feat: [#1403] add extendable-labeled metrics to http-tracker-core and expose in REST API

**URL:** http://0.0.0.0:1212/api/v1/metrics?token=MyAccessToken

**Sample response:**

```json
{
  "metrics":[
    {
      "kind":"counter",
      "name":"http_tracker_core_announce_requests_received_total",
      "samples":[
        {
          "value":1,
          "update_at":"2025-04-02T00:00:00+00:00",
          "labels":[
            {
              "name":"server_binding_ip",
              "value":"0.0.0.0"
            },
            {
              "name":"server_binding_port",
              "value":"7070"
            },
            {
              "name":"server_binding_protocol",
              "value":"http"
            }
          ]
        }
      ]
    },
    {
      "kind":"gauge",
      "name":"udp_tracker_server_performance_avg_announce_processing_time_ns",
      "samples":[
        {
          "value":1.0,
          "update_at":"2025-04-02T00:00:00+00:00",
          "labels":[
            {
              "name":"server_binding_ip",
              "value":"0.0.0.0"
            },
            {
              "name":"server_binding_port",
              "value":"7070"
            },
            {
              "name":"server_binding_protocol",
              "value":"http"
            }
          ]
        }
      ]
    }
  ]
}
```

**URL:** http://0.0.0.0:1212/api/v1/stats?token=MyAccessToken&format=prometheus

```
http_tracker_core_announce_requests_received_total{server_binding_ip="0.0.0.0",server_binding_port="7070",server_binding_protocol="http"} 1
udp_tracker_server_performance_avg_announce_processing_time_ns{server_binding_ip="0.0.0.0",server_binding_port="7070",server_binding_protocol="http"} 1
```

Author: josecelano

Cargo.lock

@@ -37,6 +37,7 @@ torrust-rest-tracker-api-core = { version = "3.0.0-develop", path = "../rest-tra
 torrust-server-lib = { version = "3.0.0-develop", path = "../server-lib" }
 torrust-tracker-clock = { version = "3.0.0-develop", path = "../clock" }
 torrust-tracker-configuration = { version = "3.0.0-develop", path = "../configuration" }
+torrust-tracker-metrics = { version = "3.0.0-develop", path = "../metrics" }
 torrust-tracker-primitives = { version = "3.0.0-develop", path = "../primitives" }
 torrust-udp-tracker-server = { version = "3.0.0-develop", path = "../udp-tracker-server" }
 tower = { version = "0", features = ["timeout"] }

packages/axum-rest-tracker-api-server/Cargo.toml

@@ -9,9 +9,9 @@ use bittorrent_tracker_core::torrent::repository::in_memory::InMemoryTorrentRepo
 use bittorrent_udp_tracker_core::services::banning::BanService;
 use serde::Deserialize;
 use tokio::sync::RwLock;
-use torrust_rest_tracker_api_core::statistics::services::get_metrics;
+use torrust_rest_tracker_api_core::statistics::services::{get_labeled_metrics, get_metrics};
 
-use super::responses::{metrics_response, stats_response};
+use super::responses::{labeled_metrics_response, labeled_stats_response, metrics_response, stats_response};
 
 #[derive(Deserialize, Debug, Default)]
 #[serde(rename_all = "lowercase")]
@@ -28,7 +28,7 @@ pub struct QueryParams {
     pub format: Option<Format>,
 }
 
-/// It handles the request to get the tracker statistics.
+/// It handles the request to get the tracker global metrics.
 ///
 /// By default it returns a `200` response with the stats in JSON format.
 ///
@@ -57,3 +57,30 @@ pub async fn get_stats_handler(
         None => stats_response(metrics),
     }
 }
+
+/// It handles the request to get the tracker extendable metrics.
+///
+/// By default it returns a `200` response with the stats in JSON format.
+///
+/// You can add the GET parameter `format=prometheus` to get the stats in
+/// Prometheus Text Exposition Format.
+#[allow(clippy::type_complexity)]
+pub async fn get_metrics_handler(
+    State(state): State<(
+        Arc<InMemoryTorrentRepository>,
+        Arc<RwLock<BanService>>,
+        Arc<bittorrent_http_tracker_core::statistics::repository::Repository>,
+        Arc<torrust_udp_tracker_server::statistics::repository::Repository>,
+    )>,
+    params: Query<QueryParams>,
+) -> Response {
+    let metrics = get_labeled_metrics(state.0.clone(), state.1.clone(), state.2.clone(), state.3.clone()).await;
+
+    match params.0.format {
+        Some(format) => match format {
+            Format::Json => labeled_stats_response(metrics),
+            Format::Prometheus => labeled_metrics_response(&metrics),
+        },
+        None => labeled_stats_response(metrics),
+    }
+}

packages/axum-rest-tracker-api-server/src/v1/context/stats/handlers.rs

@@ -1,7 +1,8 @@
 //! API resources for the [`stats`](crate::v1::context::stats)
 //! API context.
 use serde::{Deserialize, Serialize};
-use torrust_rest_tracker_api_core::statistics::services::TrackerMetrics;
+use torrust_rest_tracker_api_core::statistics::services::{TrackerLabeledMetrics, TrackerMetrics};
+use torrust_tracker_metrics::metric_collection::MetricCollection;
 
 /// It contains all the statistics generated by the tracker.
 #[derive(Serialize, Deserialize, Debug, PartialEq, Eq)]
@@ -116,6 +117,21 @@ impl From<TrackerMetrics> for Stats {
     }
 }
 
+/// It contains all the statistics generated by the tracker.
+#[derive(Serialize, Debug, PartialEq)]
+pub struct LabeledStats {
+    metrics: MetricCollection,
+}
+
+impl From<TrackerLabeledMetrics> for LabeledStats {
+    #[allow(deprecated)]
+    fn from(metrics: TrackerLabeledMetrics) -> Self {
+        Self {
+            metrics: metrics.metrics,
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use torrust_rest_tracker_api_core::statistics::metrics::Metrics;