Nginx – Any advantages of using nginx as a reverse proxy server in mainly php driven dynamic non-static webites

I don't think that there is a way to explicitly invalidate cached items, but here is an example of how to do the rest. Update: As mentioned by Piotr in another answer, there is a cache purge module that you can use. You can also force a refresh of a cached item using nginx's proxy_cache_bypass - see Cherian's answer for more information.

In this configuration, items that aren't cached will be retrieved from example.net and stored. The cached versions will be served up to future clients until they are no longer valid (60 minutes).

Your Cache-Control and Expires HTTP headers will be honored, so if you want to explicitly set an expiration date, you can do that by setting the correct headers in whatever you are proxying to.

There are lots of parameters that you can tune - see the nginx Proxy module documentation for more information about all of this including details on the meaning of the different settings/parameters: http://nginx.org/r/proxy_cache_path

http {
  proxy_cache_path  /var/www/cache levels=1:2 keys_zone=my-cache:8m max_size=1000m inactive=600m;
  proxy_temp_path /var/www/cache/tmp; 


  server {
    location / {
      proxy_pass http://example.net;
      proxy_cache my-cache;
      proxy_cache_valid  200 302  60m;
      proxy_cache_valid  404      1m;
    }
  }
}

Reverse proxying is slower and generally worse, however, some reasons to use it is to maintain (some) compatibility with .htaccess files (which you would have to write (and that isn't always practical) is you use a pure nginx setup) or if you require specific apache modules. (Some may argue that is you have these requirements, it is easier to just use apache.)

1. PHP-FPM with nginx would be the preferred solution - you get the fast static file serving of nginx and good PHP performance without adding additional overhead, proxying, or the (typically) significant memory usage of apache.
2. nginx+PHP-FPM is (typically) faster and uses less memory. Nginx + Apache + FastCGI/FPM will still serve static files fast, but will have additional overhead on the dynamic files (not as bad as mod_php, but worse than if you eliminate apache).
3. You will need a bit of both - nginx would need to know how to deal with the paths (e.g. for serving static files, denying access to .htaccess, etc) and apache will need to know how to handle the files. In some cases, if your .htaccess file doesn't pertain to static files (so every request that needs rewriting is going to go to apache), then it may be acceptable to simply deny access to certain locations, and have apache do the rest via .htaccess - it doesn't seem ideal, will cost a bit in performance, and its reliability is questionable - but it could work on a simple setup).

If you can, go with the straight nginx+PHP-FPM setup. If you can't, while there may be some merits to reverse-proxying, think through the repercussions, especially if you are dependent on .htaccess files.