Nginx caching proxy dns name even when using variables

[Rob Fulton]

Hi,

I'm using nginx to proxy to a host with a rapidly changing dns entry but 
I can't seem to get the proxy command the re-query dns using the 
vairable method suggested, the following is a excerpt from my config :

server {

     listen 443 ssl;

     resolver 127.0.0.1 valid=20s;
     set $proxy_server somehostname.com;

     location / {

         proxy_pass https://$proxy_server/blue/content$request_uri;


I'm using nginx 1.14, watching my dns logs I see no requests following 
nginx starting up. The upstream_addr value in my nginx logs also doesn't 
change.

Any suggestions of why this isn't working as expected?

Regards

Rob