Kubernetes

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Requirements

3 Ubuntu VMs having:

Same version
Having same resources
LAN Connectivity

Installing dependencies

The first thing you must do is install the necessary dependencies. This will be done on all machines that will join the Kubernetes cluster. The first piece to be install is apt-transport-https (a package that allows using https as well as http in apt repository sources). This can be installed with the following command:

sudo apt-get update && apt-get install -y apt-transport-https

Our next dependency is Docker. Our Kubernetes installation will depend upon this, so install it with:

sudo apt install docker.io

Once that completes, start and enable the Docker service with the commands

sudo systemctl start docker
sudo systemctl enable docker

Installing Kubernetes

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

Next add a repository by creating the file /etc/apt/sources.list.d/kubernetes.list and enter the following content:

deb http://apt.kubernetes.io/ kubernetes-xenial main 

Save and close that file. Install Kubernetes with the following commands:

apt-get update
apt-get install -y kubelet kubeadm kubectl kubernetes-cni

Initialize your master

With everything installed, go to the machine that will serve as the Kubernetes master and issue the command:

sudo kubeadm init

Before you join a node, you need to issue the following commands (as a regular user):

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

Deploying a pod network

You must deploy a pod network before anything will actually function properly.
Run kubectl apply -f [podnetwork].yaml with one of the options listed at:

https://kubernetes.io/docs/concepts/cluster-administration/addons/

Here we will be installing the Flannel pod network:

sudo kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
sudo kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/k8s-manifests/kube-flannel-rbac.yml

Issue the command

sudo kubectl get pods —all-namespaces

Joining a node

With everything in place, you are ready to join the node to the master. To do this, go to the node's terminal and issue the command:

sudo su
kubeadm join --token <TOKEN> <MASTER_IP:6443>

OR what ever is shown in the outputof master after kubeadm init:

kubeadm join 10.1.11.184:6443 --token 0lxezc.game230zg6jpa60g --discovery-token-ca-cert-hash sha256:74b34793d04696727b4dafe15ec82be3528f07af037c71e4a54e7475901bf627

Deploying a service

At this point, you are ready to deploy a service on your Kubernetes cluster. To deploy an NGINX service (and expose the service on port 80), run the following commands (from the master):

sudo kubectl run --image=nginx nginx-app --port=80 --env="DOMAIN=cluster"
sudo kubectl expose deployment nginx-app --port=80 --name=nginx-http

Go to your node and issue below command, you should see the service listed:

sudo docker ps -a,