Kubernetes Cluster Installation

This guide provides instructions for setting up a Kubernetes cluster on the following servers:

• Master Node: 10.254.59.161
• Worker Node 1: 10.254.59.162
• Worker Node 2: 10.254.59.163

Prerequisites

• All nodes should be CentOS-based.
• Ensure the nodes have internet access.
• Run the steps below on all nodes unless specified otherwise.

Step 1: Disable Swap and Set SELinux to Permissive

On all nodes, disable swap and set SELinux to permissive:

sudo swapoff -a
sudo setenforce 0
sudo sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

Step 2: Install Kubernetes and Docker

Add Kubernetes Repository On all nodes, add the Kubernetes repository:

cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://pkgs.k8s.io/core:/stable:/v1.30/rpm/
enabled=1
gpgcheck=1
gpgkey=https://pkgs.k8s.io/core:/stable:/v1.30/rpm/repodata/repomd.xml.key
exclude=kubelet kubeadm kubectl cri-tools kubernetes-cni
EOF

Install Kubernetes Components Install kubelet, kubeadm, and kubectl on all nodes:

sudo yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes

Install Docker

Install Docker on all nodes:

sudo yum install -y yum-utils
sudo dnf config-manager --add-repo=https://download.docker.com/linux/centos/docker-ce.repo
sudo dnf remove -y runc
sudo dnf install -y docker-ce --nobest

Start Docker

Enable and start Docker on all nodes:

sudo systemctl enable docker.service
sudo systemctl start docker.service

Configure Docker

On all nodes, create or modify the Docker daemon configuration file /etc/docker/daemon.json:

cat <<EOF | sudo tee /etc/docker/daemon.json
{
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "100m"
  },
  "storage-driver": "overlay2"
}
EOF

Restart Docker:

sudo systemctl restart docker

Configure Networking

Enable IP forwarding:

cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
net.ipv4.ip_forward = 1
EOF
sudo sysctl --system

Step 3: Set Hostnames and Update /etc/hosts

On each node, set the appropriate hostname and update /etc/hosts to map the IP addresses:

hostnamectl set-hostname <hostname>

Add the following entries to /etc/hosts on each node:

10.254.59.161 master
10.254.59.162 worker1
10.254.59.163 worker2

Step 4: Initialize Kubernetes on the Master Node

On the master node (10.254.59.161), pull the Kubernetes images:

sudo kubeadm config images pull

Initialize the cluster with the following command:

sudo kubeadm init --control-plane-endpoint=10.254.59.161 --pod-network-cidr=10.254.0.0/16

Configure kubectl on the Master Node

After the initialization, run the following commands to configure kubectl:

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 export the kubeconfig directly:

export KUBECONFIG=/etc/kubernetes/admin.conf

Step 5: Deploy a Pod Network

Deploy a pod network using a network plugin like Calico, Flannel, or others. For example, to use Calico, run:

kubectl apply -f https://docs.projectcalico.org/v3.25/manifests/calico.yaml

Refer to the Kubernetes add-ons documentation for other options.

Step 6: Join Worker Nodes to the Cluster

On each worker node (10.254.59.162 and 10.254.59.163), run the following command to join the cluster:

kubeadm join 10.254.59.161:6443 --token <token> \
    --discovery-token-ca-cert-hash sha256:<hash>

Replace and with the values provided during the master node initialization.

Step 7: Verify Cluster Status

On the master node, verify that all nodes have joined the cluster and are ready:

kubectl get nodes

You should see the master and worker nodes listed with the status Ready.

Conclusion

Congratulations! You have successfully set up a Kubernetes cluster with one master and two worker nodes. You can now deploy applications on your cluster.