Centos 6.5 - Install OpenVZ

Introduction

OpenVZ has a couple of advantages over Xen. It has proved easier to set up the host so far and pretty quick to set up each virtual machine (no need to run an install process and worry about who/where/how the domU’s kernels are booting). The main advantage that I have read about so far is the ability to set allocated memory on openvz and not allow clients to spill out into swap space which kills disk IO for everyone else (which can happen in Xen). It is not a ‘true’ hypervisor (and thus cannot run windows), but has less overheads and is extremely fast and efficient.

Install Script

Copy and paste the following script into a file and execute it. Read all the output/echo statements if you want to know what it's doing.

#!/bin/bash

# BASH guard
if ! [ -n "$BASH_VERSION" ];then
    echo "this is not bash, calling self with bash....";
    SCRIPT=$(readlink -f "$0")
    /bin/bash $SCRIPT
    exit;
fi

clear
echo 'Installing OpenVZ...'

echo "updating..."
yum update -y

echo 'installing wget...'
yum install wget -y

echo 'Adding openvz Repo...'
cd /etc/yum.repos.d
wget http://download.openvz.org/openvz.repo
rpm --import http://download.openvz.org/RPM-GPG-Key-OpenVZ

echo 'Installing OpenVZ Kernel...'
yum install -y vzkernel

echo 'Installing additional tools...'
yum install vzctl vzquota ploop -y

echo 'Changing around some config files..'
sed -i 's/kernel.sysrq = 0/kernel.sysrq = 1/g' /etc/sysctl.conf

echo "Setting up packet forwarding..."
sed -i 's/net.ipv4.ip_forward = 0/net.ipv4.ip_forward = 1/g' /etc/sysctl.conf

# With vzctl 4.4 or newer there is no need to do manual configuration. Skip to #Tools_installation.
# source: http://openvz.org/Quick_installation
#echo 'net.ipv4.conf.default.proxy_arp = 0' >> /etc/sysctl.conf
#echo 'net.ipv4.conf.all.rp_filter = 1' >> /etc/sysctl.conf
#echo 'net.ipv4.conf.default.send_redirects = 1' >> /etc/sysctl.conf
#echo 'net.ipv4.conf.all.send_redirects = 0' >> /etc/sysctl.conf
#echo 'net.ipv4.icmp_echo_ignore_broadcasts=1' >> /etc/sysctl.conf
#echo 'net.ipv4.conf.default.forwarding=1' >> /etc/sysctl.conf


echo "Allowing multiple subnets to reside on the same network interface..."
sed -i 's/#NEIGHBOUR_DEVS=all/NEIGHBOUR_DEVS=all/g' /etc/vz/vz.conf
sed -i 's/NEIGHBOUR_DEVS=detect/NEIGHBOUR_DEVS=all/g' /etc/vz/vz.conf

echo "Setting container layout to default to ploop (VM in a file)..."
sed -i 's/#VE_LAYOUT=ploop/VE_LAYOUT=ploop/g' /etc/vz/vz.conf

echo "Setting Ubuntu 12.04 64bit to be the default template..."
sed -i 's/centos-6-x86/ubuntu-12.04-x86_64/g' /etc/vz/vz.conf

echo 'Purging your sys configs...'
sysctl -p

echo "Disabling selinux..."
sed -i 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/sysconfig/selinux

echo "disabling iptables..."
/etc/init.d/iptables stop && chkconfig iptables off

clear

echo "OpenVZ Is now Installed. "
echo "Please reboot into the openvz kernel to start using it."
echo "Programster"

This script was last tested on the 15th August 2014

Start Your First Container

Create a virtual machine with a command like such (I build command in an sh file before running)

vzctl create $unique-id-for-vm \ --ostemplate $template-name-here \ --conf $configuration-name-here \ --ipadd $ip-address-of-vm \ --onboot yes \ --hostname $hostname-of-vm

Here is an example already filled out:

vzctl create 101 \
--ostemplate centos-6-x86_64 \
--conf basic \
--ipadd 192.168.1.43 \
--hostname centos1

OR

vzctl create 101 \
--ostemplate ubuntu-14.04-x86_64 \
--conf basic \
--ipadd 192.168.1.43 \
--hostname ubuntu1

The root password will be the same as the host machine unless you change it using passwd inside the machine, or by issuing the following command:
vzctl set {CTID} --userpasswd {user}:{password} --save
To start the virtual machine that you have created, run:
vzctl start
The machine could automatically connect to google dns (8.8.8.8) but had to manually set nameserver.
echo nameserver 8.8.8.8 > /etc/resolv.conf
Restart the network for the nameserver to take effect:
service network restart

References

• Installing And Using OpenVZ On CentOS 6.0
• Install Script (Centos 64bit)
• Setting up Iptables for OpenVZ
• OpenVZ wiki