metrics/cfg: add a new entry for the Prometheus listen address

cmd/headscale/cli/utils.go

@@ -284,6 +284,7 @@ func getHeadscaleConfig() headscale.Config {
 	return headscale.Config{
 		ServerURL:         viper.GetString("server_url"),
 		Addr:              viper.GetString("listen_addr"),
+		MetricsAddr:       viper.GetString("metrics_listen_addr"),
 		GRPCAddr:          viper.GetString("grpc_listen_addr"),
 		GRPCAllowInsecure: viper.GetBool("grpc_allow_insecure"),
 

config-example.yaml

@@ -16,6 +16,12 @@ server_url: http://127.0.0.1:8080
 #
 listen_addr: 0.0.0.0:8080
 
+# Address to listen to /metrics, you may want
+# to keep this endpoint private to your internal
+# network
+#
+metrics_listen_addr: 127.0.0.1:8081
+
 # Address to listen for gRPC.
 # gRPC is used for controlling a headscale server
 # remotely with the CLI