[systemd-devel] feature request: dlopen

[Luke Kenneth Casson Leighton]

i don't know if you've seen this yet:
http://news.slashdot.org/story/15/02/15/1959209/removing-libsystemd0-from-a-live-running-debian-system

my name's luke leighton, i'm a software libre advocate, and the first
major contribution that i made to software libre was to help bridge
the impossible chasm between the microsoft world and the unix world,
back in 1996 to 1999, by implementing and documenting NT Domains as
well as a proper Network Neighbourhood (features of which,
interestingly, have since been completely reimplemented in the form of
avahi and zeroconf).

i now tend to keep to myself except in circumstances where i perceive
something similar occurring in the software libre community: a
polarisation or an opportunity to extend (or reduce) the reach of
software libre.  a decision that has been made which makes the lives
of huge numbers of ordinary users and systems administrators
incredibly difficult, forcing them to make impossible decisions - that
sort of thing.

 i note that there was announcement recently that the systemd team
'listens to users', so i am taking you at your word on that.

now, i'm keenly aware of the views (technical and more) of systemd:
i'm aware that there have been polls.  most of them remind me of
mother theresa's refusal to go to a "war protest" rally - she pointed
out that next time they had a *peace* rally, to give her a call.

so i'm not going to "protest" - i'm going to try a different approach.
i'd like you to look at this list of debian packages that are
dependent on libsystemd0:
http://lkcl.net/reports/removing_systemd_from_debian/list_of_libsystemd0_dependent_packages.txt

it's an enormous list, comprising some 15% of the packages present in
debian today.  it includes apache2-dev, bluetooth / bluez, the gimp,
php, *all* of the video players (xine, mplayer, vlc), *all* of the
games and 3D packages that use SDL or pulseaudio (which is most of
them), *all* of the major desktop environments including xfce4, lxde,
Gnome and KDE/Plasma, cups-daemon, one of the anti-virus daemons, most
of the music software packages and services, most of the VoIP clients,
the android SDK, the eclipse IDE, OpenJDK 7, erlang, Apache
Tomcat..... i'm just absolutely blown away by the extent of the
dependencies.

oh - and php as well.  what the heck php5 is doing with a hard
dependency on libsystemd0 i cannot imagine.

now, because those are hard compile-time dependencies, the only
possibility for the average debian user who chooses *not* to have
libsystemd0 present on their system is for them to simply... not use
*anything* on that list of over four and a half THOUSAND packages.

i think the most important question to ask you at this point is: as a
team, were you aware of the extent to which libsystemd0 has become a
hard compile-time dependency on so many critical software packages in
use today?

and the second question, which is just as important, is: does this
shock or alarm you enough to appreciate why people find the rapid
introduction of libsystemd0 to be so objectionable?  before answering,
please bear in mind that i have done an analysis of a similar library
and runtime (which i worked with a decade ago and am a minor
contributor on): libselinux1 and SE/LInux.

i can tell you right now that the way in which SE/Linux was introduced
is *genuinely* completely different from the one that has brought us
libsystemd0 (and has nothing to do with the technical debate, merits
or otherwise of the software *or* its alternatives).

 in fact, the way in which libselinux1 was introduced - the careful
research, the definition of its scope, how its instigators stuck to a
clear roadmap, and its gradual introduction as an *optional* component
that could be tested, deployed and rolled back *without* inconvenience
or attempting to reverse impossiblly challenging or irreversible
decisions if found to be troublesome, could be said (with
understatement) to be a humbling model that libsystemd0 should learn
from, retrospectively, very very fast.

now, since beginning to write this a couple of days ago, i have
encountered this:
* https://lists.debian.org/debian-devel/2015/02/msg00189.html
* http://forums.debian.net/viewtopic.php?f=20&t=119836

there, we see that a debian developer has created unofficial packages
that, if installed, provide replacements for key strategic packages
entirely recompiled *without* systemd and without libsystemd0 being
present.

the key here is that they *are* entirely unofficial, making the
decision to install them a difficult one, and flat-out impossible for
many deployments where there are rules and contracts in place that
prevent and prohibit the use even of debian-backports, let alone
unofficial repositories.

also, adam's work is only going to get harder and harder as time goes
by, as the depth and extent of systemd's reach increases.  so, whilst
it's a good thing that adam has achieved what he has, it can
definitely be said to be a "stop-gap measure" - allowing a *small
subset* of users and administrators some interim relief whilst this is
properly resolved.

moving on: in what adam wrote (rather hot-headedly, initially), he
goes on to mention that it would be perfectly reasonable to replicate
the effects of how he removed libsystemd0, in a way that would be far
less disruptive to end-users and sysadmins, and far less divisive:
dynamic library loading.

the technique's nothing new: it's extremely common and as experienced
software libre developers i'm sure you've even written code in the
past or maintain some now that uses dlopen to great effect.

as i am partly writing to a public audience who may not be so
knowledgeable, please excuse me for describing that the advantages,
are, as you know, that a pre-compiled package may, at runtime, detect
what is available to it and use it. it may even be configured via a
config option to disable the use of that functionality at runtime even
if the dynamic library is present.  you know this.

so can i leave it with you to consider whether the current situation
is tolerable or not?  that situation is unfortunately one of closing
your doors to the voices that are telling you (mostly incoherently, so
its hardly surprising that you choose to ignore them!) that there
really *is* a problem here that is *not* going to go away, no matter
how much you might wish it to, and no matter how much you may be
*saying* that you listen to users.  in other words: whilst the voices
may be incoherent or even abusive, it's only when they stop will you
know that you did something right :)

i am one of the few people who can cut through all that, who has gone
to the trouble of digging into why libsystemd0 is found to be so
objectionable.  my take on the matter is that the technical arguments
- benefits or otherwise - of systemd and its alternatives - is
completely irrelevant.  over time people *will* develop alternatives
(and are already doing so: mdev, eudev, uselessd, openrc and many
more).

no, i feel that it really does have nothing to do with the technical
benefits of the available options: what people are finding completely
objectionable is that they have *no good choices*.  it's "use systemd
or go away" - and unfortunately almost without exception (slackware
and FreeBSD being two notable ones) that "piss off" attitude is being
replicated across *the entire GNU/Linux Distro world*.  the situation
is completely unprecedented and without parallel in the short history
of software libre (and that's something that, honestly, i find to be
really shocking, hence why i am contacting you).

overall, they feel that they're being forced into the use of something
that they feel has not been properly thought through, is still under
development, is increasing in scope in a way that alarms them due to
there being no other choices, causes them some huge inconvenience that
they'd rather have a bit more time to consider but they are *not being
given that chance*, and much more.

this is a rapidly untenable escalating situation that is having an
adverse detrimental effect that i feel is *your* responsibility to
defuse.... and quickly.  and you may do so through the simple process
of converting a couple of userspace applications within your control
over to use the well-known dynamic-library-loading technique.

i have to tell you: i even heard, on slashdot, that microsoft is now
using - to significant success - the situation surrounding systemd as
a sales pitch to have GNU/linux systems successfully replaced with
windows servers.  that GNU/linux is being relegated to the hypervisor
/ management role of windows systems which are successfully claimed to
be much more dependable.  systemd is being used to successfully
*scare* people into buying windows - back into the arms of the
monopoly power i worked incredibly hard to give people a way to move
away from.  i have to say: I'm Officially Not Happy With You (tm) for
that :)

i hope... my hope is that, by providing you with these insights and a
potential and easily-deployed solution (in going through all the
packages and hard-removing libsystemd0, adam was in a unique position
to evaluate the dlopen option and found it to be technically easy to
do), i hope that i have shocked you into taking immediate action.  my
hope here is that you will realise the gravity and enormity of the
situation that the software libre world faces right now, sufficient
that you will give this absolute top priority above everything else
that cannot be immediately put on hold.

i am subscribed to this list on "nomail", and will follow it on gmane.
as you are experienced software developers i would not presume to
interfere with how to go about dynamically-loading of libsystemd0,
however if you would appreciate the benefit of my experience (which
comes in part from one of the software libre world's more experienced
unix portability experts, andrew tridgell), i will be more than happy
to help as i can.

l.