Kubernetes - script for setting up master and worker

 

We’ll create two scripts:

1. k8s-node-setup.sh → run on all nodes (control-plane + workers)

2. k8s-master-init.sh → run only on the control-plane to initialize the cluster

1. k8s-node-setup.sh (all nodes)

This script prepares Ubuntu for Kubernetes, installs containerd, kubeadm, kubelet, kubectl.

#!/bin/bash

set -e

echo "[Step 0] Updating system..."

sudo apt-get update -y

echo "[Step 1] Disabling swap..."

sudo swapoff -a

sudo sed -ri '/\sswap\s/s/^/#/' /etc/fstab

echo "[Step 2] Loading kernel modules..."

cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf

overlay

br_netfilter

EOF

sudo modprobe overlay

sudo modprobe br_netfilter

echo "[Step 3] Setting sysctl params..."

cat <<EOF | sudo tee /etc/sysctl.d/kubernetes.conf

net.bridge.bridge-nf-call-iptables  = 1

net.bridge.bridge-nf-call-ip6tables = 1

net.ipv4.ip_forward                 = 1

EOF

sudo sysctl --system

echo "[Step 4] Installing containerd..."

sudo apt-get install -y containerd

sudo mkdir -p /etc/containerd

containerd config default | sudo tee /etc/containerd/config.toml >/dev/null

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

sudo systemctl enable --now containerd

sudo systemctl restart containerd

echo "[Step 5] Installing kubeadm, kubelet, kubectl..."

sudo apt-get install -y apt-transport-https ca-certificates curl gpg

sudo mkdir -p /etc/apt/keyrings

curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.33/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:/v1.33/deb/ /" \

| sudo tee /etc/apt/sources.list.d/kubernetes.list

sudo apt-get update

sudo apt-get install -y kubelet kubeadm kubectl

sudo apt-mark hold kubelet kubeadm kubectl

echo "✅ Node prep complete. Ready for kubeadm init (control-plane) or join (workers)."

2. k8s-master-init.sh (control-plane only)

This initializes the control-plane with Calico networking.

#!/bin/bash

set -e

POD_CIDR="192.168.0.0/16"

API_ADVERTISE_IP=$(hostname -I | awk '{print $1}')

echo "[Step 1] Initializing Kubernetes control-plane..."

sudo kubeadm init \

  --pod-network-cidr=${POD_CIDR} \

  --apiserver-advertise-address=${API_ADVERTISE_IP}

echo "[Step 2] Setting up kubeconfig for current user..."

mkdir -p $HOME/.kube

sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config

sudo chown $(id -u):$(id -g) $HOME/.kube/config

echo "[Step 3] Installing Calico CNI..."

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

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

echo "✅ Control-plane initialized. Workers can now join using the kubeadm join command printed above."

3. Worker join command

After running the master init script, copy the kubeadm join ... line that is printed and run it on each worker node.

If you need a new token later:

sudo kubeadm token create --print-join-command