Dynamic proxy_pass based on location - nginx

Question

I'm trying to create dynamic proxy_pass based on location (to be run in docker and redirect traffic to docker stacks hosting http, based on stack name)
Here's my current config. Ive got to the point of working redirect with static location (commented variants at the bottom with blue/green redirect properly and application is working fine). I got problem with dynamic location (~^/(?<ver>.*)/(?<rest>.*)?$) - there's issue with proper glueing of the target URL. When i go to https://myapp.com/blue/, nginx logs issue with dns resolution blue could not be resolved (3: Host not found), looks like it cuts everything after $<ver> in http://${ver}_${subdomain}/$rest. Im not an REGEX expert and i probably messed the location part, any suggestions?
server {
listen 80;
server_name ~^(?<subdomain>.+)\.(mydomain\.com|mydomain\.pl)$;
resolver 127.0.0.11 ipv6=off;
location ~^/(?<ver>.*)/(?<rest>.*)?$ {
set $target http://${ver}_${subdomain}/$rest;
proxy_pass $target;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
# location ~ ^/blue/((?<rest>.*))?$ {
# set $exdomain http://blue_$subdomain/$rest;
# proxy_pass $exdomain;
# proxy_set_header Host $host;
# proxy_set_header X-Real-IP $remote_addr;
# proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
# }
# location ~ ^/green/((?<rest>.*))?$ {
# set $exdomain http://green_$subdomain/$rest;
# proxy_pass $exdomain;
# proxy_set_header Host $host;
# proxy_set_header X-Real-IP $remote_addr;
# proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
# }
proxy_connect_timeout 90;
proxy_send_timeout 90;
proxy_read_timeout 90;
send_timeout 90;
}

Answer 1

* in a regular expression is greedy, so $ver will capture everything until the last /, and not the next / as you intended.
One solution is to use the non-greedy variant *? (not to be confused with ?), for example:
location ~ ^/(?<ver>.*?)/(?<rest>.*)?$ { ... }
But a better solution is to use a character class that excludes /, for example:
location ~ ^/(?<ver>[^/]+)/(?<rest>.*)?$ { ... }
See this useful resource on regular expressions.