feat: [#1445] add logs for metrics initialization

Author: josecelano

Cargo.lock

@@ -21,6 +21,7 @@ serde = { version = "1", features = ["derive"] }
 serde_json = "1.0.140"
 thiserror = "2"
 torrust-tracker-primitives = { version = "3.0.0-develop", path = "../primitives" }
+tracing = "0.1.41"
 
 [dev-dependencies]
 approx = "0.5.1"

packages/metrics/Cargo.toml

@@ -8,6 +8,8 @@ pub mod sample;
 pub mod sample_collection;
 pub mod unit;
 
+pub const METRICS_TARGET: &str = "METRICS";
+
 #[cfg(test)]
 mod tests {
     /// It removes leading and trailing whitespace from each line, and empty lines.

packages/metrics/src/lib.rs

@@ -12,6 +12,7 @@ use super::prometheus::PrometheusSerializable;
 use crate::metric::description::MetricDescription;
 use crate::sample_collection::SampleCollection;
 use crate::unit::Unit;
+use crate::METRICS_TARGET;
 
 // code-review: serialize in a deterministic order? For example:
 // - First the counter metrics ordered by name.
@@ -56,7 +57,8 @@ impl MetricCollection {
 
     // Counter-specific methods
 
-    pub fn describe_counter(&mut self, name: &MetricName, _opt_unit: Option<Unit>, _opt_description: Option<MetricDescription>) {
+    pub fn describe_counter(&mut self, name: &MetricName, opt_unit: Option<Unit>, opt_description: Option<MetricDescription>) {
+        tracing::info!(target: METRICS_TARGET, type = "counter", name = name.to_string(), unit = ?opt_unit, description = ?opt_description);
         self.counters.ensure_metric_exists(name);
     }
 
@@ -97,7 +99,8 @@ impl MetricCollection {
 
     // Gauge-specific methods
 
-    pub fn describe_gauge(&mut self, name: &MetricName, _opt_unit: Option<Unit>, _opt_description: Option<MetricDescription>) {
+    pub fn describe_gauge(&mut self, name: &MetricName, opt_unit: Option<Unit>, opt_description: Option<MetricDescription>) {
+        tracing::info!(target: METRICS_TARGET, type = "gauge", name = name.to_string(), unit = ?opt_unit, description = ?opt_description);
         self.gauges.ensure_metric_exists(name);
     }
 

packages/metrics/src/metric_collection.rs

@@ -4,6 +4,7 @@
 //! The `Unit` enum is used to specify the unit of measurement for metrics.
 //!
 //! They were copied from the `metrics` crate, to allow future compatibility.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum Unit {
     Count,
     Percent,