How to install Kubernetes (K8S)

The first thing that we are going to do is use SSH to log in to all machines. Once we have logged in, we need to elevate privileges using sudo.

  sudo su 

Disable SELinux

setenforce 0

sed -i --follow-symlinks 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/sysconfig/selinux

Enable the br_netfilter module for cluster communication.

modprobe br_netfilter

echo '1' > /proc/sys/net/bridge/bridge-nf-call-iptables

Disable swap to prevent memory allocation issues.

swapoff -a

vim /etc/fstab.orig -> Comment out the swap line

Install the Docker prerequisites.

yum install -y yum-utils device-mapper-persistent-data lvm2

Add the Docker repo and install Docker.

yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo

yum install -y docker-ce

Configure the Docker Cgroup Driver to systemd, enable and start Docker

sed -i '/^ExecStart/ s/$/ --exec-opt native.cgroupdriver=systemd/' /usr/lib/systemd/system/docker.service 

systemctl daemon-reload

systemctl enable docker --now 

systemctl status docker

docker info | grep -i cgroup

Add the Kubernetes repo.

cat <<EOF > /etc/yum.repos.d/kubernetes.repo

[kubernetes]

name=Kubernetes

baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64

enabled=1

gpgcheck=0

repo_gpgcheck=0

gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg

     https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg

EOF

Install Kubernetes.

yum install -y kubelet kubeadm kubectl

Enable Kubernetes. The kubelet service will not start until you run kubeadm init.

systemctl enable kubelet

*Note: Complete the following section on the MASTER ONLY!

Initialize the cluster using the IP range for Flannel.

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

Copy the kubeadmin join command.

Exit sudo and run the following:

mkdir -p $HOME/.kube

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

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

Deploy Flannel.

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

Check the cluster state.

kubectl get pods --all-namespaces

*Note: Complete the following steps on the NODES ONLY!

Run the join command that you copied earlier (this command needs to be run as sudo), then check your nodes from the master.

kubectl get nodes

Thanks!