Bug#746578: libpam-systemd to flip dependencies - proposal
On Tue, 4 Nov 2014 17:54:53 +0000 Ian Jackson <ijackson@chiark.greenend.org.uk> wrote:
> I've been reading the messages from Josh about cgmanager etc., and
[snip]
Actually, I'd like to completely withdraw my concerns there, in light of
some new information.
Quoting Serge Hallyn, maintainer of cgmanager:
> Currently the cgmanager sytemd unit is installed inactive, so by default
> it will not interfere with systemd. The user needs to specifically
> enable it.
So, both systemd-shim and cgmanager seem entirely harmless on systemd
systems; the former will not run at all under systemd, and the latter
will not run by default under systemd. Based on that, I no longer have
any concerns about flipping the dependencies around, even though doing
so will likely pull those two packages in on systemd systems per
Christian Seiler's detailed analysis.
I don't see any obvious further steps that need to occur other than
flipping the dependency around. (It might be a good idea for the
libpam-systemd dependency to bump its versioned dependency on
systemd-shim to (>= 8-4), but that's up to the libpam-systemd
maintainers.)
(This is still orthogonal to any discussions regarding switching on
upgrades, or regarding dependencies on systemd.)
- Josh Triplett
> Rationale (Constitution 6.1(5)):
>
> 1. Currently libpam-systemd (which is pulled in by quite a few
> dependency chains) Depends on `systemd-sysv | systemd-shim (>= 8-2)'.
>
> 2. The effect of this is that installing some packages which depend
> (directly or indirectly) on libpam-systemd can cause a user's init
> system to be switched to systemd, even on systems where a user has
> deliberately chosen not to use the default init system, and even
> when the switch is unnecessary.
>
> 3. Swappping the order of these dependencies would avoid that and has
> no harmful effect:
>
> 4. In particular, on systems that already have systemd-sysv installed,
> libpam-systemd will still not pull in systemd-shim, thus minimizing
> the risk of breakage on systemd systems. However, on systems that
> intentionally do not have systemd installed, the installation of
> libpam-systemd will then prefer to pull in systemd-shim and keep
> the installed init system rather than switching to systemd-sysv.
>
> Decision (Constitution 6.1(4)):
>
> 5. We therefore overrule the decision of the maintainer of
> libpam-systemd binary package. The Depends entry
> systemd-sysv | systemd-shim (>= 8-2)
> should be replaced by
> systemd-shim (>= 8-2) | systemd-sysv
>
> 6. For the avoidance of doubt, we do not intend to set this specific
> syntax in stone. For example, if in future libpam-systemd needs to
> depend on a later systemd-shim, or needs a versioned rather than
> unversioned dependency on systemd-sysv, that is fine and would not
> contradict our decision.
>
> Release (Constitution 6.1(5)):
>
> 7. Our advice is that this change should be in jessie. If necessary,
> this view should be conveyed to the Release Team, after the change
> is in unstable, by filing an unblock request in the usual way.
>
> ===
>
>
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