[rsyslog] desktop notifications from syslog

[Michael Biebl]

2009/4/29 Tom Metro <tmetro+rsyslog at gmail.com>:
> Is there a recommended technique for displaying notifications on a GUI
> desktop from syslog? To me it seems like a significant oversight that
> such a feature isn't built-in to modern desktop distributions of Linux.
> Below the covers the machine could be in serious distress, and the
> casual GUI user would be oblivious to it. (I'm aware of xconsole, but
> it's more for viewing logs, not getting notifications of just the
> serious problems.)
>
> In an attempt to implement such a feature using a small bit of
> scripting, the notify-send command (uses libnotify for GUI
> notifications), and named pipes fed by sysklogd, I ran into reliability
> problems. It seemed like sysklogd sometimes closed the pipe and never
> reopened it again until it was restarted.
>
> That led me to rsyslog, which supports the convenient command-execute
> target. So a rule like:
>
> *.crit                          ^/usr/local/bin/rsyslog-notify
>
> executing a script like:
>
> #!/bin/bash
> XOWNER=<user>
> DISPLAY=:0.0 XAUTHORITY=/home/$XOWNER/.Xauthority notify-send
> --urgency=critical --expire-time=0 "SYSLOG: $1" 2>>
> /var/log/rsyslog-notify.log
>
>
> does the trick. (It needs a bit of code added to automatically figure
> out the owner of the display. For now, <user> is statically replaced
> with the correct user.) However, it took a little bit longer than
> necessary to determine that the DISPLAY and XAUTHORITY variables were
> necessary, because rsyslog ignores the STDERR produced by the executed
> command. It'd be nice if that output was logged, or otherwise brought to
> the admin's attention.
>
> I'm wondering if notify-send should be ran in the background to avoid it
> potentially hanging rsyslog, as warned in the documentation. I don't
> think doing so would have any negative impact on the operation.
>
> An rsyslog output module that directly used the libnotify API might be a
> nice thing to have, too.
>

Why not a dbus output plugin, and a small client app, that runs in the
users desktop session, subscribes to the dbus messages and displays
them via libnotify.

Cheers,
Michael


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