kvm & systemd

Networking

Virtual switch for the virtual machines - vde2 + brctl

apt-get install bridge-utils qemu-system-x86 vde2 uml-utilities socat net-tools

edit /etc/network/interfaces

auto tap9
iface tap9 inet static
        address 0.0.0.0
        tunctl_user uml-net

auto br0
iface br0 inet dhcp
  bridge_ports eth0 tap9
  bridge_fd 0
  bridge_stp off

create /etc/systemd/system/vde_switch_internal.service

[Unit]
Description=vde switch for internal connections
After=networking.service
Wants=networking.service

[Service]
Type=forking
PIDFile=/run/vde_switch/vde_c.pid
Restart=always
RestartSec=3s
User=uml-net
ExecStartPre=+/usr/bin/install -o uml-net -g uml-net -d /run/vde_switch
ExecStart=/usr/bin/vde_switch -sock /run/vde_switch/vde_c.ctl -tap tap9 --daemon --pidfile /run/vde_switch/vde_c.pid --mode 0770

[Install]
WantedBy=multi-user.target

then systemctl start vde_switch_internal

create /usr/bin/kvm-stop-guest

#!/bin/bash

if [ "$1" == "" ]; then
	echo need one argument - guest name
	exit 1
fi

MON_FILE="/run/qemu-monitor-socket_$1"

if [ ! -e $MON_FILE ]; then
	echo $1 not running? $MON_FILE not present
	exit 0
fi

echo shutting down $1 via $MON_FILE

echo "system_powerdown" | socat - unix-connect:$MON_FILE
while [ -e $MON_FILE ]; do
	echo waiting for termination
	sleep 5
done

lvcreate -L 10G -n HNAME vg0 disk image using LVM or dd if=/dev/zero of=/srv/HNAME.img bs=1G count=10 disk image using file.

create /etc/systemd/system/kvm-HNAME.service, replace HNAME, in service name and 2x inside service, for name/hostname of the guest machine

[Unit]
Description=kvm machine
After=network-online.target
Wants=network-online.target

[Service]
Environment=SN=HNAME
Environment=DISKFN=/dev/vg0/HNAME
Environment=MACADDR=52:54:00:00:00:01
Environment=SPORT=6900
Environment=SPW=SUPERSECRET
Environment=BOOTCDIMG=/var/tmp/debian-11.2.0-amd64-netinst.iso
Type=simple
Restart=no
User=root
ExecStart=kvm -drive file=${DISKFN},format=raw,index=0,media=disk -m 1024 -smp 2 -cpu host -name ${SN},process=${SN} -machine type=pc,accel=kvm -monitor unix:/run/qemu-monitor-socket_${SN},server,nowait -net nic,macaddr=${MACADDR} -net vde,sock=/run/vde_switch/vde_c.ctl -vga qxl -spice port=${SPORT},password=${SPW} -display none -boot d -cdrom ${BOOTCDIMG}
ExecStop=/usr/bin/kvm-stop-guest ${SN}
TimeoutStopSec=60s

[Install]
WantedBy=multi-user.target

systemctl start kvm-HNAME and connect to the machine using spicy --uri spice://localhost:6900

once system is installed, remove -boot d -cdrom ${BOOTCDIMG} from service file, reload systemctl and enable both vde_switch_internal and kvm-HNAME to start on system start up.