---
upgrade:
  - |
    All supported operating systems now build their LXC images locally on the
    lxc container hosts rather than relying on external pre-built base images.
    debootstrap and dnf are used on debian and Centos variants respectively.
    All variables controlling the download of images have been removed from
    the lxc_hosts role, and a new override, lxc_apt_mirror is added to allow
    local mirrors to be specified for debootstrap. Centos systems will use
    the mirror configuration already present on the host when building
    the container rootfs with dnf.