boxes:
  ubuntu:
    "20.04":
      virtualbox: ubuntu/focal64
    "18.04":
      virtualbox: ubuntu/bionic64
      libvirt: generic/ubuntu1804
    "16.04":
      virtualbox: ubuntu/xenial64
      libvirt: yk0/ubuntu-xenial
  centos:
    stream8:
      virtualbox: centos/stream8