Tip: Create a libvirt guest using virt-builder

virt-builder and virt-install together make it easy to create libvirt guests in just a few minutes.

Before you start, read the installation notes for the OS you’re about to install. They may contain essential tips for a successful installation:

$ virt-builder --notes ubuntu-13.10
[...]

Note I’m running this as root, but that’s only necessary because I want to write the guest to a logical volume. Normally you don’t (and shouldn’t) run virt-builder as root.

# lvcreate -L 50G -n builder-ubuntu1310 /dev/vg_data
# virt-builder ubuntu-13.10 \
    --output /dev/vg_data/builder-ubuntu1310 \
    --hostname builder-ubuntu1310 \
    --install build-essential,debhelper
[   0.0] Downloading: http://libguestfs.org/download/builder/ubuntu-13.10.xz
[   1.0] Uncompressing: http://libguestfs.org/download/builder/ubuntu-13.10.xz
[  23.0] Running virt-resize to expand the disk
[  99.0] Opening the new disk
[ 103.0] Setting a random seed
[ 103.0] Setting the hostname: builder-ubuntu1310
[ 103.0] Random root password: mOQ8YdwKuxkMlpOU [did you mean to use --root-password?]
[ 103.0] Installing packages: build-essential debhelper
[ 423.0] Finishing off
Output: /dev/vg_data/builder-ubuntu1310
Total usable space: 48.2G
Free space: 47.1G (97%)
# virt-install --import \
    --name builder-ubuntu1310 --ram 4096 \
    --disk path=/dev/vg_data/builder-ubuntu1310,format=raw

(Yes, I forgot to use the --root-password option …)