feat!: [#938] add mandatory config options

Some configuration options are mandatory. The tracker will panic if the user doesn't provide an explicit value for them from one of the configuration sources: TOML or ENV VARS.

The mandatory options are:

```toml
[metadata]
schema_version = "2.0.0"

[logging]
threshold = "info"

[core]
private = false
listed = false
```

Author: josecelano

packages/configuration/src/lib.rs

@@ -303,6 +303,9 @@ pub enum Error {
 
     #[error("Unsupported configuration version: {version}")]
     UnsupportedVersion { version: Version },
+
+    #[error("Missing mandatory configuration option. Option path: {path}")]
+    MissingMandatoryOption { path: String },
 }
 
 impl From<figment::Error> for Error {

packages/configuration/src/v2_0_0/mod.rs

@@ -313,27 +313,33 @@ impl Configuration {
     }
 
     /// Loads the configuration from the `Info` struct. The whole
-    /// configuration in toml format is included in the `info.tracker_toml` string.
+    /// configuration in toml format is included in the `info.tracker_toml`
+    /// string.
     ///
-    /// Optionally will override the admin api token.
+    /// Configuration provided via env var has priority over config file path.
     ///
     /// # Errors
     ///
     /// Will return `Err` if the environment variable does not exist or has a bad configuration.
     pub fn load(info: &Info) -> Result<Configuration, Error> {
+        // Load configuration provided by the user, prioritizing env vars
         let figment = if let Some(config_toml) = &info.config_toml {
-            // Config in env var has priority over config file path
-            Figment::from(Serialized::defaults(Configuration::default()))
-                .merge(Toml::string(config_toml))
-                .merge(Env::prefixed(CONFIG_OVERRIDE_PREFIX).split(CONFIG_OVERRIDE_SEPARATOR))
+            Figment::from(Toml::string(config_toml)).merge(Env::prefixed(CONFIG_OVERRIDE_PREFIX).split(CONFIG_OVERRIDE_SEPARATOR))
         } else {
-            Figment::from(Serialized::defaults(Configuration::default()))
-                .merge(Toml::file(&info.config_toml_path))
+            Figment::from(Toml::file(&info.config_toml_path))
                 .merge(Env::prefixed(CONFIG_OVERRIDE_PREFIX).split(CONFIG_OVERRIDE_SEPARATOR))
         };
 
+        // Make sure user has provided the mandatory options.
+        Self::check_mandatory_options(&figment)?;
+
+        // Fill missing options with default values.
+        let figment = figment.join(Serialized::defaults(Configuration::default()));
+
+        // Build final configuration.
         let config: Configuration = figment.extract()?;
 
+        // Make sure the provided schema version matches this version.
         if config.metadata.schema_version != Version::new(VERSION_2_0_0) {
             return Err(Error::UnsupportedVersion {
                 version: config.metadata.schema_version,
@@ -343,6 +349,28 @@ impl Configuration {
         Ok(config)
     }
 
+    /// Some configuration options are mandatory. The tracker will panic if
+    /// the user doesn't provide an explicit value for them from one of the
+    /// configuration sources: TOML or ENV VARS.
+    ///
+    /// # Errors
+    ///
+    /// Will return an error if a mandatory configuration option is only
+    /// obtained by default value (code), meaning the user hasn't overridden it.
+    fn check_mandatory_options(figment: &Figment) -> Result<(), Error> {
+        let mandatory_options = ["metadata.schema_version", "logging.threshold", "core.private", "core.listed"];
+
+        for mandatory_option in mandatory_options {
+            figment
+                .find_value(mandatory_option)
+                .map_err(|_err| Error::MissingMandatoryOption {
+                    path: mandatory_option.to_owned(),
+                })?;
+        }
+
+        Ok(())
+    }
+
     /// Saves the configuration to the configuration file.
     ///
     /// # Errors
@@ -496,14 +524,25 @@ mod tests {
     }
 
     #[test]
-    fn configuration_should_use_the_default_values_when_an_empty_configuration_is_provided_by_the_user() {
+    fn configuration_should_use_the_default_values_when_only_the_mandatory_options_are_provided_by_the_user_via_toml_file() {
         figment::Jail::expect_with(|jail| {
-            jail.create_file("tracker.toml", "")?;
+            jail.create_file(
+                "tracker.toml",
+                r#"
+                [metadata]
+                schema_version = "2.0.0"
+
+                [logging]
+                threshold = "info"
 
-            let empty_configuration = String::new();
+                [core]
+                listed = false
+                private = false
+            "#,
+            )?;
 
             let info = Info {
-                config_toml: Some(empty_configuration),
+                config_toml: None,
                 config_toml_path: "tracker.toml".to_string(),
             };
 
@@ -515,10 +554,49 @@ mod tests {
         });
     }
 
+    #[test]
+    fn configuration_should_use_the_default_values_when_only_the_mandatory_options_are_provided_by_the_user_via_toml_content() {
+        figment::Jail::expect_with(|_jail| {
+            let config_toml = r#"
+                [metadata]
+                schema_version = "2.0.0"
+
+                [logging]
+                threshold = "info"
+
+                [core]
+                listed = false
+                private = false
+            "#
+            .to_string();
+
+            let info = Info {
+                config_toml: Some(config_toml),
+                config_toml_path: String::new(),
+            };
+
+            let configuration = Configuration::load(&info).expect("Could not load configuration from file");
+
+            assert_eq!(configuration, Configuration::default());
+
+            Ok(())
+        });
+    }
+
     #[test]
     fn default_configuration_could_be_overwritten_from_a_single_env_var_with_toml_contents() {
         figment::Jail::expect_with(|_jail| {
             let config_toml = r#"
+                [metadata]
+                schema_version = "2.0.0"
+
+                [logging]
+                threshold = "info"
+
+                [core]
+                listed = false
+                private = false
+
                 [core.database]
                 path = "OVERWRITTEN DEFAULT DB PATH"
             "#
@@ -543,6 +621,16 @@ mod tests {
             jail.create_file(
                 "tracker.toml",
                 r#"
+                [metadata]
+                schema_version = "2.0.0"
+
+                [logging]
+                threshold = "info"
+
+                [core]
+                listed = false
+                private = false
+
                 [core.database]
                 path = "OVERWRITTEN DEFAULT DB PATH"
             "#,

share/default/config/tracker.container.mysql.toml

@@ -3,6 +3,13 @@ app = "torrust-tracker"
 purpose = "configuration"
 schema_version = "2.0.0"
 
+[logging]
+threshold = "info"
+
+[core]
+listed = false
+private = false
+
 [core.database]
 driver = "mysql"
 path = "mysql://db_user:db_user_secret_password@mysql:3306/torrust_tracker"

share/default/config/tracker.container.sqlite3.toml

@@ -3,6 +3,13 @@ app = "torrust-tracker"
 purpose = "configuration"
 schema_version = "2.0.0"
 
+[logging]
+threshold = "info"
+
+[core]
+listed = false
+private = false
+
 [core.database]
 path = "/var/lib/torrust/tracker/database/sqlite3.db"
 

share/default/config/tracker.development.sqlite3.toml

@@ -3,6 +3,13 @@ app = "torrust-tracker"
 purpose = "configuration"
 schema_version = "2.0.0"
 
+[logging]
+threshold = "info"
+
+[core]
+listed = false
+private = false
+
 [[udp_trackers]]
 bind_address = "0.0.0.0:6969"
 

share/default/config/tracker.e2e.container.sqlite3.toml

@@ -3,6 +3,13 @@ app = "torrust-tracker"
 purpose = "configuration"
 schema_version = "2.0.0"
 
+[logging]
+threshold = "info"
+
+[core]
+listed = false
+private = false
+
 [core.database]
 path = "/var/lib/torrust/tracker/database/sqlite3.db"
 

share/default/config/tracker.udp.benchmarking.toml

@@ -7,6 +7,8 @@ schema_version = "2.0.0"
 threshold = "error"
 
 [core]
+listed = false
+private = false
 remove_peerless_torrents = false
 tracker_usage_statistics = false