Proxy to upstream HTTPS server *with different* keys/certs in nginx

[tbamise]

Is it possible to use a different set of certs for the client side and
another set for the upstream server side?

My use case is to have different sets of local ssl certs on Nginx. A
key/cert pair for communicating with clients and another set for
communicating with the upstream proxy.

Right now I can define a server module with ssl and specify the ssl
certificates and specify a https protocol for proxy_pass for a location. But
both client and upstream connections end up using the same certificates
specified with $ssl_certificate. How can I specify different certificates
for the client side connection and upstream side connection?

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,247305,247305#msg-247305