Re: Network Manager does not find system wide connections

[Dan Williams <dcbw redhat com>]

On Sun, 2009-08-09 at 00:51 +0100, Graham Lyon wrote:
> 
> 
> 2009/8/9 Hadmut Danisch <hadmut danisch de>
>         Graham Lyon wrote:
>         >
>         >
>         > Then documentation should be fixed, not the method itself.
>         DBus is the
>         > best approach to do this, it uniffies IPC in unix, which is
>         a *good*
>         > thing.
>         
>         
>         Network configuration is such an essential and basic function,
>         that it
>         should not depend
>         on IPC.  IPC means that  several processes must exist, and
>         this is error
>         prone by default.
>         
>         IPC may be an addon, but it should work without IPC.
>         
> 
> I can see what you're saying here and I sympathise. Perhaps the best
> solution would be one where there is a single NM daemon on the system
> level that manages the interfaces and deal with the system config and
> then supplies a (probably the same) DBus API that allows user
> processes to manage user-configured connections. A merger of
> NetworkManager and nm-system-settings, basicly. This removes the need
> for IPC in order to get the core of it working whilst at the same time
> still supplying the same funcionality. The more that I think about it
> the more I agree with you on this point that NetworkManager shouldn't
> be useless without DBus and the nm-settings-daemon running also.

NM master (0.8) already has merged NM + nm-system-settings; there is
only one core NetworkManager process now.  However, to control NM, you
still need D-Bus.  It is completely pointless to re-implement IPC via a
socket just so you don't depend on D-Bus.  So then you've got both (a) a
standard, well-understood, type-safe D-Bus interface, and (b) a
non-standard, hacked up duplicated socket-based control interface.
Fail.  There is nothing wrong with D-Bus, period.  Or maybe people will
finally accept D-Bus when it's a kernel module (as Marcel Holtmann has
proposed)?

Something Hadmut didn't consider was that maybe the distros *should*
start D-Bus in single-user mode.  That's what I mean by change; the
distros aren't stuck in stone in how they are configured and what
software they run by default.

>         > NM is not interweaved with desktop applications. You're
>         confusing the
>         > user settings manager with network manager itself.
>         
>         
>         A plain user will store his network settings under Gnome or
>         KDE and such
>         within the Gnome and KDE
>         configuration methods. This depends on desktop applications.
>         Without a
>         desktop network manager will
>         not find any user specific config. 
> 
> I'm not entirely sure what you meant here, but I suspect you mean that
> an ordinary user will configure their system using the applets in
> gnome/kde and so their settings will not be system settings? They only
> need to tick the "make available to all users" ticky box. If I
> completely misread what you're saying, please do correct me.
> 
> 
>         And I did not yet see any command line front end.
>         
> 
> There is cnetworkmanager, apparently (I've never used it) and there
> was discussions on this list somewhere about a rewrite of it to make
> it more functional.

Probably not a rewrite, but another tool in C more suitable to
size-constrained installs, or people who just don't want to depend on
Python.  There is certainly room for both and neither would obsolete the
other.  Martin does good work.

>         > It's actually the best way to get the two levels of
>         configuration that
>         > I can think of.
>         
>         Storing network configuration in Gnome or KDE in a way that
>         they are not
>         available if someone uses the other Desktop is a bad idea.
>         Network
>         settings are
>         not desktop settings and thus should not be stored in the
>         Gnome or KDE
>         configuration.
>         
> 
> Fair point, but how often do you switch to using the other desktop
> environment as the same user login? It's not a particularly common use
> case... I will admit that the network settings are not part of your
> desktop settings and the problem here is that there is no unified
> settings daemon for all user's applications (something like this is
> really lacking in the world of linux and would be great as it would
> stop everyone having to roll their own config file reading/writing
> mechanism.

If you want to use user connections in a different DE, you can make them
system connections and they will be available to any DE that you use.
That's actually the whole point of system connections; it doesn't matter
what user or GUI you're using, they are still there.
 
> 
>         > It doesn't need a running desktop to be configured, and lots
>         of system
>         > relevent applications require DBus (it's not a desktop
>         program).
>         
>         
>         And that's wrong.
>         
>         DBus is not started in single user mode. So NetworkManager
>         could not be
>         used in single user mode.
>         
>         A network configuration that does not work in single user mode
>         is a flaw.
> 
> See above. I'm not particularly familiar with single user mode (I've
> never had the need to use it, rather thankfully) but is it possible
> that dbus could be added to the things that are started in single user
> mode?

Right; there is no reason that NetworkManager cannot be used in
single-user mode.  Plenty of services get started in single-user mode,
and NetworkManager + dbus can be two of those if people need networking
there.  Alternatively, you can always have your way with ifconfig and
iwconfig and wpa_supplicant manually.  But if you don't want to screw
around with all that, just start NM.

In the end, I'm not sure there's much we can say to Hadmut; we're pretty
off the original topic of pre-down.

Dan
 
> 
>         >     Networking must be able to work even in single user mode
>         in a simple
>         >     terminal
>         >     with a shell session and must not depend on anything
>         else.
>         >
>         >
>         > Correct me if I'm wrong, but I think it does as long as the
>         daemon is
>         > started and the system settings daemon is started.
>         
>         
>         That's one of the problems. Network configuration must not
>         depend on
>         that many daemons.
>         
>         Network configuration must be able to work on its own, even if
>         everything else is absent.
> 
> I proposed a possible solution to this a little further up in this
> mail. I'm not sure how the devs will feel about it but it actually
> makes more sense from a design point of view to me. Though I don't
> pretend to know about the network manager internals so it could be
> impossible...
> 
> Graham
>