KVM Guest Operating System

The KVM Guest is a sparse installation.

KVM Guest Template

Install Debian

Define your disk layout, then go ahead and install Debian. Make sure this is an installation with a minimum of packages. Once Debian has been installed, leave the template alone.

On a fresh minimal installation, not much diskspace is used.

Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg1-root  1,9G  791M  954M   46% /
/dev/vda1             243M   53M  162M   25% /boot

KVM Guest Clone

Clone Your Template

Start by cloning your template.

Configure the New Guest

Root Password

Reset your root passwd.

passwd

Hostname

Your new system will need a new hostname.

• /etc/hostname
• /etc/hosts

sed -i 's/stretch-template/clone/g' /etc/hosts
sed -i 's/stretch-template/clone/g' /etc/hostname

Unique sshd keys

Make sure your clone does indeed have unique ssh keys. This is a really important step when cloning. Consider all your clones had the same ssh keys, that would really be a mess.

rm /etc/ssh/ssh_host_*
dpkg-reconfigure openssh-server
service sshd restart

Update

Make sure downloaded .deb files are removed after they have been installed.

echo "APT::Keep-Downloaded-Packages \"false\";" > /etc/apt/apt.conf.d/01keep-debs

Since the template can be quite old, you might as well update the new system.

apt-get update
apt-get upgrade