bug#64775: /run should be cleaned on boot

[Csepp]

Vagrant Cascadian <vagrant@debian.org> writes:

> [[PGP Signed Part:Undecided]]
> So, if there are files sitting around in /run, they do not get cleaned
> up unless it is something guix is already aware of
> (e.g. /run/setuid-programs).
>
> I noticed this when experimenting with:
>
>   https://issues.guix.gnu.org/61462
>   Add support for file capabilities(7)
>
> Even after a reboot, the leftovers from that experimental patchset were
> still present in /run...
>
> While I know that Guix does not really follow the FHS in most respects,
> maybe the intention of /run defined there should still be respected?
>
>   https://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch03s15.html
>
>   3.15. /run : Run-time variable data
>   3.15.1. Purpose
>
>   This directory contains system information data describing the system
>   since it was booted. Files under this directory must be cleared
>   (removed or truncated as appropriate) at the beginning of the boot
>   process.
>   ...
>
> Many distros implement this by having /run on a tmpfs, but making sure
> to clean up /run at boot seems like a reasonable thing to do at the very
> least.
>
> I am not sure if it makes sense to do housecleaning of /run from guix
> system reconfigure ... as there may be legitimate uses for other
> processes to write there.
>
>
> live well,
>   vagrant
>
> [[End of PGP Signed Part]]

I vote for TMPFS, since that would also reduce flash wear.
Honestly I don't get why it's not already using TMPFS.