Allow root path as metrics path. (#2590)

Signed-off-by: LamGC <lam827@lamgc.net>

node_exporter.go

@@ -186,6 +186,7 @@ func main() {
 	level.Debug(logger).Log("msg", "Go MAXPROCS", "procs", runtime.GOMAXPROCS(0))
 
 	http.Handle(*metricsPath, newHandler(!*disableExporterMetrics, *maxRequests, logger))
+	if *metricsPath != "/" {
 		landingConfig := web.LandingConfig{
 			Name:        "Node Exporter",
 			Description: "Prometheus Node Exporter",
@@ -203,6 +204,7 @@ func main() {
 			os.Exit(1)
 		}
 		http.Handle("/", landingPage)
+	}
 
 	server := &http.Server{}
 	if err := web.ListenAndServe(server, toolkitFlags, logger); err != nil {