K8S Installation Script

#!/bin/bash

set -euo pipefail

# Define network and host details

NIC="ens160"

IP="192.168.1.24/24"

GW="192.168.1.1"

DNS="192.168.1.1"

# Configure static IP

nmcli connection modify $NIC ipv4.addresses "$IP"

nmcli connection modify $NIC ipv4.gateway "$GW"

nmcli connection modify $NIC ipv4.dns "$DNS"

nmcli connection modify $NIC ipv4.method manual

nmcli connection down $NIC || true

nmcli connection up $NIC

# Verify

nmcli device show $NIC

# Update /etc/hosts safely

declare -A HOST_ENTRIES=(

["192.168.1.18"]="k8s-master"

["192.168.1.15"]="k8s-node1"

["192.168.1.19"]="k8s-node2"

["192.168.1.24"]="mini"

)

for ip in "${!HOST_ENTRIES[@]}"; do

host="${HOST_ENTRIES[$ip]}"

grep -q "$ip" /etc/hosts || echo "$ip $host" | sudo tee -a /etc/hosts

done

# System update

dnf -y update

# Disable firewall and swap

systemctl disable --now firewalld

swapoff -a

sed -i '/swap/d' /etc/fstab

# Disable SELinux

setenforce 0 || true

sed -i 's/^SELINUX=enforcing/SELINUX=disabled/' /etc/selinux/config

# Enable kernel modules

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

overlay

br_netfilter

EOF

modprobe overlay

modprobe br_netfilter

# Set sysctl params

cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf

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

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

net.ipv4.ip_forward = 1

EOF

sysctl --system

# Verify modules

lsmod | grep overlay || echo "overlay not loaded"

lsmod | grep br_netfilter || echo "br_netfilter not loaded"

# Install containerd dependencies

dnf install -y yum-utils device-mapper-persistent-data lvm2

# Add Docker repo for containerd

yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo

# Install containerd

dnf install -y containerd.io

# Configure containerd

mkdir -p /etc/containerd

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

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

# Enable containerd

systemctl daemon-reexec

systemctl enable --now containerd

containerd --version

systemctl status containerd --no-pager

# Add Kubernetes YUM repo

cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo

[kubernetes]

name=Kubernetes

baseurl=https://pkgs.k8s.io/core:/stable:/v1.31/rpm/

enabled=1

gpgcheck=1

gpgkey=https://pkgs.k8s.io/core:/stable:/v1.31/rpm/repodata/repomd.xml.key

exclude=kubelet kubeadm kubectl

EOF

# Update and install Kubernetes tools

dnf update -y

dnf install -y kubelet kubeadm kubectl --disableexcludes=kubernetes

# Enable kubelet

systemctl enable --now kubelet

systemctl status kubelet --no-pager

k8s installation script.txt

Displaying k8s installation script.txt.