Pre-installation Environment Setup for Kubernetes Cluster Deployment

Published: at 03:42 AM

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Introduction

Kubernetes is an open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications. It is widely used in the industry to manage containerized workloads and services. In this post, i will guide you through the pre-installation environment setup for Kubernetes cluster deployment. I will cover the installation of Docker, Kubectl, Kubeadm, Kubelet, and other necessary tools on Ubuntu 22.04 LTS.

Prerequisites

Before you begin, you should have the following prerequisites:

Step 1: Update the Package Repository And Disable Swap

First, you will need to update the package repository and disable the swap on your Ubuntu server. You can do this by running the following commands:

sudo apt update
sudo apt install -y curl \
  gnupg2 \
  software-properties-common \
  apt-transport-https \
  ca-certificates
sudo swapoff -a
sudo sed -i '/ swap / s/^\(.*\)$/#\1/g' /etc/fstab

Step 2: Setup Firewall Rules

Next, you will need to configure the firewall rules to allow the necessary ports for Kubernetes cluster.

For the Kubernetes control plane nodes, you will need to allow the following ports:

For the worker nodes, you will need to allow the following ports:

You can configure the firewall rules by running the following commands:

sudo ufw allow 6443/tcp
sudo ufw allow 2379:2380/tcp
sudo ufw allow 10250/tcp
sudo ufw allow 10259/tcp
sudo ufw allow 10257/tcp
sudo ufw allow 30000:32767/tcp
sudo ufw allow 10256/tcp
sudo ufw reload
sudo ufw enable

You can also disable the firewall if you are only using the Kubernetes cluster for testing purposes:

sudo ufw disable
systemctl disable --now ufw

Step 3: Load Necessary Kernel Modules

You will need to load the necessary kernel modules on your Ubuntu server. You can do this by running the following commands:

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

Step 4: Setup Iptables

You also need to configure the net bridge to allow the traffic to pass through the iptables rules. You can do this by running the following commands:

cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF
sudo sysctl --system

Step 5: Install Docker

Docker is a containerization platform that allows you to package, distribute, and run applications in containers. You can install Docker on your Ubuntu server by running the following commands:

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | \
  sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list
sudo apt update
sudo apt install -y containerd.io
sudo containerd config default | sudo tee /etc/containerd/config.toml
sudo sed -i 's/SystemdCgroup \= false/SystemdCgroup \= true/g' \
  /etc/containerd/config.toml
sudo systemctl restart containerd
sudo systemctl enable containerd

Step 6: Install Kubectl/Kubeadm/Kubelet

Kubectl is a command-line tool that allows you to run commands against Kubernetes clusters. Kubeadm is a tool that helps you bootstrap a Kubernetes cluster. Kubelet is an agent that runs on each node in the cluster and ensures that containers are running in a pod.

You can install Kubectl, Kubeadm, and Kubelet on your Ubuntu server by running the following commands:

curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.28/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:/v1.28/deb/ /" | \
  sudo tee /etc/apt/sources.list.d/kubernetes.list
sudo apt update
sudo apt install -y kubelet kubeadm kubectl
sudo apt-mark hold kubelet kubeadm kubectl

Step 7: Verify the Installation

You can verify the installation of Docker, Kubectl, Kubeadm, and Kubelet by running the following commands:

containerd -v
kubectl version --client
kubeadm version
kubelet --version

Conclusion

Accroding to the above steps, you have successfully set up the pre-installation environment for Kubernetes cluster deployment. If you want to make it automatic, you can use the following script to install all the necessary tools(run as root):

#!/bin/bash

echo "Installing Docker, Kubectl, Kubeadm, Kubelet, and other necessary tools on Ubuntu 22.04 LTS..."
echo "Updating the package repository..."
apt update
apt install -y curl gnupg2 software-properties-common apt-transport-https ca-certificates

echo "Disabling swap..."
swapoff -a
sed -i '/ swap / s/^\(.*\)$/#\1/g' /etc/fstab

echo "Setting up firewall rules..."
ufw allow 6443/tcp
ufw allow 2379:2380/tcp
ufw allow 10250/tcp
ufw allow 10259/tcp
ufw allow 10257/tcp
ufw allow 30000:32767/tcp
ufw allow 10256/tcp
ufw reload
ufw enable

echo "Loading necessary kernel modules..."
cat <<EOF | tee /etc/modules-load.d/k8s.conf
overlay
br_netfilter
EOF
modprobe overlay
modprobe br_netfilter

echo "Setting up iptables..."
cat <<EOF | tee /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF
sysctl --system

echo "Installing Docker..."
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | tee /etc/apt/sources.list.d/docker.list
apt update
apt install -y containerd.io
containerd config default | tee /etc/containerd/config.toml
sed -i 's/SystemdCgroup \= false/SystemdCgroup \= true/g' /etc/containerd/config.toml
systemctl restart containerd
systemctl enable containerd

echo "Installing Kubectl, Kubeadm, and Kubelet..."
curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.28/deb/Release.key | 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:/v1.28/deb/ /" | tee /etc/apt/sources.list.d/kubernetes.list
apt update
apt install -y kubelet kubeadm kubectl
apt-mark hold kubelet kubeadm kubectl

echo "Verifying the installation..."
containerd -v
kubectl version --client
kubeadm version
kubelet --version

References