Re: dispatcher conditions

[Yclept Nemo <orbisvicis gmail com>]

Resending this message, forgot to cc the networkmanager mailing-list.
Stupid gmail (or me). In any case, is this thread worth filing an RFE
on bugzilla ?

On Tue, Mar 2, 2010 at 2:25 AM, Dan Williams <dcbw redhat com> wrote:
> On Sun, 2010-02-28 at 16:45 -0500, Yclept Nemo wrote:
>> Quick question, can the dispatcher scripts in
>> "/etc/NetworkManager/dispatcher.d/*" be run when:
>>  down) only when no more public interfaces remain
>>  up) only when the first public interface is brought up
>
> Not entirely; 'man NetworkManager' has more details, but you will get
> up/down events when *any* NM managed interface is taken up or down, not
> just when there's a connection or not.  If you get a "down" event, there
> may well be another interface that still has a connection.
>
> We could explore the possibility of adding two more events indicating
> when there is any connection, and when there is no longer any
> connection.

I think it would be fruitful to explore adding such events. Example scenario:
Networked daemons such as ntpd need only be brought up with the first
accessible "user" or "system" network connection (see below) and
should only be terminated along with the last accessible connection.
Currently bringing down any extraneous connections also stops such
daemons. For example, a tenuous wireless connection on a laptop also
possessing a wired network would have ntpd unnecessarily flickering on
and off in tandem with the wireless connection.

>> I say "public" because iirc via consolekit some network connections
>> can be exclusive to starting user? ...doesn't really matter though.
>> I'm only dealing with the root user.
>
> There are "system" connections and "user" connections.  Since you're
> only dealing with root, all your connections should probably be "system"
> connections.  System connections are stored either by distro-specific
> plugins, or by the distro-agnostic 'keyfile' plugin to
> NetworkManager/nm-system-settings.
> See /etc/NetworkManager/nm-system-settings.conf for more information, or
> take a look at:
>
> http://live.gnome.org/NetworkManager/SystemSettings
>

Thanks for the documentation and terminology. All my connections are
"user" initiated by nm-applet - one wired and one wireless, and though
I could convert the wired connection to a "system" connection there is
no need. It seems that processes running as root (for example, ntpd)
have no problem accessing "user" connections. According to
[http://live.gnome.org/NetworkManagerConfiguration] "User connections
are *only* available to the specified user" ... and root ?

--

On the other hand not all daemons run as root and might only be able
to access "system" connections. Then different daemons would need to
be stopped or started at different times.
All these events might be a bit silly:
[all connections down]
[first connection up]
[all system connections down]
[first system connection up]
For example the apache2 worker processes run under the "webserver"
user and I think manage/access the network connections while the root
apache2 process only handles user switching and startup/shutdown.

It's a bad example but this is out of my league. Unlike apache, ntpd
needs to be started with access to a time server in order to
immediately set the clock. Honestly this dispatcher script would work,
but it seems crude:
up) /etc/rc.d/openntpd restart # long (unnecessary) time changes after
boot-up can adversely affect other daemons
down) "explicit_do_nothing_function" # possibly let ntpd timeout
*) echo "not cool"

so...

thanks,