refactor datasource check of loki

center/router/router_datasource.go

@@ -137,14 +137,15 @@ func DatasourceCheck(ds models.Datasource) error {
 	if ds.PluginType == models.PROMETHEUS {
 		subPath := "/api/v1/query"
 		query := url.Values{}
-		if strings.Contains(fullURL, "loki") {
-			subPath = "/api/v1/labels"
-		} else {
-			query.Add("query", "1+1")
-		}
+		// if strings.Contains(fullURL, "loki") {
+		// 	subPath = "/api/v1/labels"
+		// } else {
+		// 	query.Add("query", "1+1")
+		// }
+		query.Add("query", "mock_metric_name")
 		fullURL = fmt.Sprintf("%s%s?%s", ds.HTTPJson.Url, subPath, query.Encode())
 
-		req, err = http.NewRequest("POST", fullURL, nil)
+		req, err = http.NewRequest("GET", fullURL, nil)
 		if err != nil {
 			logger.Errorf("Error creating request: %v", err)
 			return fmt.Errorf("request url:%s failed", fullURL)