Wordpress Reverse Proxy Plugin

reverse-proxy.php

<?php
/**
 * @package Reverse Proxy
 */
/*
Plugin Name: Reverse Proxy
Plugin URI: https://instrumentalapp.com/
Description: Reverse proxy setup for Instrumental blog
Version: 1.0
Author: James Paden
Author URI: https://instrumentalapp.com
*/


// Change to match the desired subfolder, no leading or tralling slash
// if there is no subfolder because using subdomains leave blank
define("RP_SUBFOLDER", "");

function rp_is_login_page() {
    return in_array($GLOBALS['pagenow'], array('wp-login.php', 'wp-register.php'));
}

if ( $_SERVER["REMOTE_ADDR"] != "127.0.0.1" && !is_admin() && !rp_is_login_page() && $_GET["preview"] != "true" ) {
    add_action( 'init', function () {
    	if (!$_SERVER["HTTP_X_IS_REVERSE_PROXY"]) {
    		//not coming from us, 404 it.
    		header($_SERVER["SERVER_PROTOCOL"]." 404 Not Found");
    		exit;
    	}
    });

    //From http://stackoverflow.com/questions/772510/wordpress-filter-to-modify-final-html-output
    ob_start();
    add_action('shutdown', function() {
        $final = '';
        //$levels = count(ob_get_level());
            //`$levels = ob_get_level();`the count() function is not needed and actually causes the buffer to fail. For more info, see link in comments to SO thread.
        $levels = (ob_get_level());
        for ( $i = 0; $i < $levels; $i++ ) {
            $final .= ob_get_clean();
        }

        // Apply any filters to the final output
        //$final = str_replace("http://" . $_SERVER["HTTP_HOST"], "https://" . $_SERVER["HTTP_X_ORIGINAL_HOST"] . "/" . RP_SUBFOLDER, $final);
        //site has ssl and removed the "/" 
        $final = str_replace("https://" . $_SERVER["HTTP_HOST"], "https://" . $_SERVER["HTTP_X_ORIGINAL_HOST"] . RP_SUBFOLDER, $final);

        echo $final;
    }, 0);
}

z-httpd-vhosts.conf

# Example code for Apache Proxy config
# Put this inside the <VirtualHost> directive
# replace subfolder with "/" to allow for full subdomain to be proxied
# RequestHeader set Host was key to proxying to the correct site within the WP multisite
<Location />
    RequestHeader set X-Is-Reverse-Proxy true
    RequestHeader set X-Original-Host yourfinalwebsite.com
    ProxyPass http://yourwordpresssitesubdomain.com
    ProxyPassReverse http://yourwordpresssitesubdomain.com
    RequestHeader set Host yourwordpresssitesubdomain.com
</Location>

z-nginx-config.txt

# Example code for Nginx config
# Put this inside the "server {" section
# check nginx info (Google) to match Apache config to nginx proxy config
location /blog/ {
  proxy_set_header X-Original-Host $host;
  proxy_set_header X-Is-Reverse-Proxy "true";
  proxy_pass_header Set-Cookie;
  proxy_cookie_path / /blog/;
  proxy_pass http://yourwordpresssitesubdomain.com/;
}