Nginx cache for Wordpress

upstream backend{
    # Defines backends.
    # Extracting here makes it easier to load balance
    # in the future. Needs to be specific IP as Plesk
    # doesn't have Apache listening on localhost.
    ip_hash;
    server 127.0.0.1:8080; # IP goes here.
}

server {
    listen 80 default_server; # IP goes here.
    server_name _;

    # Max upload size: make sure this matches the php.ini in .htaccess
    client_max_body_size 20m;
	  access_log   /var/log/nginx/cache_access.log rt_cache;

    # Catch the wordpress cookies.
    # Must be set to blank first for when they don't exist.
    set $user_auth "";

    if ($http_cookie ~* "wordpress_logged_in_[^=]*=([^%]+)%7C") {
        set $user_auth user_auth_$1;
    }

    if ($http_cookie ~* "ci_session_app") {
        set $user_auth user_auth_$1;
    }

    # Set the proxy cache key
    set $cache_key $scheme$host$uri$is_args$args;

    # Don't cache these pages.
    location ~* ^/(wp-admin|wp-login.php){
        more_clear_headers "X-Powered-By";
        proxy_pass http://backend;
    }

    location ~* ^/(ec){
        proxy_pass http://backend;
	      more_set_headers "Server: Elav Hosting";
        more_clear_headers "X-Powered-By";
    }


    location / {
        proxy_pass http://backend;
        proxy_cache main;
        proxy_cache_key $cache_key;
        proxy_cache_valid 5m; # 200, 301 and 302 will be cached.
        # Fallback to stale cache on certain errors.
        # 503 is deliberately missing, if we're down for maintenance
        # we want the page to display.
        proxy_cache_use_stale error
                              timeout
                              invalid_header
                              http_500
                              http_502
                              http_504
                              http_404;
        # 2 rules to dedicate the no caching rule for logged in users.
        proxy_cache_bypass $user_auth; # Do not cache the response.
        proxy_no_cache $user_auth; # Do not serve response from cache.
        proxy_set_header X-Forwarded-For $remote_addr;
    	dd_header X-Cache $upstream_cache_status;
    	 more_set_headers "Server:Host Cache";
        more_clear_headers "X-Powered-By";
    }

}