CloudFlare and F5 LTM X-Forwarded-For and X-Forwarded-Proto

If you want an application (such as Hippo) be able to determine what page is served with what protocol (http/https), you must insert an HTTP header when using a Apache ProxyPass.

When you use CloudFlare, the correct headers are inserted by default.

When you use an F5 loadbalancer, or in fact any loadbalancer or proxy, you must tell the loadbalancer to insert these two headers:

When you use a combination of the two, you have to make the loadbalancer a little smarter; it must detect if the header is present and add the header if not. That can be done by iRules.

The first iRule is to add "X-Forwarded-For" to the header:

when HTTP_REQUEST {
if {![HTTP::header exists X-Forwarded-For]}{
HTTP::header insert X-Forwarded-For [IP::remote_addr]
}
}

The second one is a bit more complex; it needs to verify if the X-Forwarded-Proto is available, and if not, add it, but based on it's original request to either port 80 (http) or port 443 (https):

when HTTP_REQUEST {
if {![HTTP::header exists X-Forwarded-Proto]}{
if {[TCP::local_port] equals 80}{
HTTP::header insert X-Forwarded-Proto "http"
} elseif {[TCP::local_port] equals 443}{
HTTP::header insert X-Forwarded-Proto "https"
}
}
}

Add these two iRules to your Virtual Service and with or without CloudFlare (or any other CDN) and your application can find the two headers to decide how to rewrite traffic.