Respond with 502 on every backend exception

From RFC 7231:

6.6.3.  502 Bad Gateway

   The 502 (Bad Gateway) status code indicates that the server, while
   acting as a gateway or proxy, received an invalid response from an
   inbound server it accessed while attempting to fulfill the request.

1 files changed, 6 insertions, 2 deletions

diff --git a/src/Sproxy/Application.hs b/src/Sproxy/Application.hs
index 5de9474..3d6598f 100644
--- a/src/Sproxy/Application.hs
+++ b/src/Sproxy/Application.hs
@@ -30,8 +30,8 @@ import Network.HTTP.Conduit (requestBodySourceChunkedIO, requestBodySourceIO)
 import Network.HTTP.Types (RequestHeaders, ResponseHeaders, methodGet, methodPost)
 import Network.HTTP.Types.Header ( hConnection,
   hContentLength, hContentType, hCookie, hLocation, hTransferEncoding )
-import Network.HTTP.Types.Status ( Status(..), badRequest400, forbidden403, found302,
-  internalServerError500, methodNotAllowed405, movedPermanently301,
+import Network.HTTP.Types.Status ( Status(..), badGateway502, badRequest400, forbidden403,
+  found302, internalServerError500, methodNotAllowed405, movedPermanently301,
   networkAuthenticationRequired511, notFound404, ok200, seeOther303, temporaryRedirect307 )
 import Network.Socket (NameInfoFlag(NI_NUMERICHOST), getNameInfo)
 import Network.Wai.Conduit (sourceRequestBody, responseSource)
@@ -383,12 +383,16 @@ notFound msg req resp = do
 logException :: W.Middleware
 logException app req resp =
   catches (app req resp) [
+    Handler badGateway,
     Handler internalError
   ]
   where
     internalError :: SomeException -> IO W.ResponseReceived
     internalError = response internalServerError500
 
+    badGateway :: BE.HttpException -> IO W.ResponseReceived
+    badGateway = response badGateway502
+
     response :: Exception e => Status -> e -> IO W.ResponseReceived
     response st e = do
       Log.error $ show (statusCode st) ++ " " ++ unpack (statusMessage st)