☑️Day 32: Creating Multi Node Cluster in Kubernetes🚀

Kubernetes multi-node clusters are essential for deploying scalable applications across multiple machines. In this newsletter, I’ll guide you step-by-step through the process of setting up a multi-node Kubernetes cluster on CentOS using VMware.

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✅What is a Multi-Node Kubernetes Cluster?

• A multi-node cluster consists of one master node (control plane) and multiple worker nodes.

• Master node handles the management of the cluster, while worker nodes handle the actual running of your applications.

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✅Steps for Setting Up a Multi-Node Kubernetes Cluster

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Step 1: Set Up Virtual Machines (VMs) on VMware

1. Create VMs:

   • VM1: Master node (control plane)

   • VM2 & VM3: Worker nodes

   • Allocate at least 2 GB RAM and 2 vCPUs to each node.

   • Install CentOS on all nodes.

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Step 2: Prepare Nodes

1. Update all systems: On each node, run:

    bashCopy codeyum update -y
   

2. Disable Swap (Kubernetes does not support swap):

    bashCopy codeswapoff -a
    sed -i '/swap/d' /etc/fstab
   

3. Disable Firewall:

    bashCopy codesystemctl stop firewalld
    systemctl disable firewalld
   

4. Ensure that the IP forwarding is enabled:

    bashCopy codeecho 1 > /proc/sys/net/ipv4/ip_forward
   

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Step 3: Install Docker

1. Install Docker on all nodes:

    bashCopy codeyum install docker -y
    systemctl start docker
    systemctl enable docker
   

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Step 4: Install Kubernetes

1. Install kubeadm, kubelet, and kubectl on all nodes:

    bashCopy codecat <<EOF > /etc/yum.repos.d/kubernetes.repo
    [kubernetes]
    name=Kubernetes
    baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64
    enabled=1
    gpgcheck=1
    repo_gpgcheck=1
    gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
    EOF
   
    yum install -y kubelet kubeadm kubectl
    systemctl enable kubelet
    systemctl start kubelet
   

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Step 5: Initialize Kubernetes Master Node

1. On the master node (VM1), initialize Kubernetes:

    bashCopy codekubeadm init --pod-network-cidr=192.168.0.0/16
   

2. Configure kubectl for master node:

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

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Step 6: Set Up a Pod Network

1. Install Calico as the pod network (on the master node):

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

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Step 7: Join Worker Nodes to the Cluster

1. On the master node, after the init process, you’ll get a join token. It looks like this:

    bashCopy codekubeadm join <master-ip>:6443 --token <token> --discovery-token-ca-cert-hash sha256:<hash>
   

2. Run this command on both worker nodes (VM2 & VM3) to join them to the master node:

    bashCopy codekubeadm join <master-ip>:6443 --token <token> --discovery-token-ca-cert-hash sha256:<hash>
   

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Step 8: Verify the Cluster

1. On the master node, check if all nodes have joined successfully:

    bashCopy codekubectl get nodes
   

   You should see the master and worker nodes listed.

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✅Important Commands Recap

• Install Kubernetes components on each node:

    bashCopy codeyum install -y kubelet kubeadm kubectl
  

• Disable swap on all nodes:

    bashCopy codeswapoff -a
  

• Initialize the master node:

    bashCopy codekubeadm init --pod-network-cidr=192.168.0.0/16
  

• Join worker nodes to the cluster:

    bashCopy codekubeadm join <master-ip>:6443 --token <token> --discovery-token-ca-cert-hash sha256:<hash>
  

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✅Key Concepts to Remember:

• Master Node: Controls the Kubernetes cluster.

• Worker Nodes: Run the application containers.

• Pod Network: Allows communication between Kubernetes pods across nodes.

• Calico: A popular networking option for Kubernetes clusters.

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✅Real-Time Use Case:

A multi-node Kubernetes cluster can be used for high-availability applications. For example, in a production environment, a web application can be deployed across multiple worker nodes. If one node fails, Kubernetes ensures the application stays up by distributing the load across the remaining nodes.

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🚀Thanks for joining me on Day 32! Let’s keep learning and growing together!

Happy Learning! 😊

#90DaysOfDevOps