Haskell-Scotty: Set custom headers (x-frame-options)

Question

Haskell newbie here!

In my haskell side project, I am using scotty to serve some dynamically generated html pages. The problem is that the pages can not be opened inside an iframe, due to the "x-frame-options" header set to "SAMEORIGIN".

How can I change that header to something different? I'd like to set that header for all responses. Is there a Middleware that can do that?

Thanks!

Answer 1

You can define your own middleware that adds this header to each response (all the tools neccesary are available in Network.Wai):

{-# LANGUAGE OverloadedStrings #-}

import Network.Wai -- from the wai package
import Web.Scotty hiding (options)

addFrameHeader :: Middleware
addFrameHeader =
  modifyResponse (mapResponseHeaders (("X-Frame-Options", "whatever") :))

Then use it in your scotty application:

main = scotty 6000 $ do
  middleware addFrameHeader
  get "/" (text "hello")

And with curl we can see that it is included in the response:

> curl --include localhost:6000
HTTP/1.1 200 OK
Transfer-Encoding: chunked
Date: Thu, 19 Jan 2017 19:22:57 GMT
Server: Warp/3.2.8
X-Frame-Options: whatever
Content-Type: text/plain; charset=utf-8

hello