Nginx / WordPress — Proxy Subdirectory to WordPress Subdomain

Using Nginx to proxy a subdirectory to a wordpress installation on a subdomain.

I’m moving our blog onto our main site, but want to keep them on separate servers from the main site for various reasons.

The blog will be on blog.anuvawines.com, but be accessible from anuvawines.com/blog (for SEO, since google thinks of subdomains as separate sites).

Double Update: Don’t do it!

It’s more trouble than its worth for me — I simply bought a bigger server to handle a separate PHP process and let nginx actually serve it at /blog/.

Update: I ran into issues with permalinks due to the proxy. It looks like WP checks the ‘home’ option against something to pull the post_ID from your permalink format. I tried digging in and replacing option_get(‘home’) where i thought the ID was being generated, but couldn’t solve the issue.

My end solution was to set the home field to the real address where WP is hosted, and to edit the link generator itself to pull data from a new option field I made called proxy_home.

That way, all my issues were solved.

For my peace of mind, I made my subdomain return a 403 forbidden if a certain header was not passed to the subdomain on proxy.  Of course, this could be any other method that generally IDs the proxy server (ip/referrer/whatever). The reason is not for security, so anything goes.

Set up the nginx proxy

Say we want to proxy domain.com/blog/ to blog.domain.com. Note that I say proxy, because we don’t want a redirect. We want a 200 http status message. One that google will crawl as apart of domain.com/

Set up a location in your /etc/nginx/nginx.conf aside your other location directives.

location /blog/ {
 proxy_pass http://static.anuvawines.com/wordpress ;
 proxy_set_header X-Real-IP $remote_addr;
 proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}

Restart nginx, and you’re good to go. Visit the mydomain.com/blog and you will be able to navigate to the site, with an HTTP 200 message.

The only problem is that the links are still using the subdomain address, and if you tried admin authentication, it fails.

Set up wordpress links to use proxy address

This is pretty much good to go out of the box, but you will have to change your WordPress installation to rewrite the urls for your proxy domain instead.

Right now, all links are subdomain.mydomain.com/, when they should be accessed by domain.com/blog

add a few lines to your wp-config.php

define('WP_HOME', 'http://mydomain.com/blog');
define('WP-SITEURL', 'http://mydomain.com/blog');

Reload the page and your urls should be set to the new ones.

Fixing admin/authentication for proxy address

Suddenly, we have a problem. We can’t log in via the proxy, OR the actual subdomain address because we set the above 2 lines.

subdomain.mydomain.com/login will redirect to mydomain.com/blog and fail.

I dug around the cookie headers to see that wordpress is looking for a database entry called home and siteurl to set these cookies. The above code fixed our links, but these cookies look directly at the db. I suspect this means the above step is useless.

So, go into your mysql db, alter the wp_options table, option_name “siteurl” and option_name “home”, and set them to the proxy address.

In my case, anuvawines.com/blog

The cookies will now match the domain when you are logging in via the proxy address.