console-conf uses 20+MB memory at rest on embedded systems

[Steve Langasek]

As reported in https://bugs.launchpad.net/ubuntu/+source/subiquity/+bug/1617232/comments/2, console-conf uses around 25MB of memory on an arm64 system, which is excessive for an idle process on an embedded device. And console-conf will be idle on a significant number of such systems, since some device manufacturers will not pre-configure an account and the vast majority of these devices will never have the end user log in on console to take ownership.

To avoid this gratuitous memory usage, I suggest we change the systemd unit to wrap the console-conf python program in a simple shell script prompting the user to hit enter.

Strawman implementation to get us started - wording to be confirmed on snapcraft list:

#!/bin/sh
set -e

echo -n 'Press enter to configure: '
read
exec console-conf "$@"

[Oliver Grawert (ogra)]

while the above will indeed help with the idling process,
it will still bump our minimal requirements by these 25MB since it needs this amount when actually running.

[Mark Shuttleworth (sabdfl)]

Good catch. Only question from me is whether (essentially) direct shell
access presents a security risk we may regret later. A minimalist "press
enter" app would be much easier to audit, and if written in something
more likely to be input-safe and yet still compiled would take very
little in the way of resources.

Is there already an "inetd" for consoles?

Mark

[Steve Langasek (vorlon)]

Turns out agetty actually already has options to pause before spawning its 'login' process. That's probably the way to go, using the -f option to specify a custom 'issue' file with the "Press enter" message.

[Mark Shuttleworth (sabdfl)]

Perfect outcome :)

[Michael Hudson-Doyle (mwhudson)]

Is the workaround considered sufficient for now? Can we close this?

[Oliver Grawert (ogra)]

i dont think using 20+ MB for such a tool is reasonable (1-2MB or even less would be...)
but given that the constant RAM occupation is gone for now at least ...