k8s_setup.sh

k8s_setup.sh

#!/bin/bash
################################################################################
# Kubernetes v1.33 & Cilium Installer for Debian
#
# This script installs Kubernetes version v1.33 on a plain-vanilla Debian system
# using kubeadm, kubelet, and kubectl via the new package repository hosted at
# pkgs.k8s.io. It also installs containerd (configured with the systemd cgroup
# driver) as the container runtime, disables swap, and deploys Cilium as the CNI.
#
# Prerequisites:
#   - Compatible Linux host with at least 2GB RAM and 2 CPUs.
#   - Unique hostname, MAC address, and product_uuid on every node.
#   - Required ports (e.g., 6443 for API server) open.
#
# Usage: Run this script as root:
#   sudo ./k8s_install.sh
################################################################################

# Exit immediately on error, treat unset variables as errors, and propagate pipeline errors.
set -euo pipefail
IFS=$'\n\t'

# Log file location
LOG_FILE="/var/log/k8s_install.log"
: > "$LOG_FILE"
chmod 644 "$LOG_FILE"

# Logging functions
log_info() {
    echo "$(date +'%Y-%m-%d %H:%M:%S') [INFO] $*" | tee -a "$LOG_FILE"
}
log_warn() {
    echo "$(date +'%Y-%m-%d %H:%M:%S') [WARN] $*" | tee -a "$LOG_FILE"
}
log_error() {
    echo "$(date +'%Y-%m-%d %H:%M:%S') [ERROR] $*" | tee -a "$LOG_FILE" >&2
}

# Ensure the script is run as root
if [ "$EUID" -ne 0 ]; then
    log_error "This script must be run as root. Exiting."
    exit 1
fi

log_info "Starting Kubernetes v1.33 installation on Debian..."

###############################################################################
# Pre-Installation: Update apt and install prerequisites
###############################################################################
log_info "Updating apt repositories..."
apt-get update -y >> "$LOG_FILE" 2>&1

log_info "Installing prerequisites: apt-transport-https, ca-certificates, curl, gpg..."
apt-get install -y apt-transport-https ca-certificates curl gpg >> "$LOG_FILE" 2>&1

###############################################################################
# Install and Configure containerd as the Container Runtime
###############################################################################
log_info "Installing containerd..."
apt-get install -y containerd >> "$LOG_FILE" 2>&1

log_info "Generating default containerd configuration..."
# Generate a default configuration file for containerd
containerd config default > /etc/containerd/config.toml

log_info "Configuring containerd to use the systemd cgroup driver..."
# Ensure that containerd uses systemd as the cgroup driver for compatibility with kubelet.
if ! grep -q "SystemdCgroup = true" /etc/containerd/config.toml; then
    # Append the setting under the correct section
    sed -i '/\[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc.options\]/a \ \ \ \ SystemdCgroup = true' /etc/containerd/config.toml
fi
systemctl restart containerd
log_info "containerd installation and configuration completed."

###############################################################################
# Set Up the Kubernetes v1.33 Package Repository (pkgs.k8s.io)
###############################################################################
log_info "Setting up the Kubernetes v1.33 apt repository..."

# Create the keyrings directory if it does not exist (required on older Debian/Ubuntu)
mkdir -p /etc/apt/keyrings

# Download the public signing key and save it in the keyrings directory
curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.33/deb/Release.key | gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg

# Overwrite any existing configuration in the Kubernetes sources list
echo 'deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.33/deb/ /' | tee /etc/apt/sources.list.d/kubernetes.list

log_info "Updating apt repositories after adding Kubernetes repo..."
apt-get update -y >> "$LOG_FILE" 2>&1

###############################################################################
# Install kubeadm, kubelet, and kubectl (Kubernetes v1.33)
###############################################################################
if ! command -v kubeadm &> /dev/null; then
    log_info "Installing kubeadm, kubelet, and kubectl (Kubernetes v1.33)..."
    apt-get install -y kubelet kubeadm kubectl >> "$LOG_FILE" 2>&1
    log_info "Pinning Kubernetes packages to prevent unintended upgrades..."
    apt-mark hold kubelet kubeadm kubectl
else
    log_info "Kubernetes components are already installed. Skipping installation."
fi

# Enable the kubelet service
log_info "Enabling and starting kubelet service..."
systemctl enable --now kubelet >> "$LOG_FILE" 2>&1

###############################################################################
# Swap Configuration (Disable Swap)
###############################################################################
log_info "Disabling swap (Kubelet requires swap to be off)..."
swapoff -a >> "$LOG_FILE" 2>&1
# Comment out swap entries in /etc/fstab to disable swap on reboot
sed -i '/ swap / s/^/#/' /etc/fstab
log_info "Swap disabled."

###############################################################################
# Pre-Flight Checks Reminder
###############################################################################
log_info "IMPORTANT: Ensure that your node has a unique hostname, MAC address, and product_uuid."
log_info "You can verify these using 'hostname', 'ip link' and 'cat /sys/class/dmi/id/product_uuid'."
# (For multi-node clusters, verify that these values are unique to each node.)

###############################################################################
# Initialize the Kubernetes Cluster with kubeadm
###############################################################################
if [ ! -f /etc/kubernetes/admin.conf ]; then
    log_info "Initializing Kubernetes cluster with kubeadm..."
    # --pod-network-cidr is set to 10.244.0.0/16 (adjust if using a different CNI)
    kubeadm init --pod-network-cidr=10.244.0.0/16 >> "$LOG_FILE" 2>&1
    if [ $? -eq 0 ]; then
        log_info "Kubernetes cluster initialized successfully."
    else
        log_error "Kubernetes initialization failed. Check the log for details."
        exit 1
    fi

    # Set up kubeconfig for root (adjust if using non-root users)
    export KUBECONFIG=/etc/kubernetes/admin.conf
else
    log_info "Kubernetes cluster already initialized. Skipping kubeadm init."
    export KUBECONFIG=/etc/kubernetes/admin.conf
fi

# Allow control plane components to stabilize
log_info "Waiting for the Kubernetes control plane to stabilize..."
sleep 15