Installing OKD on CentOS

Let’s see how to install OKD on a CentOS virtual machine !

What is OKD?

OKD is a distribution of Kubernetes optimized for continuous application development and multi-tenant deployment. OKD adds developer and operations-centric tools on top of Kubernetes to enable rapid application development, easy deployment and scaling, and long-term lifecycle maintenance for small and large teams. OKD is the upstream Kubernetes distribution embedded in Red Hat OpenShift.

Prerequisites

Swap should be disabled.

Creating the docker user

#!/bin/bash

function prerequisites(){
	if [ "$(id -u)" != "0" ]; then
		echo "This script must be run as root"
		exit 1
	fi
	
	[[ -z ${DOCKER_USER} ]] && { echo "DOCKER_USER is not set or empty"; exit 1; }
	[[ -z ${DOCKER_PASSWORD} ]] && { echo "DOCKER_PASSWORD is not set or empty"; exit 1; }
}

function create_user(){
	
	id -u ${DOCKER_USER} 2>&1 1>/dev/null
	
	if [ $? -ne 0 ] ; then
		# Adding docker user
		useradd ${DOCKER_USER}
		echo ${DOCKER_PASSWORD} | passwd --stdin ${DOCKER_USER}
	else
		echo "The user ${DOCKER_USER} already exist"
	fi
}

prerequisites
create_user

Updating CentOS virtual machine and install Docker

#!/bin/bash

function prerequisites(){
	if [ "$(id -u)" != "0" ]; then
		echo "This script must be run as root"
		exit 1
	fi
	
	[[ -z ${YUM_UPDATE} ]] && { echo "YUM_UPDATE is not set or empty"; exit 1; }
}

function install_docker(){
	
	if [ ${YUM_UPDATE} -eq 1 ] ; then
		yum -y update
	fi
	
	yum install -y yum-utils device-mapper-persistent-data lvm2 wget
	yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
	yum install -y  docker-ce docker-ce-cli containerd.io
}

prerequisites
install_docker

Configuring Docker

#!/bin/bash

function prerequisites(){
	if [ "$(id -u)" != "0" ]; then
		echo "This script must be run as root"
	fi
	
	[[ -z ${DOCKER_USER} ]] && { echo "DOCKER_USER is not set or empty"; exit 1; }
}

function configure_docker(){
	
	# Adding Docker user to docker group
	usermod -aG docker ${DOCKER_USER}
	
	# Creating docker directories
	mkdir -p /etc/docker /etc/containers
	
	tee /etc/containers/registries.conf<<EOF
[registries.insecure]
registries = ['172.30.0.0/16']
EOF

	tee /etc/docker/daemon.json<<EOF
{
   "insecure-registries": [
     "172.30.0.0/16"
   ]
}
EOF

	# Reloading and restarting Docker daemon
	systemctl daemon-reload
	systemctl restart docker

	# Enabling Docker to start at boot
	systemctl enable docker
}

prerequisites
configure_docker

Configuring firewall and network

#!/bin/bash

function prerequisites(){
	if [ "$(id -u)" != "0" ]; then
		echo "This script must be run as root"
		exit 1
	fi
}

function configure_firewall_and_network(){	
	# Enabling port forwarding
	tee -a /etc/sysctl.conf<<EOF
net.ipv4.ip_forward = 1
EOF
	sysctl -p

	# Configuring Firewalld
	DOCKER_BRIDGE=$(docker network inspect -f "{{range .IPAM.Config }}{{ .Subnet }}{{end}}" bridge)
	# Firewalld for dockerc zone (internal access)
	firewall-cmd --get-active-zones | grep dockerc 2>&1 1>/dev/null
	if [ $? -ne 0 ] ; then 
		firewall-cmd --permanent --new-zone dockerc
		firewall-cmd --permanent --zone dockerc --add-source ${DOCKER_BRIDGE}
		firewall-cmd --permanent --zone dockerc --add-port={80,443,8443}/tcp
		firewall-cmd --permanent --zone dockerc --add-port={53,8053}/udp
		# Firewalld for public zone (external access)
		firewall-cmd --permanent --zone public --add-port={80,443,8443}/tcp
		firewall-cmd --reload
	fi
}

prerequisites
configure_firewall_and_network

Installing OpenShift

#!/bin/bash

function prerequisites(){
	if [ "$(id -u)" != "0" ]; then
		echo "This script must be run as root"
		exit 1
	fi
}

function install_openshift(){
	if [ "$(id -u)" != "0" ]; then
		echo "This script must be run as root"
	fi
	
	if [ ! -z ${OPENSHIFT_LOCAL_ARCHIVE} ] ; then
		OPENSHIFT_ARCHIVE_NAME=$(basename ${OPENSHIFT_LOCAL_ARCHIVE})
		if [ ! -f "${OPENSHIFT_ARCHIVE_NAME}" ] ; then
			if [ ! -f "${OPENSHIFT_LOCAL_ARCHIVE}" ] ; then
				wget -O ${OPENSHIFT_ARCHIVE_NAME} ${OPENSHIFT_GITHUB_ARCHIVE}
			else
				cp -f ${OPENSHIFT_LOCAL_ARCHIVE} ${OPENSHIFT_ARCHIVE_NAME}
			fi
		fi
		
		tar xvf ${OPENSHIFT_ARCHIVE_NAME}
		cd openshift-origin-client*/
		mv oc kubectl /usr/local/bin/
	else
		yum -y install centos-release-openshift-origin
		yum -y install origin-clients
	fi
}

prerequisites
install_openshift

Configuring OpenShift

This script must be executed as non-root user. Because I ran this script many times, my download speed from docker was really slow. I saved the OpenShift docker images locally (using docker save myimage:latest | gzip > myimage_latest.tar.gz for each OpenShift required image) and, when installing the virtual machine again, I directly loaded OpenShift images to my local docker instance (using docker load -i myimage_latest.tar.gz).

#!/bin/bash

function prerequisites(){
	cd ~
	
	oc version 2>&1 1>/dev/null
	if [ $? -ne 0 ] ; then
		echo "OpenShift is not installed... Exiting"
		exit 1
	fi
	
	[[ -z ${ETH_INTERFACE_NAME} ]] && { echo "ETH_INTERFACE_NAME is not set or empty"; exit 1; }
	
	export ETH_INTERFACE_IP=$(ip -4 addr show ${ETH_INTERFACE_NAME} | grep -Po 'inet \K[\d.]+')
}

function configure_openshift(){

	# Installing Docker images from tar.gz archives
	if [ -d ${OPENSHIFT_DOCKER_ARCHIVES} ] ; then
	
		# Loading OpenShift images to Docker
		find ${OPENSHIFT_DOCKER_ARCHIVES} -type f -name "openshift_origin*.tar.gz" -exec docker load -i  {} \;
	fi
	
	# Starting OpenShift Origin local cluster
	oc cluster up --public-hostname=${ETH_INTERFACE_IP} --routing-suffix=${ETH_INTERFACE_IP}.xip.io
}

prerequisites
configure_openshift

Accessing the console

After the “oc cluster up” command, the console output should indicate how to connect to the OKD console.

When connecting to https://192.168.99.111:8443/console using my web browser, the console is displayed, allowing me to enter my credentials.

Let’s try to connect with “Romain” as username and “mysecretpassword” as password.

YES ! I’m able to connect to my OpenShift platform with my new credentials. To be sure that all is working fine, create a new project and try to deploy an app (I tried with “Apache HTTP Server”). After some network configuration to resolve the httpd route, httpd home page is displayed.

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What is OKD?