Simple Virtual Appliances with Linux and Xen

# Kickstart Configuration for MINIMAL CENTOS
install
text
reboot

url --url http://mirror.centos.org/centos/5.3/os/i386/
lang en_US.UTF-8
langsupport --default=en_US.UTF-8 en_US.UTF-8
keyboard us

skipx
network --device eth0 --bootproto dhcp

# The password is "password"
rootpw --iscrypted $1$h5ebo1pm$OHL3De9oalNzqIG1BUyJp0
firewall --disabled
selinux --permissive
authconfig --enableshadow --enablemd5
timezone America/New_York

bootloader --location=mbr
clearpart --all --initlabel
part /boot --fstype ext3 --size=100
part pv.2 --size=0 --grow
volgroup VolGroup00 --pesize=32768 pv.2
logvol /    --fstype ext3 --name=LogVol00 \
            --vgname=VolGroup00 --size=1024 --grow
logvol swap --fstype swap --name=LogVol01 \
            --vgname=VolGroup00 --size=256
%packages --nobase
coreutils
yum
rpm
e2fsprogs
lvm2
grub
sysstat
ntp
openssh-server
openssh-clients
%post

Now, all you have to do is boot up the Xen guest and watch your appliance's OS install. The install will be fully automated; simply execute the following command and sit back:

xenhost$ xm create -c /xen/appliance-base/appliance-base.install.cfg

After the install completes, it will shut down the Xen guest and drop back to a shell prompt. Next, still in the same directory, create an appliance-base.cfg, as shown in Listing 3, which will be used to run the appliance in normal mode.

# Xen Configuration for appliance-base
name   = "appliance-base"
memory = "256"
disk   = ['tap:aio:/xen/appliance-base/appliance-base.img,xvda,w',]
vif    = ['bridge=xenbr0,mac=00:16:3e:00:00:01',]
vcpus  = 1

bootloader ="/usr/bin/pygrub"
on_reboot  = 'restart'
on_crash   = 'restart'

Boot up the Xen guest again using the new config:

xenhost$ xm create -c /xen/appliance-base/appliance-base.cfg

And now, you're ready to start installing services.

Let's get this guest ready to be an appliance. When the guest is completely booted, log in as root. The password is “password” (this is somewhat of a de facto standard for virtual appliances). Execute the following commands to update fully; then, install Webmin and all its dependencies:

appliance-base# wm=http://sourceforge.net/projects/webadmin/files
appliance-base# yum -y update
appliance-base# yum -y install perl wget
appliance-base# wget $wm/webmin/webmin-1.480-1.noarch.rpm/download
appliance-base# rpm -Uvh webmin-1.480-1.noarch.rpm
appliance-base# chkconfig webmin on

Finally, add the following snippet of code to the bottom of the /etc/rc.local file:

appliance-base# echo "" >> /dev/console
appliance-base# echo "" >> /dev/console
appliance-base# echo "Connect to WEBMIN at: http://$(ifconfig eth0 |
                         grep 'inet addr:' |
                         awk '{ print $2; }' |
                         cut -d: -f2):10000/" >> /dev/console
appliance-base# echo "" >> /dev/console
appliance-base# echo "" >> /dev/console

This will output the current IP address for eth0 to tell the user how to connect to Webmin for the first time. This, of course, assumes that the appliance is booting up on a DHCP network. Often a virtual appliance is booted initially with DHCP and then configured via the Web with a static address.

At this point, we have a generic virtual appliance ready to customize. To make a MySQL server appliance, run yum install mysql-server. To make a DNS appliance, run yum install bind bind-utils. To make a LAMP appliance, run yum install httpd php mysql-server. Reboot, or click Refresh Modules inside Webmin, and you will be presented with Web management for whatever you installed. Webmin supports a very wide range of software right out of the box, and even more with extension modules available on the Webmin Web site.

For our example, let's make a simple MySQL database server appliance. To customize your base appliance, run the following commands inside the VM:

appliance-base# yum -y install mysql-server
appliance-base# /etc/init.d/mysqld start
Initializing MySQL database:  Installing MySQL system tables...
OK
appliance-base# mysql_secure_installation

NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MySQL
      SERVERS IN PRODUCTION USE!  PLEASE READ EACH STEP CAREFULLY!

Enter current password for root (enter for none):
OK, successfully used password, moving on...

Setting the root password ensures that nobody can log into the MySQL
root user without the proper authorization.

Set root password? [Y/n] Y
New password: password
Remove anonymous users? [Y/n] Y
Disallow root login remotely? [Y/n] n
Remove test database and access to it? [Y/n] Y
Reload privilege tables now? [Y/n] Y

All done! If you've completed all of the above steps, your MySQL
installation should now be secure.

Thanks for using MySQL!