How to make take variable from hostname and substitute it as proxy port?

Question

Nginx

Greetings! The bottom line is that there are several boxed builds on gitlab, for each deployment goes to its own host.
For example box100.example.net, box101.example.net ..... box109.example.net Hosts
are described as regular expression box10[0-9]{1}\.example\.net
on lnmp.
I need to somehow extract a number from the hostname, make it a variable $box_port and substitute it in proxy_pass.
for example proxy_pass http://10.15.31.11:${box_port}80;

Answer 1

I got it like this:

server_name "~^box(?<box_port>[\d]{3})\example\.ru$" ;
proxy_pass http://$proxy_app:${box_port}80;

Answer 2

sed? expressions for extracting part of a string are highly dependent on the input data - what is correct for one case often needs to be rewritten for another
, it usually looks like
(this is just an example)
x=$(blah | sed -n "s/.*\(${SELENIUM_VERSION}\ /selenium-server-standalone[^<][^>]*\)<\/Key>.*/\1/p")