Adding Apache Behind Nginx

I saw this article by Karl Blessing (kbezzie.com) about letting Nginx do what it's good at, but passing back to Apache everything PHP, mod_rewrite, and htaccess, since that's something it's good at. I ran across this article when I was trying to configure Nginx to run a PHP interpreter and perform mod_rewrite-like tasks for a content management system, not WordPress. The concept makes sense to me.

1. Install both Nginx and Apache
2. Go to /etc/apache2/sites-available/000_default.conf and open in Nano.
3. Change default file to point to port 8000, or some other port than 80.
4. Go to /etc/nginx/sites-available/default and open in Nano.
5. Change the server block

server {
        listen 80 default_server;
        listen [::]:80 default_server ipv6only=on;

        root /var/www;
        index index.html index.php index.htm;

        # Make site accessible from http://localhost/
        server_name localhost;

        location / {
                try_files $uri $uri/ @backend;
        }

        location ~ \.php {
                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forward-For $remote_addr;
                proxy_set_header Host $host;
                proxy_pass http://127.0.0.1:8080;
        }

        location @backend {
                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forward-For $remote_addr;
                proxy_set_header Host $host;
                proxy_pass http://127.0.0.1:8080;
        }

   }

A Server Block defines a server_name and listen directives to bind to TCP sockets. In this case, the server_name is localhost. The listen directive is told to bind to port 80.

The root is the root of your web server. Both Nginx and Apache will share the web server root /var/www. This is important. I tried getting both Nginx and Apache to serve files from Nginx's default root, /usr/share/nginx/html, but that did not work. I'm not entirely sure it wasn't just a typo that made me fall back to /var/www, but when I did, the system started working. It may have been a permissions issue too.

The Location directive reads the requests coming from a browser, just the URI portion of the request--everything before the ?. The first one directs requests to use URI to find a file or a directory; otherwise, go to the proxy @backend. The location directive @backend, sends the requests via proxy_pass to localhost (127.0.0.1 port 8080), which is the Apache server. The location directive above @backend is case sensitive and uses a Regular Expression to filter the URI request string. Only those requests ending in .php are sent via proxy_pass to the Apache server.

proxy_set_header let's you to redefine or append the header that is passed to the proxy server. $remote_addr is $_SERVER['remote_addr'], a server variable containing the client address.

X-Forwarded-For is usually used by proxies to carry original Client IP through intermediary hops. I guess the same could be said for X-Real-IP. It's just used by proxies to carry original Client IP.

~ case-sensitive matching
~* case-insensitive matching