kubeadm Cluster Setup: Step-by-Step Installation Guide

Setting up a Kubernetes cluster with kubeadm is a CKA exam requirement. This guide walks you through the complete process.

Prerequisites

System Requirements

• 2+ CPUs
• 2GB+ RAM
• Unique hostname, MAC, product_uuid
• Swap disabled
• Network connectivity

Prepare All Nodes

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

# Load kernel modules
cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf
overlay
br_netfilter
EOF

sudo modprobe overlay
sudo modprobe br_netfilter

# Networking settings
cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-iptables  = 1
net.bridge.bridge-nf-call-ip6tables = 1
net.ipv4.ip_forward                 = 1
EOF

sudo sysctl --system

Install Container Runtime (containerd)

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

# Configure containerd
sudo mkdir -p /etc/containerd
containerd config default | sudo tee /etc/containerd/config.toml
sudo sed -i 's/SystemdCgroup = false/SystemdCgroup = true/' /etc/containerd/config.toml
sudo systemctl restart containerd

Install kubeadm, kubelet, kubectl

# Add Kubernetes repo
sudo apt-get update
sudo apt-get install -y apt-transport-https ca-certificates curl

curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.29/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:/v1.29/deb/ /' | sudo tee /etc/apt/sources.list.d/kubernetes.list

# Install packages
sudo apt-get update
sudo apt-get install -y kubelet kubeadm kubectl
sudo apt-mark hold kubelet kubeadm kubectl

Initialize Control Plane

# On control plane node
sudo kubeadm init --pod-network-cidr=10.244.0.0/16

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

Install CNI (Calico)

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

Join Worker Nodes

# On worker nodes (use token from kubeadm init output)
sudo kubeadm join <control-plane-ip>:6443 --token <token> \
  --discovery-token-ca-cert-hash sha256:<hash>

Verify Cluster

kubectl get nodes
kubectl get pods -n kube-system

Common Issues

Practice Cluster Setup

Cluster installation is tested in CKA exams. Practice at Sailor.sh.

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