Reverse proxy with http inbound, https outbound, and parent proxy - nginx

Question

I have an application that needs to use a proxy (call it proxy1) to access some https endpoints outside of its network. The application doesn't support proxy settings, so I'd like to provide it a reverse proxy url, and I would prefer not to provide tls certs for proxy1, so I would use http for application -> proxy1.
I don't have access to the application host or forward proxy mentioned below, so I cannot configure networking there.
The endpoints the application needs are https, so proxy1 must make its outbound connections via https.
Finally, this whole setup is within a corporate network that requires a forward proxy (call it proxy2) for outbound internet, so my proxy1 needs to chain to proxy2 / use it as a parent.
I tried squid and it worked well for http only, but I couldn't get it to accept http inbound while using https outbound. Squid easily supported the parent proxy2.
I tried haproxy, but had the same result as with squid.
I tried nginx and it did what I wanted with http -> proxy -> https, but doesn't support a parent proxy. I considered setting up socat as in this answer, or using proxy_pass and proxy_set_header as in this answer, but I can't shake the feeling there's a cleaner way to achieve the requirements.
This doesn't seem like an outlandish setup, is it? Or is there a preferred approach for it? Ideally one using squid or nginx.

Answer 1

You can achive this without the complexity by using a port forwarder like socat. Just install it on a host to do the forwarding (or locally on the app server if you wish to) and create a listener that forwards connections through the proxy server. Then on your application host use a local name resolution overide to map the FQDN to the forwarder.
So, the final config should be the app server using a URI that points to the forwarding server (using its address if no name resolution excists), which has a socat listener that points to the the corporate proxy. No reverse proxy required.
socat TCP4-LISTEN:443,reuseaddr,fork \
PROXY:{proxy_address}:{endpoint_fqdn}:443,proxyport={proxy_port}
Just update with your parameters.