How to Install Kubernetes on Ubuntu

Kubernetes is a portable, extensible, open-source platform for managing containerized workloads and services, that facilitates both declarative configuration and automation. It has a large, rapidly growing ecosystem. Kubernetes services, support, and tools are widely available.

The name Kubernetes originates from Greek, meaning helmsman or pilot. Google open-sourced the Kubernetes project in 2014. Kubernetes builds upon a decade and a half of experience that Google has with running production workloads at scale, combined with best-of-breed ideas and practices from the community.

In this tutorial, we are going to show you how to install Kubernetes and configure it on the Ubuntu system. For this tutorial you will need two Ubuntu nodes (machines) with the following minimum configurations:

• Node 1: Will be a master node (CPU of 2 Cores, 2 GB RAM).
• Node 2: Will be a slave node (CPU of 1 Core, 1GB RAM).

Before starting the installation process, you will need to ensure that your machine is updated. You can use the following commands:

sudo apt-get update

sudo apt-get upgrade

sudo apt-get dist-upgrade

Set hostname for your Nodes

Step 1. On your master node, use the following command:

sudo hostnamectl set-hostname kubernetes-master

Step 2. On your slave node, use the following command:

sudo hostnamectl set-hostname kubernetes-slave

It’s highly recommended for both the nodes to have an accurate time and date to get valid TLS certificates.

Docker Installation

Perform the following steps on Master as well as slave.

Step 1. Install Docker using the following command.

sudo apt install docker.io

Step 2. Verify your installation you can use:

docker --version

Step 3. By default, the docker service is not enabled. So, once the installation completes successfully, execute the following command on both nodes to enable the docker service.

sudo systemctl enable docker

Kubernetes Installation

Perform the following steps on Master as well as slave.

Step 1. Install curl package using the next command.

sudo apt install curl

Step 2. Add the Kubernetes signing key.

curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add

Step 3. Add the Kubernetes repository.

sudo apt-add-repository "deb http://apt.kubernetes.io/ kubernetes-xenial main"

Note that at the time of writing this tutorial only the Xenial Kubernetes repository is available so it will be the one we will use for our installation.

Step 4. Verify your installation, use the command:

kubeadm version

Step 5. Before installing Kubernetes, make sure that your system is not using the swap memory because Kubernetes will refuse to operate if your Ubuntu is using the swap memory.

Disable the swap memory:

sudo swapoff -a

Step 6. Install Kubernetes.

sudo apt install kubeadm

Kubernetes Master Server Initialization

Step 1. On your master node, use the next command to initialize the Kubernetes master node.

sudo kubeadm init --pod-network-cidr=10.244.0.0/16

Take a copy from the last line “kubeadm join 10.0.2.15:6443 –token edvbbv.51hy5e2hgaxr1b4h –discovery-token-ca-cert-hash sha256:01db7c5913e363c099dc7a711550b8399c41f7cc92bda6b5ff06d6b8382a73e2” in the previous screenshot as we will be using it in the slave node to make it join the cluster.

Step 2. Also, as per the previous output its recommended to use the following commands to start using the Kubernetes cluster.

mkdir -p $HOME/.kube

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

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

Pod Network Deployment

To enable communication between cluster nodes, we have to deploy a pod network.

Step 1.  On master node, use the following command to deploy a pod network.

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

Step 2.  On the master node, ensure that everything is up and running.

kubectl get pods --all-namespaces

Join the Kubernetes Cluster

For now, everything should be ready for the master and slave nodes to join the Kubernetes Cluster.

Step 1. On the slave node and to let the slave node join the cluster, use the command copied earlier from the output of Kubernetes initialization step, which should look something like this:

sudo kubeadm join 10.0.2.15:6443 --token edvbbv.51hy5e2hgaxr1b4h --discovery-token-ca-cert-hash sha256:01db7c5913e363c099dc7a711550b8399c41f7cc92bda6b5ff06d6b8382a73e2

Step 2. On the master node, check if the slave node has joined the cluster:

kubectl get nodes

Congratulations, you just have created the Kubernetes cluster and everything should be ready to move on and deploy any service you need (like Apache container or Nginx server) to start using your cluster.