It is quite possible to run Nagios3’s web interface directly from Nginx and a FastCGI server, rather than having to involve a web application server like Apache. This is useful if you want to preserve memory on your machine, for example.
First of all, we ask Nginx to serve the static files for the Nagios web interface. In Debian/Ubuntu, these live in /usr/share/nagios3/htdocs and /usr/share/nagios3/stylesheets, which is a little awkward, but just the sort of thing that the rewrite command is for …