Re: Legitimate exercise of our constitutional decision-making processes [Was, Re: Tentative summary of the amendments]

[Russ Allbery <rra@debian.org>]

The Wanderer <wanderer@fastmail.fm> writes:
> On 11/02/2014 at 07:58 PM, Russ Allbery wrote:

>> That's because the point of systemd-shim is to provide the services
>> that logind requires without running systemd as PID 1, so that packages
>> can then depend on logind without requiring systemd be PID 1.  That
>> didn't require a direct dependency on systemd because that dependency
>> comes in via libpam-systemd or some other route in the software using
>> logind.

>> In other words, the whole point of systemd-shim is to enable the use of
>> logind.  It's not replacing it with something else.

> ...I'm confused.

> Assuming you're correct in your description of the purpose of
> systemd-shim (I could argue that the concept of the package could /
> should extend to providing "stub" implementations of the interfaces
> provided by the various services provided by systemd-the-project), then
> it seems obvious that systemd-shim must necessarily depend on having
> systemd-the-package installed, since otherwise logind itself would not
> be installed.

> However, you've presented this as an explanation of the fact that
> systemd-shim does not list a "Depends: systemd" - when in fact it would
> seem to require that systemd-shim *must* list such a dependency.

Yeah, I was confusing, sorry.

The dependency direction is the other way around.  systemd-shim doesn't
depend on logind; logind depends on systemd-shim (in the absence of
systemd as PID 1).

So you're right that in theory you could use systemd-shim to enable the
use of other software that would otherwise want systemd as PID 1.
However, in practice what it's used for is allowing use of logind without
systemd.  Look at libpam-systemd, which is the key package for the
dependency structure since libpam-systemd being installed (and enabled)
effectively means logind is available.  libpam-systemd depends on systemd,
*and* on either systemd-sysv (systemd as PID 1) *or* on systemd-shim.

> This comes after I pointed out that the package does not list such a
> dependency, which comes after you (as far as I can tell) claimed that it
> had always listed such a dependency,

Well, what I said was that systemd-shim requires systemd, not that it
lists it as a dependency.  You're right that that's a confusing way of
putting it.

What I meant was that the normal use case of systemd-shim requires that
logind be installed, and hence also requires the systemd package.  In
other words, using systemd-shim for DEs doesn't avoid requiring logind.
It just provides another way of using logind.

The only point that I was trying to make is that systemd-shim is not
really an alternative to systemd.  It does provide a different
implementation of one feature (cgroups management) via cgmanager, but in
general you're still going to want systemd components installed, and
indeed the original goal of systemd-shim was to make that possible.

-- 
Russ Allbery (rra@debian.org)               <http://www.eyrie.org/~eagle/>