How to make nginx caching proxy return last-modified from backend?

Question

Nginx

It is necessary to force the caching proxy on nginx to give the last-modified header from the backend (the backend provides it). The location configuration is as follows:

location /file.js {
    proxy_pass http://some-domain.com;
    sub_filter "subject" "replacement";
    sub_filter_types "text/javascript";
    sub_filter_once off;
    proxy_set_header Accept-Encoding "";
    proxy_pass_header Server;
}

Answer 1

sub_filter_last_modified on;