I have nginx configured to be my externally visible webserver which talks to a backend over HTTP.

The scenario I want to achieve is:

1. Client makes HTTPS request to nginx
2. nginx proxies request over HTTP to the backend
3. nginx receives response from backend over HTTP.
4. nginx passes this back to the client over HTTPS

My current config (where backend is configured correctly) is:

server {
        listen       80;
        server_name  localhost;

        location ~ .* {
            proxy_pass http://backend;
            proxy_redirect http://backend https://$host;
            proxy_set_header Host $host;
            }
        }

My problem is the response to the client (step 4) is sent over HTTP not HTTPS. Any ideas?