Dan has moved on from Moodle sadly. The setup we originally setup for CLEO before it was taken by BT/LCC was not dockerised. I don't think that Docker existed when we built that platform.
It was first setup in about 2006, and we ran the sites on bare metal. If memory serves, when we handed over to BT, it was running a set of five high-thread frontends, a pair of MySQLi DB servers running multi-master, and a Hot-spare NFS backend.
The service was providing Moodle 1.9 (Moodle 2.0 had only recently come out when the transfer process began).
When we handed it over it was still bare metal, with no virtualisation.
Out of interest, what kind of changes did you end up making to it?