How to deploy Kubernetes cluster with Ubuntu

OS used Ubuntu 18.04 LTS

This is 3 node cluster setup implementations with the following sub-services

Kube Master – Docker, Kubeadm, Kubelet, kubectl, Control Plane

Kube node 1 – Docker, Kubeadm, Kubelet, kubectl

Kube node 2 – Docker, Kubeadm, Kubelet, kubectl

Docker is the container runtime that we will be using. The first step in building out the cluster is to install docker on all three servers.

Add the Docker repository GPG key :

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add –

Add the Docker repository :

sudo add-apt-repository \ "deb [arch=amd64] https://download.docker.com/linux/ubuntu \ $(lsb_release -cs) \ stable"

Reload the apt source list :

sudo apt-get update

Install Docker :

sudo apt-get install -y docker-ce=18.06.1~ce~3-0~ubuntu

Prevent auto-updates for the docker packages :

sudo apt-mark hold docker-ce

You can verify that docker is working by running this command:

sudo docker version

Install Kubeadm, kubelet and kubectl

Kubeadm – This is a tool that automate a large portion of the process of setting up a cluster. It will make our job much easier.

Kubelet – the essential running containers on a node. Every server that will be running containers needs kubelet.

Kubectl – command-line tool for interface with cluster once it is up. This used to manage the cluster.

Install kubeadm, kubelet and kubectl on all three servers :

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

Adding Kubernetes repositories :

cat << EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list deb https://apt.kubernetes.io/ kubernetes-xenial main EOF

Reload the apt source list :

sudo apt-get update

Install packages :

sudo apt-get install -y kubelet=1.15.7-00 kubeadm=1.15.7-00 kubectl=1.15.7-00
sudo apt-mark hold kubelet kubeadm kubectl

After installing these components, verify that Kubeadm is working by getting the version info :

kubeadm version

Bootstrapping the cluster

Use kubeadm to build the cluster

Initialized the cluster on the Kube Master server

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

pod network cidr required later for the flannel networking plugin

setup kubeconfig for the local user on the Kube Master Server

mkdir -p $HOME/.kube 
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config 
sudo chown $(id -u):$(id -g) $HOME/.kube/config

Verify that the cluster is responsive and that Kubectl is working

kubectl version

Kubeadm init command should output a kubeadm join command containing a token and hash. Copy that command and run it with sudo on both worker nodes. It should look something like this

sudo kubeadm join $some_ip:6443 --token $some_token --discovery-token-ca-cert-hash $some_hash

Verify that all nodes have successfully joined the cluster :

kubectl get nodes

Configure networking with Flannel

Kubernetes supports a variety of networking solutions to provide networking between containers

On all three nodes, run the following:

echo "net.bridge.bridge-nf-call-iptables=1" | sudo tee -a /etc/sysctl.conf 
sudo sysctl -p

Install Flannel in the cluster by running this only on the Master node:

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/bc79dd1505b0c8681ece4de4c0d86c5cd2643275/Documentation/kube-flannel.yml

Verify that all the nodes now have a STATUS of Ready :

kubectl get nodes

Note: It may take a few moments for all nodes to enter the Ready status, so if they are not all Ready , wait a few moments and try again