https://docs.ubuntu.com/static/maas-1.9/orientation_architecture-diagram.png
Debugging ephemeral image
Troubleshooting | MAAS | MAAS documentation
https://docs.ubuntu.com/maas/2.1/en/troubleshoot-faq#debugging-ephemeral-image
MaaS images at
/var/lib/maas/boot-resources/*/*/*/*/*/*/root-image