From a8bff4525642a4e25be8dca6f83b3eb00c6cec0d Mon Sep 17 00:00:00 2001
From: Galen Kistler <109082771+gtk-grafana@users.noreply.github.com>
Date: Fri, 26 Sep 2025 07:18:20 -0500
Subject: [PATCH] Loki: resource frontend browser cache (#110488)

feat: allow frontend to set browser cache for config endpoint
---
 pkg/tsdb/loki/loki.go | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/pkg/tsdb/loki/loki.go b/pkg/tsdb/loki/loki.go
index 4b68c66b42a..5626ca94ee5 100644
--- a/pkg/tsdb/loki/loki.go
+++ b/pkg/tsdb/loki/loki.go
@@ -162,6 +162,13 @@ func callResource(ctx context.Context, req *backend.CallResourceRequest, sender
 	respHeaders := map[string][]string{
 		"content-type": {"application/json"},
 	}
+
+	// frontend sets the X-Grafana-Cache with the desired response cache control value
+	if len(req.GetHTTPHeaders().Get("X-Grafana-Cache")) > 0 {
+		respHeaders["X-Grafana-Cache"] = []string{"y"}
+		respHeaders["Cache-Control"] = []string{req.GetHTTPHeaders().Get("X-Grafana-Cache")}
+	}
+
 	if rawLokiResponse.Encoding != "" {
 		respHeaders["content-encoding"] = []string{rawLokiResponse.Encoding}
 	}