Nginx not captures regex variables

Question

Trying to capture URLs like http://mydomain/1234567890123 (13 digits)

 location ~ ^/([\d]{13})$ { proxy_pass http://127.0.0.1:4000/product?id=$1; } 

$1 variable arriving empty, even if URL is being captured. What am I missing?

P.S. Tried also named variables. Not helps.

Answer 1

An extract from a working configuration using a map:

map $uri $maptest { "~^(?<folder1>.*?)/?(\?.*)?$" page-cache$folder1/1.html; } server { location /node_direct/ { proxy_pass http://nodeServers/$maptest; } }