EAR passwords not being saved after Docker container restarts

[Buckie]

So this might pertain to later versions of the Server, but since I haven't tested it on newer ones, I'll just let this question sit here.

I have created the image according to these official instructions and everything is mostly working fine except for EAR passwords not being saved upon reboots. Within a single session those are saved, fmsadmin stop and start server preserve them, but reboot your container - they're gone. It's the same as taking a drive with a FileMaker Server install and plugging it into another machine. Those passwords seem to be dependent on some kind of hardware ID that Docker re-generates upon every boot, so those keys don't validate afterwards.

Does anyone know what identifiers or values must be preserved within Docker so that the Server knows it's the same machine booting up and not something "new"?