Use sql to generate jwt, rather than custom haskell

src/PostgREST/Middleware.hs

@@ -19,6 +19,7 @@ import           PostgREST.ApiRequest          (ApiRequest(..), ContentType(..),
 import           PostgREST.Auth                (claimsToSQL, JWTAttempt(..))
 import           PostgREST.Config              (AppConfig (..), corsPolicy)
 import           PostgREST.Error               (errResponse)
+import           PostgREST.QueryBuilder        (pgFmtLit)
 
 import           Protolude                     hiding (concat, null)
 
@@ -45,6 +46,10 @@ runWithClaims conf eClaims app req =
       ]
       (toS $ "{\"message\":\""<>message<>"\"}")
 
+exposeSecretToSQL :: Maybe Text -> H.Transaction ()
+exposeSecretToSQL mS = do
+  for_ mS $ \s ->
+    H.sql $ "set local postgrest.jwt_secret = " <> toS (pgFmtLit s) <> ";"
 
 defaultMiddle :: Application -> Application
 defaultMiddle =