feat(metrics): Record metrics with OpenTelemetry and export over OTLP

src/api/client/membership/invite.rs

@@ -2,6 +2,7 @@ use axum::extract::State;
 use conduwuit::{
 	Err, Result, debug_error, err, info,
 	matrix::{event::gen_event_id_canonical_json, pdu::PartialPdu},
+	metrics::KeyValue,
 	trace, warn,
 };
 use futures::FutureExt;
@@ -113,6 +114,31 @@ pub(crate) async fn invite_helper(
 	room_id: &RoomId,
 	reason: Option<String>,
 	is_direct: bool,
+) -> Result {
+	let result =
+		send_invite(services, sender_user, recipient_user, room_id, reason, is_direct).await;
+
+	let destination = if services.globals.user_is_local(recipient_user) {
+		"local"
+	} else {
+		"remote"
+	};
+	services.server.metrics.instruments.invites.add(1, &[
+		KeyValue::new("direction", "outgoing"),
+		KeyValue::new("destination", destination),
+		KeyValue::new("outcome", if result.is_ok() { "success" } else { "failure" }),
+	]);
+
+	result
+}
+
+async fn send_invite(
+	services: &Services,
+	sender_user: &UserId,
+	recipient_user: &UserId,
+	room_id: &RoomId,
+	reason: Option<String>,
+	is_direct: bool,
 ) -> Result {
 	if !services.users.is_admin(sender_user).await && services.config.block_non_admin_invites {
 		info!(

src/api/client/unversioned.rs

@@ -2,6 +2,7 @@ use axum::{Json, extract::State, response::IntoResponse};
 use conduwuit::{
 	Err, Result,
 	matrix::versions::{unstable_features, versions},
+	metrics::PROMETHEUS_CONTENT_TYPE,
 	utils::string::constant_time_eq,
 };
 use futures::StreamExt;
@@ -80,7 +81,7 @@ pub(crate) async fn continuwuity_local_user_count(
 
 /// # `GET /_continuwuity/metrics`
 ///
-/// Prometheus metrics in the OpenMetrics text format. Only routed when
+/// Prometheus metrics in the text exposition format. Only routed when
 /// `allow_prometheus_metrics` is enabled.
 pub(crate) async fn continuwuity_metrics(
 	State(services): State<crate::State>,
@@ -100,14 +101,7 @@ pub(crate) async fn continuwuity_metrics(
 		}
 	}
 
-	services.update_metrics()?;
-	let body = services.server.metrics.prometheus.encode()?;
+	let body = services.server.metrics.render()?;
 
-	Ok((
-		[(
-			header::CONTENT_TYPE,
-			"application/openmetrics-text; version=1.0.0; charset=utf-8",
-		)],
-		body,
-	))
+	Ok(([(header::CONTENT_TYPE, PROMETHEUS_CONTENT_TYPE)], body))
 }