[v11.0.x] Loki: Support custom X-Query-Tags header (#86189)

Loki: Support custom `X-Query-Tags` header (#85123)

* Loki: Support custom `X-Query-Tags` header

* add comment

(cherry picked from commit 9a8ae3c932)

Co-authored-by: Sven Grossmann <sven.grossmann@grafana.com>

pkg/tsdb/loki/parse_query.go

@@ -100,23 +100,26 @@ func parseDirection(jsonPointerValue *string) (Direction, error) {
 	}
 }
 
-func parseSupportingQueryType(jsonPointerValue *string) (SupportingQueryType, error) {
+func parseSupportingQueryType(jsonPointerValue *string) SupportingQueryType {
 	if jsonPointerValue == nil {
-		return SupportingQueryNone, nil
-	} else {
-		jsonValue := *jsonPointerValue
-		switch jsonValue {
-		case "logsVolume":
-			return SupportingQueryLogsVolume, nil
-		case "logsSample":
-			return SupportingQueryLogsSample, nil
-		case "dataSample":
-			return SupportingQueryDataSample, nil
-		case "infiniteScroll":
-			return SupportingQueryInfiniteScroll, nil
-		default:
-			return SupportingQueryNone, fmt.Errorf("invalid supportingQueryType: %s", jsonValue)
-		}
+		return SupportingQueryNone
+	}
+
+	jsonValue := *jsonPointerValue
+	switch jsonValue {
+	case "logsVolume":
+		return SupportingQueryLogsVolume
+	case "logsSample":
+		return SupportingQueryLogsSample
+	case "dataSample":
+		return SupportingQueryDataSample
+	case "infiniteScroll":
+		return SupportingQueryInfiniteScroll
+	case "":
+		return SupportingQueryNone
+	default:
+		// `SupportingQueryType` is just a `string` in the schema, so we can just parse this as a string
+		return SupportingQueryType(jsonValue)
 	}
 }
 
@@ -166,10 +169,7 @@ func parseQuery(queryContext *backend.QueryDataRequest) ([]*lokiQuery, error) {
 			legendFormat = *model.LegendFormat
 		}
 
-		supportingQueryType, err := parseSupportingQueryType(model.SupportingQueryType)
-		if err != nil {
-			return nil, err
-		}
+		supportingQueryType := parseSupportingQueryType(model.SupportingQueryType)
 
 		qs = append(qs, &lokiQuery{
 			Expr:                expr,