docker $USER
         

      3. Reboot the system for the changes to take effect:

         sudo reboot
         

Congratulations, Docker is now installed on your Ubuntu system!

1. Install the library for Kubeadm:

   sudo curl -fsSLo /usr/share/keyrings/kubernetes-archive-keyring.gpg https://packages.cloud.google.com/apt/doc/apt-key.gpg

   echo "deb [signed-by=/usr/share/keyrings/kubernetes-archive-keyring.gpg] https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list

2. Install Kubeadm and other necessary tools:

   sudo apt-get install -y kubelet=1.20.0-00 kubectl=1.20.0-00 kubeadm=1.20.0-00

3. Become root user using sudo su and initialize Kubeadm by running the following command on the master node:

   kubeadm init

   You will see a message indicating that your Kubernetes control-plane has initialized successfully. To start using your cluster, you need to run the following as a regular user:

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

   Alternatively, if you are the root user, you can run:

   export KUBECONFIG=/etc/kubernetes/admin.conf

   This will set the KUBECONFIG environment variable to the location of the Kubernetes configuration file.

4. To verify that your cluster is up and running, run the following command:

   kubectl get nodes

   You should see an output listing the nodes in your cluster.

5. Create a network for your Kubernetes cluster by deploying the Weave Net CNI plugin. Run the following command:

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

   This command will deploy the Weave Net daemonset, which ensures that a copy of a pod runs on every node in the cluster. The Weave Net CNI plugin provides network connectivity between pods and services within a Kubernetes cluster.

6. Generate a token that worker nodes can use to connect to the master. Run the following command:

   kubeadm token create --print-join-command

   This will output a command that you can use to join worker nodes to the cluster. Make note of the command, as you will need it when joining worker nodes.

7. On each worker node, become root using sudo su and reset Kubeadm pre-flight checks:

   kubeadm reset

8. Join the worker nodes to the cluster by running the join command that was generated in step 6. Run the following command on each worker node:

    kubeadm join 172.31.20.154:6443 --token 0ehf8k.mkq70s47jh5er3tu --discovery-token-ca-cert-hash sha256:5c6d671834c7d4f36c1f1a57b1c89e90d2a9e4efe1034c632d3575dd6ec41abe --v=5
   

   Replace the IP address with the IP address of your master node. This command will join the worker node to the cluster.

9. Verify that the worker nodes have joined the cluster by running the following command on the master node:

   kubectl get nodes

   You should see all the worker nodes listed as part of your cluster.

   Congratulations! You have successfully set up a Kubernetes cluster with one master node and multiple worker nodes. Now, you can start deploying and managing containerized applications using Kubernetes.

   However, keep in mind that this is just a basic setup guide, and there are many other aspects of Kubernetes that you may want to explore, such as:

   • Creating and managing deployments

   • Configuring services and load balancing

   • Scaling and autoscaling your applications

   • Configuring storage and volumes

   • Implementing security measures

   • Monitoring and logging your cluster

To learn more about these topics and more, check out the Kubernetes documentation and community resources. Happy Kubernetizing!