Incus 2-minute quick install on Ubuntu
Incus
is a LXD fork which I recommend due to its more liberal license. See LXD has been re-licensed and is now under a CLA for more info.
Installing & configuring it on Ubuntu is easy:
sudo apt -y install incus qemu-system
sudo usermod -aG incus $USER
sudo usermod -aG incus-admin $USER
Now logout and log back in so that group change takes effect!
incus admin init --auto --storage-backend dir
Distilled from the official Incus installation page