Vlogger with a named pipe

In an old post I dealt with the nice mod_chroot module to secure your multisite server. I also adopted recently vlogger in order to manage better apache logs for virtual hosts, when you have dozens or hundreds of them. Unfortunately the suggested way to use it (a simple piped command) does not work nicely with mod_chroot, because the piped command has to run in the chroot jail.

Of course, it is not a good idea installing the whole perl intepreter and all required modules in a minimized jail, so I adopted an oldish classic trick (the old things are always the best) to solve the issue: using a named pipe. You basically need to do something like the following:

mkfifo -m 600 /var/run/apache2/logger && chown www-logs /var/run/apache2/logger

cat /var/run/apache2/logger | /usr/sbin/vlogger -u www-logs -g nogroup -s access.log /var/log/vlogger >/dev/null 2>&1 &

/etc/init.d/apache2 start

Of course your log directives will be something like:

LogFormat "%v %h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" vcombined
CustomLog "/var/run/apache2/logger" vcombined

You absolutely need to run the reader before the writer, else the init script would hang for ever. It is easy adding a simple init script to run vlogger before apache and it has also the big advantage of not requiring re-fork a perl intepreter at every damn log action. Piping rocks.