Kubernetes Cluster Setup

Kubernetes Cluster Setup

Bootstrap a Kubernetes cluster using kubeadm.

Prerequisites

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

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

sudo modprobe overlay
sudo modprobe br_netfilter

# Sysctl params
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

Step 1: Install Container Runtime

# Install containerd (all nodes)
sudo apt update
sudo apt install containerd -y

# Configure containerd
sudo mkdir -p /etc/containerd
containerd config default | sudo tee /etc/containerd/config.toml

# Enable SystemdCgroup
sudo sed -i 's/SystemdCgroup = false/SystemdCgroup = true/' /etc/containerd/config.toml

sudo systemctl restart containerd
sudo systemctl enable containerd

Step 2: Install kubeadm, kubelet, kubectl

# All nodes
sudo apt update
sudo apt install -y apt-transport-https ca-certificates curl

# Add Kubernetes repo
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
sudo apt update
sudo apt install -y kubelet kubeadm kubectl
sudo apt-mark hold kubelet kubeadm kubectl

Step 3: Initialize Control Plane

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

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

# Save the join command!
# kubeadm join <ip>:6443 --token <token> --discovery-token-ca-cert-hash sha256:<hash>

Step 4: Install CNI (Flannel)

# On control plane
kubectl apply -f https://github.com/flannel-io/flannel/releases/latest/download/kube-flannel.yml

# Verify
kubectl get pods -n kube-flannel

Step 5: Join Worker Nodes

# On each worker node
sudo kubeadm join <control-plane-ip>:6443 \
  --token <token> \
  --discovery-token-ca-cert-hash sha256:<hash>

# If token expired, create new one on control plane:
kubeadm token create --print-join-command

Step 6: Verify Cluster

# Check nodes
kubectl get nodes

# Check system pods
kubectl get pods -n kube-system

# Cluster info
kubectl cluster-info

Step 7: Install Metrics Server

kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml

# For local clusters, add to deployment:
# args: --kubelet-insecure-tls

# Verify
kubectl top nodes
kubectl top pods -A

Deploy Test Application

# Create deployment
kubectl create deployment nginx --image=nginx

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

# Get NodePort
kubectl get svc nginx

# Test
curl http://<node-ip>:<nodeport>

Essential Commands