Setting Up a Kubernetes Cluster on Ubuntu 20.04

Hey guys! So, you’re looking to dive into the world of Kubernetes, huh? Awesome! Kubernetes, often shortened to K8s, is like the brain of your containerized applications. It’s the go-to platform for automating deployment, scaling, and managing these apps. And what’s even better is that setting up a Kubernetes cluster on Ubuntu 20.04 is totally doable, even if you’re just starting out. In this guide, we’ll walk you through every step, from prepping your Ubuntu machines to deploying your first app. We’ll be using kubeadm for our setup, which is the official tool from Kubernetes itself, making the whole process smooth and straightforward. Get ready to spin up your own cluster and start orchestrating your applications like a pro! This tutorial is designed to be beginner-friendly, so don’t worry if you’re new to Kubernetes. We’ll break down everything into easy-to-follow steps.

Before we jump in, let’s talk about why you’d want to use Kubernetes. Imagine you have a bunch of applications running in containers. Managing these containers manually can quickly become a headache, especially as your application grows. Kubernetes solves this by providing a platform to automate all sorts of tasks: deployment, scaling, and the management of containerized applications. It ensures your applications are always up and running, and it takes care of things like load balancing and self-healing. So, if you’re looking to modernize your application deployment, increase efficiency, and have more control over your infrastructure, Kubernetes is the way to go. And Ubuntu 20.04 is an excellent platform for this, offering a stable and reliable environment to run your cluster.

Prerequisites

Before getting started, make sure you have a few things in place. First, you’ll need at least two Ubuntu 20.04 servers (or virtual machines). One will act as the master node , which controls the cluster, and the other(s) will be worker nodes, where your applications will run. For this tutorial, we will set up one master node and one worker node. Ensure that you have a user with sudo privileges on each server. Also, make sure that you can SSH into each server. It’s also a good idea to update all the packages on your servers before you begin. You can do this by running sudo apt update && sudo apt upgrade -y . Now is also a great time to ensure that your machines have a static IP address. While DHCP can work, it can make it harder to manage the cluster. And last but not least, make sure your firewalls are set up correctly. By default, Ubuntu has the ufw firewall enabled. You’ll need to allow traffic on specific ports for the Kubernetes components to communicate.

Step 1: Preparing Your Ubuntu Machines

Okay, before we get into the nitty-gritty of Kubernetes installation , we need to prep our Ubuntu machines. This step is crucial because it ensures that our systems are ready for the installation. We’re talking about disabling swap, configuring the networking, and making sure that all the necessary packages are installed. Think of it as laying the foundation for a strong and stable cluster. First, let’s disable swap. Kubernetes doesn’t play well with swap, so it’s essential to turn it off on all of your nodes. You can do this by running sudo swapoff -a to immediately disable swap and then sudo nano /etc/fstab to comment out any swap entries to prevent them from coming back on reboot. Simply add a # at the beginning of the line that starts with swap . Then save and close the file. Next, we need to ensure that iptables uses the br_netfilter module. Kubernetes uses iptables for networking, and the br_netfilter module is necessary for proper communication between the containers. You can enable it by running sudo modprobe br_netfilter . Also, we need to configure the networking to allow traffic to the containers. Apply the following configurations by running the following commands. sudo sysctl -w net.ipv4.ip_forward=1 and sudo sysctl -w net.bridge.bridge-nf-call-iptables=1 . To make these changes permanent, add these lines to /etc/sysctl.conf : net.ipv4.ip_forward = 1 and net.bridge.bridge-nf-call-iptables = 1 . Then run sudo sysctl -p to apply the changes. Finally, we need to install the container runtime. The most popular container runtime is containerd . Install containerd and enable it with these commands: sudo apt update , sudo apt install containerd , sudo systemctl enable containerd , and sudo systemctl start containerd . At this point, you should now have all the necessary packages and configurations for our Kubernetes cluster setup.

Now, let’s talk about the importance of each step. Disabling swap is vital because it can slow down your Kubernetes nodes, leading to performance issues. Kubernetes expects to have dedicated resources, and swap can interfere with this. Configuring iptables ensures that your containers can communicate with each other and the outside world, which is essential for your applications to function correctly. Finally, installing a container runtime like containerd is crucial. Kubernetes uses the container runtime to manage and run your containers. Without it, your cluster won’t be able to do anything. Taking these initial steps may seem tedious, but it will save you a lot of headaches down the line and ensure a stable and reliable cluster.

Step 2: Installing Kubernetes Components

Alright, now that we’ve got our machines prepped, it’s time to install the Kubernetes components . This involves installing kubeadm , kubelet , and kubectl . kubeadm is the command-line tool we’ll use to create and manage the cluster. kubelet is the node agent that runs on each machine and is responsible for managing pods and containers. And kubectl is the command-line tool that lets you interact with your cluster. We’ll start by adding the Kubernetes repository to our Ubuntu systems. This way, we can install the packages using apt . First, download the Kubernetes GPG key: sudo curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add - . Then, add the Kubernetes repository to your sources list: `sudo apt-add-repository