How to install Kubernetes

In this tutorial, we will be installing Kubernetes (k8s) cluster. The cluster will have 1 master and 2 nodes.

Prerequisites

To complete this tutorial, we will need 3 nodes running Debian Stretch. This tutorial will work too on nodes running Ubuntu Xenial.

Node informations

node1 = k8s2001.tx.labnet = master node / IP address 10.64.0.14

node2 = k8s2002.tx.labnet / IP address 10.64.0.15

node3 = k8s2003.tx.labnet / IP address 10.64.0.16

make sure that all nodes can talk to each other. Like in all my turorials, I have a DHCP server and a DNS server running in my environment so no need for me to manually edit my /etc/hosts file. But, if you do not have a DHCP and DNS server in your environment, please edit your /etc/hosts file.

• master node

ppaul@k8s2001:~$ cat /etc/hosts
127.0.0.1	localhost
10.64.0.14	k8s2001.tx.labnet	k8s2001
# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

K8s Installation

Create a file called k8s_install.sh on all nodes and copy and paste the script below into the file.save the file and make the file executable. This script will install docker and K8s on all nodes

vi k8s_install.sh

#!/bin/bash
sudo swapoff -a
# Install Docker
sudo apt-get install apt-transport-https ca-certificates curl software-properties-common -y
sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg | apt-key add -
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/debian $(lsb_release -cs) stable"
sudo apt-get update -y
sudo apt-get install docker-ce -y
# Install kubernetes
sudo curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -
sudo echo 'deb http://apt.kubernetes.io/ kubernetes-xenial main' | sudo tee /etc/apt/sources.list.d/kubernetes.list
apt-get update -y
apt-get install kubelet kubeadm kubectl -y

If the installation complete with no problem, move the the next step to configure the master node.

K8s Configuration

All the configurations are done on the master node (k8s2001.tx.labnet). Once the configurations are done then we can move on to the other nodes to join them to the cluster.

On the master node

Login to your master node.This first step on configuring the master node is to initialize the cluster by using the master node IP address. The command is :

sudo kubeadm init --pod-network-cidr=192.168.0.0/16 --apiserver-advertise-address=10.64.0.14

You can use any given IP address for the pod-network-cider, I just pick 19.168.0.0/16. 10.64.0.14 is the IP address of the master node. After running the command you will have the output below.

Your Kubernetes master has initialized successfully!
To start using your cluster, you need to run the following 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
You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
 https://kubernetes.io/docs/concepts/cluster-administration/addons/
You can now join any number of machines by running the following on each node
as root:
 kubeadm join 10.64.0.14:6443 --token hfz0k8.aq3mjh0eng2nrlo5 --discovery-token-ca-cert-hash                                                                                                     
sha256:b9045fb51c6b177cbc58e19e1a193dd07131eb8f6b08d553d11c20b10f1e3295

The line in red is very important. You will be using this command to join the other nodes to the cluster. It is best to copy and save this line somewhere in case you need to join more node to the cluster.

As instructed by the output, we need to run the 3 comamnds below before we start using the cluster

mkdir -p $HOME/.kube

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

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

After running the 3 commands above, issue

kubectl get nodes 

Output

ppaul@k8s2001:~$ kubectl get node
NAME      STATUS     ROLES    AGE   VERSION
k8s2001   NotReady   master   10m   v1.12.2

We can see that the status of the master is NotReady. The reason being that the cluster doesn't have a Container Networking Interface or CNI. Issue the command below to deploy a Calico CNI.

kubectl apply -f https://docs.projectcalico.org/v3.3/getting-started/kubernetes/installation/hosted/calico.yaml

Output

ppaul@k8s2001:~$ sudo kubectl apply -f https://docs.projectcalico.org/v3.3/getting-started/kubernetes/installation/hosted/calico.yaml
configmap/calico-config created
secret/calico-etcd-secrets created
daemonset.extensions/calico-node created
serviceaccount/calico-node created
deployment.extensions/calico-kube-controllers created
serviceaccount/calico-kube-controllers created

Now issue again the command kubectl get nodes

ppaul@k8s2001:~$ kubectl get node
NAME      STATUS   ROLES    AGE   VERSION
k8s2001   Ready    master   18m   v1.12.2