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Open Source Technologies

Notes ServerName domain3.com
ErrorLog /home/sites/domain3/logs/error.log
CustomLog /home/sites/domain3/logs/web.log
</VirtualHost>

In the above example, we have three domains with three unique Web logs (using the combined
format we defined earlier). A traffic analysis package could then be scheduled to process these
logs and generate reports for each domain independently.

This method works well for most hosts. However, there may be situations where this could
become unmanageable. Apache recommends a special single log file for large virtual host
environments and provides a tool for generating individual logs per individual domain.
We will call this log type the cvh format, standing for “common virtual host.” Simply by adding
a %v (which stands for virtual host) to the beginning of the combined log format defined
earlier and giving it a new nickname of cvh, we can compile all domains into one log file, then
automatically split them into individual log files for processing by a traffic analysis package.

LogFormat “%v %h %l %u %t “%r” %>s %b “%{Referer}i” “%{User-Agent}i”” cvh

In this case, we do not make any CustomLog entries in the <VirtualHost> containers and simply
have one log file generated by Apache. A program created by Apache called split_logfile is
included in the src/support directory of your Apache sources. from your master log file will
be named for each domain (virtual host) and look like: virtualhost.log.
4.3.4 Log Rotation

Finally, we want to address log rotation. High traffic sites will generate very large log files,
which will quickly swallow up valuable disk space on your server. You can use log rotation to
manage this process. There are many ways to handle log rotation, and various third party tools
are available as well. However, we’re focusing on configurations native to Apache, so we will
look at a simple log rotation scheme here. I’ll include links to more flexible and sophisticated
log rotation options in a moment.
This example uses a rudimentary shell script to move the current Web log to an archive log,
compresses the old file and keeps an archive for as long as 12 months, then restarts Apache
with a pause to allow the log files to be switched out.
mv web11.tgz web12.tgz

mv web10.tgz web11.tgz

mv web9.tgz web10.tgz
mv web8.tgz web9.tgz
mv web7.tgz web8.tgz

mv web6.tgz web7.tgz

mv web5.tgz web6.tgz
mv web5.tgz web6.tgz
mv web4.tgz web5.tgz

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