Hello,
I want to see $token to $tk not "$tk" and I think nginx doesn't understand two variables. But I can be not right, actually.
I have to cut out some part from uri and use that in sub-request. Is there some workaround for that?

my conf for that https://pastebin.com/u0ddzD3H and it doesn't work

I've solved this with

location ~ '^/el/(?<tk>.+)/(?<tail>php/\d/[\w+/\.-=_]+)?$' {
set $auth_request_uri "http://127.0.0.1:10101/auth/$tk";
auth_request /auth;
autoindex on;
alias /var/ftp/pub/centos/php/$tail;

}

location /auth {
internal;
proxy_pass $auth_request_uri;
proxy_pass_request_body off;
proxy_set_header Content-Length "";
proxy_set_header X-Original-URI $request_uri;
}