Load Secret File

Main.hs

loadSecretFile :: AppConfig -> IO AppConfig
loadSecretFile conf = extractAndTransform mSecret
  where
      mSecret   = configJwtSecretOrFile   conf
      isB64     = configJwtSecretIsBase64 conf

      extractAndTransform :: Maybe Text -> IO AppConfig
      extractAndTransform Nothing  = return conf
      extractAndTransform (Just s) =
        case stripPrefix "@" s of
          Nothing       -> setSecret <$> transformString isB64 s
          Just filename -> fmap setSecret $ transformString isB64 =<< readFile (toS filename)

      transformString :: Bool -> Text -> IO ByteString
      transformString False t = return . encodeUtf8 $ t
      transformString True  t =
        case decode (encodeUtf8 t) of
          Left errMsg -> panic $ pack errMsg
          Right bs    -> return bs

      setSecret bs = conf { configJwtSecret = Just bs }