lxd from home:redwil:virt:deb:lxd-3.0.3 project

For xUbuntu 18.04 run the following:

Keep in mind that the owner of the key may distribute updates, packages and repositories that your system will trust (more information).

echo 'deb http://download.opensuse.org/repositories/home:/redwil:/virt:/deb:/lxd-3.0.3/xUbuntu_18.04/ /' | sudo tee /etc/apt/sources.list.d/home:redwil:virt:deb:lxd-3.0.3.list
curl -fsSL https://download.opensuse.org/repositories/home:redwil:virt:deb:lxd-3.0.3/xUbuntu_18.04/Release.key | gpg --dearmor | sudo tee /etc/apt/trusted.gpg.d/home_redwil_virt_deb_lxd-3.0.3.gpg > /dev/null
sudo apt update
sudo apt install lxd