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Setup K8S control-plane (master) and worker nodes

Setting up a Kubernetes (K8S) cluster involves configuring control-plane (master) and worker nodes. Below is a step-by-step guide to set up a basic Kubernetes cluster using kubeadm.

Prepare All Nodes (Master & Worker Nodes)

Perform these steps on all nodes (control-plane and workers).

Prerequisites

  • Update System and Install Dependencies

    Update the system and install required tools
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    sudo apt-get update
sudo apt-get install -y apt-transport-https ca-certificates curl gpg

  • Disable Swap (Required)

    Kubernetes requires swap to be disabled
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    # Backup the fstab file
sudo cp /etc/fstab /etc/fstab.bak

# Comment out the swap line
sudo sed -i '/swap/s/^/#/' /etc/fstab  # Permanent disable

# Disable all swap spaces
sudo swapoff -a

# View swap space status
sudo swapon --show

  • Enable IPv4 forward

    Enable IPv4 forward
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    sudo sed -i 's/^#*net.ipv4.ip_forward=1/net.ipv4.ip_forward = 1/' /etc/sysctl.conf

sudo sysctl -p

Install Container Runtime (containerd)

  • Install containerd

    Install containerd
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    # Install containerd
sudo apt update
sudo apt install -y containerd

  • Configure containerd

    Configure containerd
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    sudo mkdir -p /etc/containerd

containerd config default | sudo tee /etc/containerd/config.toml

  • Enable systemd cgroup driver

    Enable systemd cgroup driver
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    sudo sed -i 's/SystemdCgroup\s*=\s*false/SystemdCgroup = true/i' /etc/containerd/config.toml

  • Restart containerd

    Restart containerd
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    sudo systemctl restart containerd
sudo systemctl enable containerd

Install Kubernetes Components

  • Add Kubernetes APT repository

    Add Kubernetes APT repository
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    curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.32/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg

echo 'deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.32/deb/ /' | sudo tee /etc/apt/sources.list.d/kubernetes.list

  • Install Kubernetes tools

    Install Kubernetes tools
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    sudo apt update
sudo apt install -y kubelet kubeadm kubectl
sudo apt-mark hold kubelet kubeadm kubectl  # Prevent auto-upgrades

Initialize Cluster (Master Node)

Perform these steps only on the control-plane node.

Set Hostname

Set unique hostnames (e.g., k8s-control-plane)

Set Hostname
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# Set a unique hostname
sudo hostnamectl set-hostname k8s-control-plane

# View hostname information
hostnamectl status

# Clear the hostname, the system will use the default value
hostnamectl set-hostname ""

Initialize Cluster

  • Initialize the control-plane with kubeadm

    Initialize the control-plane with kubeadm
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    # sudo kubeadm init --pod-network-cidr=<cidr> --control-plane-endpoint=<control-plane-ip>
sudo kubeadm init --pod-network-cidr=10.227.0.0/16 --control-plane-endpoint=10.227.xxx.xxx

# Clean up the current cluster configuration on all control plane and worker nodes
# sudo kubeadm reset -f

  • /etc/kubernetes/ directory structure

    /etc/kubernetes/ Directory Structure
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    /etc/kubernetes/
├── admin.conf               # Cluster configuration file with admin privileges
├── controller-manager.conf  # Configuration file for the controller manager
├── kubelet.conf             # Configuration file for the kubelet component
├── scheduler.conf           # Configuration file for the scheduler
├── manifests/               # Directory for static Pod manifests
└── pki/                     # Directory for certificates and keys

Configure kubectl

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

export KUBECONFIG=/etc/kubernetes/admin.conf

Install CNI Plugin (Calico)

  • Apply CNI network

    Apply CNI network
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    # Option#1: Apply Calico network
# Apply Calico CNI network plugin configuration to the Kubernetes cluster
kubectl apply -f https://docs.projectcalico.org/manifests/calico.yaml

# Delete the Calico network plugin resources from the cluster
# kubectl delete -f https://docs.projectcalico.org/manifests/calico.yaml
# ######################################################################
# Option#2: Apply Flannel network
# Apply Flannel CNI network plugin configuration to the Kubernetes cluster
curl https://raw.githubusercontent.com/flannel-io/flannel/master/Documentation/kube-flannel.yml -o kube-flannel.yml
sed -i 's/\("Network":\s*"\).*\(\/[0-9]*\)"/\110.227.0.0\2"/' kube-flannel.yml
kubectl apply -f kube-flannel.yml

# Apply Flannel CNI network plugin configuration to the Kubernetes cluster
# kubectl apply -f https://raw.githubusercontent.com/flannel-io/flannel/master/Documentation/kube-flannel.yml
# Delete the Flannel network plugin resources from the cluster
# kubectl delete -f https://raw.githubusercontent.com/flannel-io/flannel/master/Documentation/kube-flannel.yml

  • Wait for pods to be ready

    Wait for pods to be ready
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    kubectl get pods -n kube-system --watch

Join Cluster (Worker Nodes)

Perform these steps on each worker node.

Set Hostname

Set unique hostnames (e.g., k8s-worker1, k8s-worker2)

Set unique hostname
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sudo hostnamectl set-hostname k8s-worker1

Join Cluster

Run the kubeadm join command from the control-plane node’s kubeadm init output.

Join cluster
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# sudo kubeadm join <control-plane-ip>:6443 --token <token> --discovery-token-ca-cert-hash sha256:<hash>
sudo kubeadm join 10.227.xxx.xxx:6443 --token 2ln8mt.1d91gun25pjdjvz8 --discovery-token-ca-cert-hash sha256:bb1de2c2e112b97d52870e4573bdc8d5caa75a4310f0e10697ddd5bf0827a928

# This kubeadm reset command undoess the effects of 'kubeadm init' or 'kubeadm join'
# a. Removes Kubernetes-managed containers (pods, deployments, etc.)
# b. Cleans up iptables rules and IPVS configurations set by Kubernetes
# c. Deletes the kubelet configuration (/var/lib/kubelet/)
# d. Removes certificates and keys generated by kubeadm init or kubeadm join
# e. Erases cluster-related data (etcd, if running locally)
# sudo kubeadm reset

Verify Cluster (Master Node)

Perform these steps only on the control-plane node.

Verify Cluster

On the control-plane node, check node status.

Verify cluster
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kubectl get nodes
All nodes should appear in the Ready state.

Test Cluster

  • Deploy nginx application

    Deploy nginx application
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    kubectl create deployment nginx --image=nginx --replicas=2

  • Expose nginx service

    Expose nginx service
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    kubectl expose deployment nginx --port=80 --type=NodePort

  • Test nginx deployment service

    Test nginx service
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    # Get NodePort (30000-32767)
NODE_PORT=$(kubectl get service nginx -o jsonpath='{.spec.ports[0].nodePort}')

# Get any NodeIP
NODE_IP=$(kubectl get nodes -o jsonpath='{.items[0].status.addresses[0].address}')

# Accessing using curl
curl http://$NODE_IP:$NODE_PORT
    Access Nginx using any NodeIP and the assigned NodePort.