Comment 1 for bug 1989995

I am seeing this behavior on a raspberry pi. I am using docker which now requires several modules from ...modules-extra, but having a problem where the oob behavior is the system works fine until at some point modules disappear and the docker daemon can't boot on reboot.
Extensively searching the internet you can find this issue showing up a lot where extra kernel modules get installed.
I have traced the problem I am having back to the copymods package which it seems results in a tmpfs holding all modules.
It doesn't seem like apt always knows this.. Or at least there are some states where apt installs additional modules which somehow don't make it to the tmpfs modules folder on reboot.