Bug#945269: debian-policy: packages should use tmpfiles.d(5) to create directories below /var

[Simon McVittie <smcv@debian.org>]

On Sat, 30 Nov 2019 at 10:58:23 -0800, Russ Allbery wrote:
> Guillem Jover <guillem@debian.org> writes:
> > I don't mind much how this could end up being hooked into various init
> > systems and chroot/container managers. I can see how it could be done by
> > the respective imeplementations themselves or provided by dpkg itself,
> > I'm open to any of these TBH.
> 
> One possibly interesting option would be for dpkg to take responsibility
> for writing the tmpfiles.d configuration file for a package based on its
> own metadata

I think the other way round could also make sense: having dpkg create
variable/transient directories, and track them as owned by the package,
using its tmpfiles.d fragment(s) as input (either directly, or via a
debhelper step that takes tmpfiles.d as input and registers it with dpkg
as output).

That way, in the hopefully-common case where the upstream developer
of a system service installs a tmpfiles.d fragment for the files that
their package owns (most likely generated at build-time with appropriate
Autoconf/etc. @substitutions@), the packaged version will do the right
thing, without the packager having to take action specifically.

Prior art/naming: I think RPM "ghost files" are files tracked as owned
but not actually shipped in the RPM?

    smcv