ngx_cache_purge not working with separate upstream php-fpm server

[kirkre]

I have the following issue with ngx_cache_purge. Any help with this will be greatly appreciated.

I'm using the Debian dynamically loaded ngx_cache_purge module in Bullseye. I have Nginx running in one server, and php-fpm running in a separate upstream server, with the goal of being able to horizontally scale php-fpm servers. The webroot is shared by both servers via nfs. With php-fpm running on a single server and all else being the same, purging through ngx_cache_purge works fine, using either curl or nginx-helper. With separate servers the cache fails to clear. Using nginx-helper there are no errors in the logs of nginx-helper, nginx, or php-fpm. Using curl there are no errors in the logs of nginx or php-fpm. The log level of php-fpm is debug, and the log level of nginx is warn. Here is the result I get trying to purge the cache with curl on the two server configuration:

curl -vvv -X PURGE -I http://localhost/bookings

• Trying 127.0.0.1:80...
• Connected to localhost (127.0.0.1) port 80 (#0)

PURGE /bookings HTTP/1.1
Host: localhost
User-Agent: curl/7.74.0
Accept: /

• Mark bundle as not supporting multiuse
  < HTTP/1.1 200 OK
  HTTP/1.1 200 OK
  < Server: nginx/1.18.0
  Server: nginx/1.18.0
  < Date: Sun, 04 Dec 2022 01:07:31 GMT
  Date: Sun, 04 Dec 2022 01:07:31 GMT
  < Content-Type: text/html; charset=UTF-8
  Content-Type: text/html; charset=UTF-8
  < Transfer-Encoding: chunked
  Transfer-Encoding: chunked
  < Connection: keep-alive
  Connection: keep-alive
  < Vary: Accept-Encoding
  Vary: Accept-Encoding
  < X-Powered-By: PHP/7.4.24
  X-Powered-By: PHP/7.4.24
  < Link: http://192.168.72.83/wp-json/; rel="https://api.w.org/"
  Link: http://192.168.72.83/wp-json/; rel="https://api.w.org/"
  < Link: http://192.168.72.83/wp-json/wp/v2/pages/540; rel="alternate"; type="application/json"
  Link: http://192.168.72.83/wp-json/wp/v2/pages/540; rel="alternate"; type="application/json"
  < Link: http://192.168.72.83/?p=540; rel=shortlink
  Link: http://192.168.72.83/?p=540; rel=shortlink

<

• Excess found: excess = 9944 url = /bookings (zero-length body)
• Connection #0 to host localhost left intact

Thanks,

Kirk