$ vagrant plugin list
$ dnf install vagrant vagrant-libvirt
$ vagrant plugin list
$  (NOT GOOD) vagrant plugin install vagrant-libvirt

# --------------------------------------------------------------------------------

$ vagrant box add generic/rocky8 --provider=libvirt

# --------------------------------------------------------------------------------

$ vagrant box add generic/rocky8
==> box: Loading metadata for box 'generic/rocky8'
    box: URL: https://vagrantcloud.com/generic/rocky8
This box can work with multiple providers! The providers that it
can work with are listed below. Please review the list and choose
the provider you will be working with.

1) hyperv
2) libvirt
3) parallels
4) virtualbox
5) vmware_desktop

Enter your choice: 2
==> box: Adding box 'generic/rocky8' (v3.4.0) for provider: libvirt
    box: Downloading: https://vagrantcloud.com/generic/boxes/rocky8/versions/3.4.0/providers/libvirt.box
    box: Calculating and comparing box checksum...
==> box: Successfully added box 'generic/rocky8' (v3.4.0) for 'libvirt'!

#
$ ls -l ~/.vagrant.d/boxes/generic-VAGRANTSLASH-rocky8/3.4.0/libvirt/
total 1029128
-rw-rw-r-- 1 hyung-hwan hyung-hwan 1053807104 Aug 29 09:41 box.img
-rw-rw-r-- 1 hyung-hwan hyung-hwan        301 Aug 29 09:41 info.json
-rw-rw-r-- 1 hyung-hwan hyung-hwan         59 Aug 29 09:41 metadata.json
-rw-rw-r-- 1 hyung-hwan hyung-hwan       1987 Aug 29 09:41 Vagrantfile