Should libpam-elogind Provide libpam-systemd ?

[Ian Jackson <ijackson@chiark.greenend.org.uk>]

Hi.

tl/dr: would this be wrong
   Package: libpam-elogind
   Provides: libpam-systemd
and should there be a Conflicts too ?

(emailing the systemd maintainers since that's Providing their package
 name, and also d-devel since I'm not sure what input others may have)


There's an active effort now to fix some of the problems that are
evident with sysvinit in buster.[1]  We are tackling the services
provided to (primarily) desktop sessions by systemd-logind, and
specifically pam_systemd.so which AIUI is part of the machinery for
arranging that console users get permission to do various things.

In stretch this was handled on many sysvinit systems by systemd-shim.
That is not really maintained - the version in sid right now is broken
- and its approach means that it keeps breaking and is awkward to fix.

In buster it looks like we are going to try to do this by using
elogind.  elogind is not in sid yet but we already have a half-working
prototype.

elogind provides a pam module to replace pam_systemd.so.  We are
considering having libpam-elogind.deb Provide libpam-systemd.

Is there some reason that would be a bad idea ?  Should it also
Conflict libpam-systemd ?

The alternative to this Provides would seem to be an MBF requesting
updates of all the dependencies.  (Maybe some other virtual package is
needed.)

(Our draft package ships libpam_elogind.so, but there are some
difficulties with pam configuration ending up referring to both
libpam_elogind.so and libpam_systemd.so and generating warnings, and a
few packages seem to explicitly refer to pam_systemd.so, for instance
lightdm's /etc/pam.d/lightdm-greeter.  If we can't resolve that we may
need to ship the pam module as libpam_systemd.so and that might
involve Replaces as well as Conflicts.)

We would be grateful to receive technical advice and opinions - and
corrections to any wrong assumptions.  To save my colleagues on d-i-d
having to come to debian-devel I will summarise the responses.

Thanks,
Ian.

[1] If you would like to come and help with improving Debian's
support for alternatives to systemd, please join this mailman list
  http://www.chiark.greenend.org.uk/mailman/listinfo/debian-init-diversity

We are particularly in need of more `desktoppy' expertise.

-- 
Ian Jackson <ijackson@chiark.greenend.org.uk>   These opinions are my own.

If I emailed you from an address @fyvzl.net or @evade.org.uk, that is
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