feat: log final config after processing all config sources

We print to logs the final configuration used to run the tracker (after Figment processes
all sources):

```output
Loading extra configuration from file: `storage/tracker/etc/tracker.toml` ...
2024-07-01T15:29:09.785334Z  INFO torrust_tracker::bootstrap::logging: Logging initialized
2024-07-01T15:29:09.785862Z  INFO torrust_tracker::bootstrap::app: Configuration:
 {
  "logging": {
    "log_level": "info"
  },
  "core": {
    "announce_policy": {
      "interval": 120,
      "interval_min": 120
    },
    "database": {
      "driver": "Sqlite3",
      "path": "./storage/tracker/lib/database/sqlite3.db"
    },
    "inactive_peer_cleanup_interval": 600,
    "listed": false,
    "net": {
      "external_ip": "0.0.0.0",
      "on_reverse_proxy": false
    },
    "private": true,
    "tracker_policy": {
      "max_peer_timeout": 900,
      "persistent_torrent_completed_stat": false,
      "remove_peerless_torrents": true
    },
    "tracker_usage_statistics": true
  },
  "udp_trackers": null,
  "http_trackers": null,
  "http_api": null,
  "health_check_api": {
    "bind_address": "127.0.0.1:1313"
  }
}
2024-07-01T15:29:09.785879Z  WARN torrust_tracker::app: No services enabled in configuration
2024-07-01T15:29:09.785920Z  INFO torrust_tracker::app: No UDP blocks in configuration
2024-07-01T15:29:09.785923Z  INFO torrust_tracker::app: No HTTP blocks in configuration
2024-07-01T15:29:09.785924Z  INFO torrust_tracker::app: No API block in configuration
2024-07-01T15:29:09.785941Z  INFO HEALTH CHECK API: Starting on: http://127.0.0.1:1313
2024-07-01T15:29:09.786035Z  INFO HEALTH CHECK API: Started on: http://127.0.0.1:1313
```

packages/configuration/src/lib.rs

@@ -111,17 +111,17 @@ impl Info {
         let env_var_config_toml_path = ENV_VAR_CONFIG_TOML_PATH.to_string();
 
         let config_toml = if let Ok(config_toml) = env::var(env_var_config_toml) {
-            println!("Loading configuration from environment variable:\n {config_toml}");
+            println!("Loading extra configuration from environment variable:\n {config_toml}");
             Some(config_toml)
         } else {
             None
         };
 
         let config_toml_path = if let Ok(config_toml_path) = env::var(env_var_config_toml_path) {
-            println!("Loading configuration from file: `{config_toml_path}` ...");
+            println!("Loading extra configuration from file: `{config_toml_path}` ...");
             config_toml_path
         } else {
-            println!("Loading configuration from default configuration file: `{default_config_toml_path}` ...");
+            println!("Loading extra configuration from default configuration file: `{default_config_toml_path}` ...");
             default_config_toml_path
         };
 

packages/configuration/src/v2/mod.rs

@@ -346,10 +346,26 @@ impl Configuration {
     }
 
     /// Encodes the configuration to TOML.
+    ///
+    /// # Panics
+    ///
+    /// Will panic if it can't be converted to TOML.
+    #[must_use]
     fn to_toml(&self) -> String {
         // code-review: do we need to use Figment also to serialize into toml?
         toml::to_string(self).expect("Could not encode TOML value")
     }
+
+    /// Encodes the configuration to JSON.
+    ///
+    /// # Panics
+    ///
+    /// Will panic if it can't be converted to JSON.
+    #[must_use]
+    pub fn to_json(&self) -> String {
+        // code-review: do we need to use Figment also to serialize into json?
+        serde_json::to_string_pretty(self).expect("Could not encode JSON value")
+    }
 }
 
 #[cfg(test)]

src/bootstrap/app.rs

@@ -15,6 +15,7 @@ use std::sync::Arc;
 
 use torrust_tracker_clock::static_time;
 use torrust_tracker_configuration::Configuration;
+use tracing::info;
 
 use super::config::initialize_configuration;
 use crate::bootstrap;
@@ -26,8 +27,11 @@ use crate::shared::crypto::ephemeral_instance_keys;
 #[must_use]
 pub fn setup() -> (Configuration, Arc<Tracker>) {
     let configuration = initialize_configuration();
+
     let tracker = initialize_with_configuration(&configuration);
 
+    info!("Configuration:\n{}", configuration.to_json());
+
     (configuration, tracker)
 }