KVM // Debian/Ubuntu

assuming the host is up and running already

warning: Ubuntu is more painful than Debian in this case – choose Debian

With virt-install

guest=focal
guest=buster

country=fr
country=ru

mkdir -p /data/guests/$guest/
cd /data/guests/$guest/

osinfo-query os | grep ubuntu | sort -k3 -t'|' -V
osinfo-query os | grep debian | sort -k3 -t'|' -V
grep short-id /usr/share/osinfo/os/ubuntu.com/ubuntu-20*.xml
grep short-id /usr/share/osinfo/os/debian.org/debian-10*.xml

virt-install --name $guest --vcpus 12 --ram 1024 \
--disk path=/data/guests/$guest/$guest.qcow2,size=26,bus=virtio \
--network bridge=virbr0,model=virtio \
--graphics none --accelerate \
--console pty,target_type=serial --extra-args 'console=ttyS0,115200n8 serial' \

# ubuntu
--os-type linux --os-variant ubuntu20.04 \
--location http://$country.archive.ubuntu.com/ubuntu/dists/$guest/main/installer-amd64/

# debian
--os-type linux --os-variant debian10 \
--location http://deb.debian.org/debian/dists/buster/main/installer-amd64/

eventually use generic because lastest distro releases are not always available within osinfo-db

# --os-type linux --os-variant generic \

choose locale, mirror and timezone accordingly, and select those package groups during the installation process

# ubuntu
basic ubuntu server
openssh server

# debian
ssh server
standard system utilities

once the machine reboots, either it’s an Ubuntu and you need to escape the empty console and shutdown the guest – ideally even before it reboots

ctrl-]
reset
virsh shutdown focal
virsh list --all

or it’s a Debian and you’re good already, there was no kernel messages but you got the prompt.

Ubuntu-specific fixup

you need to fix GRUB setup for talking to the serial console

mkdir -p /data/guests/$guest/lala/
cd /data/guests/$guest/

guestmount --help
guestmount --domain $guest --inspector lala/
# --rw

grub-update will complain, even if you mount /dev/ and everything, because the /dev/vda device is unknown to the chroot

grub-probe: error: unknown filesystem.

hence fix grub.cfg manually and like a dirty bastard

cp -pi lala/boot/grub/grub.cfg lala/boot/grub/grub.cfg.dist
vi lala/boot/grub/grub.cfg

(search for vmlinuz)
... console=ttyS0,19200 earlyprint=serial,ttyS0,115200

guestunmount lala/

and eventually do it properly once the guest has booted

virsh start $guest --console

cp -pi /etc/default/grub /etc/default/grub.dist
vi /etc/default/grub

GRUB_DEFAULT=0
#GRUB_TIMEOUT_STYLE=hidden
GRUB_TIMEOUT=3
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT=""
GRUB_CMDLINE_LINUX="console=tty0 console=ttyS0,115200n8 netcfg/do_not_use_netplan=true net.ifnames=0 biosdevname=0 mitigations=off"

and note this is already there

GRUB_TERMINAL=serial
GRUB_SERIAL_COMMAND="serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1"

apply

update-grub
sync

Debian-specific fixup

The kernel messages were missing on the serial console

cp -pi /etc/default/grub /etc/default/grub.dist
vi /etc/default/grub

GRUB_DEFAULT=0
GRUB_TIMEOUT=3
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT=""
GRUB_CMDLINE_LINUX="console=tty0 console=ttyS0,115200n8 net.ifnames=0 biosdevname=0 mitigations=off"

and note this is already there

GRUB_TERMINAL=serial
GRUB_SERIAL_COMMAND="serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1"

apply

update-grub
sync

Ready to go

cat /sys/devices/system/clocksource/clocksource0/available_clocksource
cat /sys/devices/system/clocksource/clocksource0/current_clocksource

passwd -d root
userdel -r nouser

mkdir .ssh/
vi .ssh/authorized_keys

(deploy your SSH pubkey over there)

chmod 700 .ssh/
chmod 600 .ssh/authorized_keys

cd /etc/
ln -sf ../usr/share/zoneinfo/Europe/Moscow
echo Europe/Moscow > timezone

ln -sf ../usr/share/zoneinfo/Europe/Paris
echo Europe/Paris > timezone

apt update
apt install ifupdown net-tools

rmdir /etc/network/interfaces.d/
vi /etc/network/interfaces

auto lo
iface lo inet loopback

allow-hotplug eth0
iface eth0 inet dhcp

allow-hotplug eth1
iface eth1 inet manual

poweroff

Operations

poweroff

virsh start $guest --console
#virsh console $guest

GNS3-ready

eventually make it available for GNS3

With ubuntu-vm-builder

draft

ubuntu-vm-builder kvm xenial --name guestbuilder --libvirt qemu:///system
# --components 'main,universe,restricted'
tail -F /tmp/tmpARZ01Y

With uvtool

apt install uvtool
uvt-simplestreams-libvirt sync release=xenial arch=amd64
uvt-simplestreams-libvirt sync release=artful arch=amd64

it wants an RSA key pair, not ECDSA or what ever is much better, so let us give this crappy tool some slack,

ssh-keygen

and finally run a guest,

uvt-kvm create guestuvt
uvt-kvm list
virsh list

and access it,

uvt-kvm ssh guestuvt

Resources

https://cloud-images.ubuntu.com/artful/current/

https://www.cyberciti.biz/faq/how-to-use-kvm-cloud-images-on-ubuntu-linux/

https://help.ubuntu.com/lts/serverguide/cloud-images-and-uvtool.html