> This issue reached its pinnacle for us when we were unable to figure out how to replicate the magic response composition syntax used by Spray to abstract away

> This issue reached its pinnacle for us when we were unable to figure out how to replicate the magic response composition syntax used by Spray to abstract away the addition of CORS headers to HTTP responses. I'd just put any kind of application, whether built in Scala, node.js or Go or ruby on rails behind a nginx proxy and use that for setting the headers. That simplifies a lot of things. I hope your HTTP headers aren't really so dynamic that you need to build software that changes them so much, especially not for a RESTful application.