🚧 wip: add placeholder for gauges

crates/ptth_server/src/file_server/metrics.rs

@@ -31,6 +31,11 @@ pub struct PerInstance {
 	pub startup_utc: DateTime <Utc>,
 }
 
+#[derive (Debug, serde::Serialize)]
+pub struct Gauges {
+	pub rss_mib: u64,
+}
+
 fn get_machine_id () -> Option <String> {
 	use std::{
 		fs::File,

crates/ptth_server/src/lib.rs

@@ -18,7 +18,10 @@ use handlebars::Handlebars;
 use reqwest::Client;
 use serde::Deserialize;
 use tokio::{
-	sync::oneshot,
+	sync::{
+		oneshot,
+		RwLock,
+	},
 	time::delay_for,
 };
 
@@ -52,6 +55,7 @@ struct ServerState {
 	config: Config,
 	handlebars: Handlebars <'static>,
 	instance_metrics: file_server::metrics::PerInstance,
+	gauges: RwLock <file_server::metrics::Gauges>,
 	client: Client,
 	hidden_path: Option <PathBuf>,
 }
@@ -210,6 +214,9 @@ pub async fn run_server (
 		},
 		handlebars,
 		instance_metrics,
+		gauges: RwLock::new (file_server::metrics::Gauges {
+			rss_mib: 7,
+		}),
 		client,
 		hidden_path,
 	});