Nginx Plugin Error Message; will it work on non commercial Nginx


I have my own VM instance running Nginx 1.9+ mainline on Centos 7 / Php 5.6 with Fastcgi. Have several different clients running instances of WP. Not running easy engine. Was able to get Fast CGI running and caching correctly. However, needed a solution to purge and came across Nginx Helper. Several questions:

  1. Is it best practice to create a single Fastcgi instance serverwide, or better to create an instance per WP site. Wondering this because if a WP user purges cache from their site dashboard, will it clear only their site cache or caches for ALL sites.

  2. Does Nginx helper need “fastcgi_cache purge module” to work correctly? According to Nginx, it’s only available in the Commercial Version with a hefty price tag? Will the plugin work for the open source version (which I have)?

  3. I installed Nginx helper on a test site, and I an error when I click the Purge site link: “path not defined”. The path to my cache is “/dev/shm/nginx” (I did this because I thought I read where this is the RAMdisk location.

I’ve inserted " define(‘RT_WP_NGINX_HELPER_CACHE_PATH’,’/dev/shm/nginx/’); " into wp-config and restarted both php and nginx with no change. How would I get this to work?

Thanks for your help!