by Terence Collins
and Philip Greenspun
part of ArsDigita Free Tools
ArsDigita Watchdog is a system that monitors your AOLserver's error
log at regular, short intervals, and notifies the necessary
individuals via email. In keeping with ArsDigita's
server architecture philosophy
, if you are maintaining multiple
services, or just one service that sees a lot of traffic, you want to
save yourself the trouble of opening up the log file(s) in emacs and
then poring over the logs to discover errors strewn amidst various
notices and errors you'd rather ignore. ArsDigita Watchdog allows you
- Specify multiple maintainers to notify of errors occuring in your log.
- Specify individuals to notify of errors only occuring in certain subdirectories.
- Specify patterns of errors of which you'd rather not be notified.
Watchdog is built using AOLserver
(free) and takes advantage
of AOLserver's built-in scheduler (like Unix cron but lighter weight)
and Tcl API. However, unlike most of our AOLserver products, you
don't need to install an RDBMS in order to use Watchdog. Web servers
generally get stuck because of problems with the RDBMS, so a monitor
that depended on an RDBMS would be self-defeating.
Watchdog is written to match the format and peculiarities of the
AOLserver error log, however the source is freely available and can be
hacked to handle other servers' error logs.
- Download watchdog.tar.gz (last updated
April 30, 1999)
tar xvf watchdog.tar.gz (creates /web/watchdog.dist)
mv watchdog.dist watchdog
- Create an AOLserver whose page root is /web/watchdog and whose
private Tcl directory is /web/watchdog/tcl. Alternatively, you
could install watchdog as a subdirectory in another web server, so
long as you symlink the watchdog .tcl files from your server's tcl
- Edit /tcl/defs.tcl to set the main Watchdog parameters.
- Make sure your watchdog directory is writable by nsadmin.
- You're done! Start your server
- April 30, 1999: fixed bug wherein watchdog would stop running if an error file could not be found
This is open-source software, copyright 1998 ArsDigita, LLC and licensed
under the GNU General
Support and Customization
If you want a extended version of Watchdog or support, you can hire
the programmer of your choice to install, maintain, and customize Watchdog.
offers support as well, but
probably not at a price that you'd be happy to pay.