Starting Yesod without environment flag using mod_fastcgi

Question

To launch my Yesod application I need to provide an application environment argument for example:

./myYesodApp Production

Is there any way using Yesod to start the application and have the environment set as an environment variable or a configuration setting? So I can simply call:

./myYesodApp

I need to be able to do this so I can run my Yesod app using mod_fastcgi.

Alternatively is there any way to provide this argument to FastCgiWrapper?

My main.hs looks like this:

import Prelude              (IO, (>>=))
import Yesod.Default.Config (fromArgs)
import Yesod.Default.Main   (defaultMain)
import Settings             (parseExtra)
import Application          (makeApplication)
import Network.Wai.Handler.FastCGI (run)

main :: IO ()
main = fromArgs parseExtra >>= makeApplication >>= run

Answer 1

I think using withArgs :: [String] -> IO a -> IO a from System.Environment will be the easiest way to do this.

main = do
   env <- getEnv "YESOD_ENVIRONMENT"
   withArgs [env] (fromArgs parseExtra >>= makeApplication >>= run)