Fix middleware order for correct JSON marshaling

Query http handler is wrapped with so many middleware for different purposes. We want `serverutil.JSONMiddleware` to be wrapped on top of `serverutil.NewPrepopulatedMiddleware`, reason being, we `PrepopulatedMiddleware.next` to have proper `Content-Type` set with `application/json; charset=UTF-8`. without that, empty array response are convertion into `null` value in the HTTPResponse. Fixes: #4420 Signed-off-by: Kaviraj <[email protected]>
grafana · Oct 11, 2021 · 92e1f49 · 92e1f49
1 parent cdde2cf
commit 92e1f49
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Showing 2 changed files with 3 additions and 2 deletions.
diff --git a/pkg/loki/modules.go b/pkg/loki/modules.go
@@ -444,8 +444,8 @@ func (t *Loki) initQueryFrontend() (_ services.Service, err error) {
 		serverutil.RecoveryHTTPMiddleware,
 		t.HTTPAuthMiddleware,
 		queryrange.StatsHTTPMiddleware,
-		serverutil.NewPrepopulateMiddleware(),
 		serverutil.ResponseJSONMiddleware(),
+		serverutil.NewPrepopulateMiddleware(),
 	).Wrap(frontendHandler)
 
 	var defaultHandler http.Handler

diff --git a/pkg/querier/worker_service.go b/pkg/querier/worker_service.go
@@ -106,6 +106,7 @@ func InitWorkerService(
 	httpMiddleware := middleware.Merge(
 		serverutil.RecoveryHTTPMiddleware,
 		authMiddleware,
+		serverutil.ResponseJSONMiddleware(),
 		serverutil.NewPrepopulateMiddleware(),
 	)
 
@@ -124,8 +125,8 @@ func registerRoutesExternally(routes []string, externalRouter *mux.Router, inter
 	httpMiddleware := middleware.Merge(
 		serverutil.RecoveryHTTPMiddleware,
 		authMiddleware,
-		serverutil.NewPrepopulateMiddleware(),
 		serverutil.ResponseJSONMiddleware(),
+		serverutil.NewPrepopulateMiddleware(),
 	)
 
 	for _, route := range routes {