Lucas Gomes (from the Red Hat OpenStack Ironic team) recently pointed out to me that modern Anaconda supports formatting a system based on a squashfs image: https://github.com/rhinstaller/anaconda/blob/master/pyanaconda/packaging/livepayload.py (This capability appears to be part of the way provisioning from a LiveUSB/LiveCD works)

Over on kickstart-list, Gene Czarcinski describes a way to get that working from a kickstart file: https://www.redhat.com/archives/kickstart-list/2014-November/msg00004.html

And then also added that to the Fedora wiki: https://fedoraproject.org/wiki/Anaconda/Kickstart/KickstartingFedoraLiveInstallation

Bug 1108455 added preliminary support for image based provisioning of guest recipes to Beaker via the virt-image-install task (https://beaker-project.org/docs/user-guide/beaker-provided-tasks.html#distribution-virt-image-install), so this Anaconda feature may represent a way to bring a comparable capability to Beaker's bare metal provisioning support.