VM Ubuntu 18.04 with a complete GUI.

How to use Vagrant you can find here. To start VM:

vagrant up
vagrant reload

When the VM is configured, the VM screen should show the LightDM login screen. Log in as user "vagrant", password "vagrant". Open terminal and type:

# Virtual box configuration
sudo VBoxClient --clipboard
sudo VBoxClient --draganddrop
sudo VBoxClient --display
sudo VBoxClient --checkhostversion
sudo VBoxClient --seamless

reboot

After reboot, VM is ready to use.