Redirect non-http requests to https in a general fashion (no need to hardcode hostnames).
The incoming path and params will be included in the redirect. For example, http://example.com/thing?id=2 will redirect to https://example.com/thing?id=2.
Concat your crt, key (password removed), and any other crts in the chain.
Avoid relative paths unless you're certain of haproxy's working directory.
This header will help most web frameworks (express, rails, sinatra) when they generate absolute urls. The generated urls will include the right protocol (i.e. https).
The upside is that you can avoid conditional code in your application for handling https. Your application really shouldn't be doing that anyway.
This is the default port socket.io uses for the flash policy.
Read more at The Carbon Emitter.