CORS header ‘Access-Control-Allow-Origin’ missing in servant

Question

using the run from Network.Wai.Handler.Warp function to server rest api

run :: Port -> Application -> IO ()

but while doing post request, getting an error CORS header ‘Access-Control-Allow-Origin’. any idea how to overcome this in servant/haskell

Answer 1

You could use wai-cors middleware to add CORS headers.

At the end you'll have something like

app = simpleCors $ serve api serverImpl

where

• simpleCors is a Middleware from wai-cors
• serve turns servant handlers into wai Application
• api :: Proxy YourAPI
• serverImpl is your handlers' implementation