Here’s a use case: You want to run an application server that only speaks HTTP, but securely, over HTTPS. The problem is that the application server won’t know that it’s being accessed via HTTPS, so any URLs and redirects it generates might point to HTTP. Here’s an example virtual host entry that takes care of that by rewriting the header.
You need Apache, mod_proxy and mod_headers.
<VirtualHost *:443> ServerName foo.bar.example.com SSLEngine on SSLCertificateFile /etc/ssl/certs/ssl-cert-snakeoil.pem SSLCertificateKeyFile /etc/ssl/private/ssl-cert-snakeoil.key Header edit Location "^http:(.*)$" "https:$1" PassengerEnabled off ProxyPass / http://127.0.0.1:3000/ ProxyPassReverse / http://127.0.0.1:3000/ DocumentRoot /var/www/foo/bar <Directory /var/www/foo/bar> AllowOverride none Options -MultiViews </Directory> </VirtualHost>
The magical line is the one with “Header edit…”. This makes sure any request your app server would have sent to HTTP are rewritten to HTTPS.