I've been using Nginx for a few years now and plan to do so for many more, but it wasn't an easy setup to get used to. In fact, I'm still getting bit by the differences between it and Apache, which I have much more experience with. The one difference that stands out the most of the
For the most part, Apache directives are matched in a top down manner with later directives overwriting earlier ones if duplicated. Nginx directives on the other hand seem to operate a little differently.
According to the official documentation , this is how nginx processes a request:
nginx first searches for the most specific prefix location given by literal strings regardless of the listed order. In the configuration above the only prefix location is "/" and since it matches any request it will be used as a last resort. Then nginx checks locations given by regular expression in the order listed in the configuration file. The first matching expression stops the search and nginx will use this location. If no regular expression matches a request, then nginx uses the most specific prefix location found earlier.
The same thing, said a little differently according to Samuel at the RackCorp Industry Blog :
The best way to think of things is that as a request comes in, Nginx will scan through the configuration to find a "location" line that matches the request. There are TWO modes that nginx uses to scan through the configuration file: literal string matching and regular expression checks. Nginx first scans through ALL literal string location entries in the order that they occur in the configuration file, and secondly scans through ALL the regular expression location entries in the order that they occur in the configuration file. So be aware – location ordering order DOES matter.
- Linode Library, Basic Nginx Configuration, Location Configuration
- nginx wiki - HttpCoreModule (Official)
- nginx module documentation, nginx core http (Official)
- stackoverflow - location directive matching order
- History of nginx
- Securing nginx and PHP