Deploying a Multi-Node Kubernetes Cluster with Kubeadm

Infrastructure Requirements

Before initiating the deployment, ensure your environment meets the following specifications:

Operating System: CentOS 7.x (64-bit).
Hardware: Minimum 2 CPUs, 2GB RAM, and 30GB disk space.
Connectivity: Full network interoperability between all nodes and internet access for image retrieval.
System State: Swap must be permanently disabled.

Node Configuration

This setup utilizes three virtual instances:

Control Plane (Master): 192.168.31.61 (hostname: k8s-master)
Worker Node 01: 192.168.31.62 (hostname: k8s-node1)
Worker Node 02: 192.168.31.63 (hostnmae: k8s-node2)

OS Initialization

Execute these configuration steps on all nodes to prepare the environment.

Security and Swap Management

Disable the firewall and SELinux to prevent interference with inter-node communication:

systemctl stop firewalld && systemctl disable firewalld
setenforce 0
sed -i 's/^SELINUX=enforcing$/SELINUX=disabled/' /etc/selinux/config

Turn off swap space to ensure the Kubelet functions correctly:

swapoff -a
sed -i '/swap/s/^/#/' /etc/fstab

Networking and Host Resolution

Map the hostnames in /etc/hosts for consistent resolution:

cat <<EOF >> /etc/hosts
192.168.31.61 k8s-master
192.168.31.62 k8s-node1
192.168.31.63 k8s-node2
EOF

Configure the kernel to allow bridged IPv4 traffic to reach iptables chains:

cat <<EOF > /etc/sysctl.d/kubernetes.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF
sysctl --system

Sync the system clock:

yum install ntpdate -y
ntpdate time.windows.com

Installing Container Runtime and Kubernetes Toooling

Kubernetes requires a Container Runtime Interface (CRI). Here, we install Docker CE and the Kubernetes binaries (kubeadm, kubectl, kubelet).

Docker Setup

wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo
yum -y install docker-ce-18.06.1.ce-3.el7
systemctl enable docker && systemctl start docker

Kubernetes Repositories and Packages

Configure the package manager to use the Kubernetes mirror and install the toolset:

cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
EOF

yum install -y kubelet kubeadm kubectl
systemctl enable kubelet

Initializing the Control Plane

On the Master node (192.168.31.61), initialize the cluster. We specify a mirror repository to avoid connection issues with the default Google registry.

kubeadm init \
  --apiserver-advertise-address=192.168.31.61 \
  --image-repository registry.aliyuncs.com/google_containers \
  --kubernetes-version v1.17.0 \
  --service-cidr=10.96.0.0/12 \
  --pod-network-cidr=10.244.0.0/16

After the processs completes, configure kubectl for the local user:

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

Deploying the Pod Network

Apply the Flannel CNI plugin to enable networking between Pods:

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

Integrating Worker Nodes

On each worker node, use the join command generated during the kubeadm init phase. It will look similar to this:

kubeadm join 192.168.31.61:6443 --token <token> --discovery-token-ca-cert-hash sha256:<hash>

Verify that all nodes have successfully joined the cluster by running kubectl get nodes on the Master.

Verifying the Cluster

Deploy a sample Nginx workload to confirm the cluster is operational:

kubectl create deployment web-server --image=nginx
kubectl expose deployment web-server --port=80 --type=NodePort
kubectl get pods,svc

You can access the Nginx service via the assigned NodePort on any cluster node's IP address.

Tags: kubernetes kubeadm Cluster Deployment Linux Administration docker

Posted on Sun, 23 Aug 2026 16:25:06 +0000 by fatepower

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