nginx. How to make friends 2 proxies?

Question

Nginx

Good day.
Tell me how to set up a bunch of two proxies?
There are a lot of web applications on the server, to which nginx proxied requests and locations in the form of #main
face
location / {
root /var/www/html;
try_files $uri $uri/ /index.html = 404;
}
#apps
location /app1 {
proxy_pass app1:8080
}
location /app2 {
proxy_pass app2:8080
}
And so on.
Now another proxy has been placed before this proxy, requests should now be sent to it and from it already be proxied to various sites and services. I made a config of a new virtual host for my project on the upstream proxy and requests to / forward just proxy_pass ip-address-second-proxy/, and I try to proxy requests to /app1, /app2 at 80 - the main one opens, if at 8080, then I get Access Denied
And I will not understand in any way how to transfer requests from the forward standing proxy to the standing one behind?

Answer 1

Separate locations on the new nginx are not needed, just proxy everything from it to port 80 of the old nginx, it will already figure it out by the url.