Cargohold: Log more about AWS errors (#1205)

We will probably make it less verbose again in the future, but at the
moment this is helpful for debugging issues caused by switching to
amazonka.

* cargohold: log more AWS errors

* add comments to amazonka log level mapping

Copied from other services. Might be nice to unify this?

services/cargohold/src/CargoHold/AWS.hs

@@ -129,8 +129,17 @@ mkEnv lgr s3End s3Download bucket cfOpts mgr = do
         <&> AWS.configure s3
     awsLogger g l = Logger.log g (mapLevel l) . Log.msg . toLazyByteString
     mapLevel AWS.Info = Logger.Info
+    -- Debug output from amazonka can be very useful for tracing requests
+    -- but is very verbose (and multiline which we don't handle well)
+    -- distracting from our own debug logs, so we map amazonka's 'Debug'
+    -- level to our 'Trace' level.
     mapLevel AWS.Debug = Logger.Trace
     mapLevel AWS.Trace = Logger.Trace
+    -- n.b. Errors are either returned or thrown. In both cases they will
+    -- already be logged if left unhandled. We don't want errors to be
+    -- logged inside amazonka already, before we even had a chance to handle
+    -- them, which results in distracting noise. For debugging purposes,
+    -- they are still revealed on debug level.
     mapLevel AWS.Error = Logger.Debug
 
 execute :: MonadIO m => Env -> Amazon a -> m a
@@ -158,13 +167,23 @@ throwA :: Either AWS.Error a -> Amazon a
 throwA = either (throwM . GeneralError) return
 
 exec ::
-  (AWSRequest r, MonadIO m) =>
+  (AWSRequest r, Show r, MonadLogger m, MonadIO m, MonadThrow m) =>
   Env ->
   (Text -> r) ->
   m (Rs r)
 exec env request = do
-  let bucket = _s3Bucket env
-  execute env (AWS.send $ request bucket)
+  let req = request (_s3Bucket env)
+  resp <- execute env (sendCatch req)
+  case resp of
+    Left err -> do
+      Log.info $
+        Log.field "remote" (Log.val "S3")
+          ~~ Log.msg (show err)
+          ~~ Log.msg (show req)
+      -- We just re-throw the error, but logging it here also gives us the request
+      -- that caused it.
+      throwM (GeneralError err)
+    Right r -> return r
 
 execCatch ::
   (AWSRequest r, Show r, MonadLogger m, MonadIO m) =>
@@ -176,7 +195,7 @@ execCatch env request = do
   resp <- execute env (retrying retry5x (const canRetry) (const (sendCatch req)))
   case resp of
     Left err -> do
-      Log.debug $
+      Log.info $
         Log.field "remote" (Log.val "S3")
           ~~ Log.msg (show err)
           ~~ Log.msg (show req)

services/cargohold/src/CargoHold/S3.hs

@@ -107,7 +107,7 @@ uploadV3 ::
   Conduit.ConduitM () ByteString (ResourceT IO) () ->
   ExceptT Error App ()
 uploadV3 prc (s3Key . mkKey -> key) (V3.AssetHeaders ct cl md5) tok src = do
-  Log.debug $
+  Log.info $
     "remote" .= val "S3"
       ~~ "asset.owner" .= toByteString prc
       ~~ "asset.key" .= key
@@ -728,7 +728,7 @@ parseAmzMeta k h = lookupCI k h >>= fromByteString . encodeUtf8
 octets :: MIME.Type
 octets = MIME.Type (MIME.Application "octet-stream") []
 
-exec :: (AWSRequest r) => (Text -> r) -> ExceptT Error App (Rs r)
+exec :: (AWSRequest r, Show r) => (Text -> r) -> ExceptT Error App (Rs r)
 exec req = do
   env <- view aws
   AWS.exec env req