Merge #367: Improve docker UX

ec7bd7d fix: env var name. Wrong prefix (Jose Celano)
8936c6e feat!: continue running the tracker after creating default config file (Jose Celano)
702dd14 feat: allow to change the config.toml file path (Jose Celano)
0adf373 refactor: [#361] rename constants representing env vars (Jose Celano)
8a79fbe refactor: [#361] extract mod for configuration (Jose Celano)

Pull request description:

  Some minor improvements to make using docker and the app configuration a smoother experience.

Top commit has no ACKs.

Tree-SHA512: eef1d68b78e0a228714c926881e6a09f5c859632488fbf69fd5dcdc4d34e8654835afc32d4620af7d7753a99ee2a92d8ddc49f97e055ae72b4f987aad261609c

packages/configuration/src/lib.rs

@@ -228,14 +228,11 @@
 //!```
 use std::collections::{HashMap, HashSet};
 use std::net::IpAddr;
-use std::panic::Location;
-use std::path::Path;
 use std::str::FromStr;
 use std::sync::Arc;
 use std::{env, fs};
 
 use config::{Config, ConfigError, File, FileFormat};
-use log::warn;
 use serde::{Deserialize, Serialize};
 use serde_with::{serde_as, NoneAsEmptyString};
 use thiserror::Error;
@@ -414,17 +411,6 @@ pub enum Error {
         source: LocatedError<'static, dyn std::error::Error + Send + Sync>,
     },
 
-    /// If you run the tracker without providing the configuration (via the
-    /// `TORRUST_TRACKER_CONFIG` environment variable or configuration file),
-    /// the tracker will create a default configuration file but it will not
-    /// load it. It will return this error instead and you have to restart the
-    /// it.
-    #[error("Default configuration created at: `{path}`, please review and reload tracker, {location}")]
-    CreatedNewConfigHalt {
-        location: &'static Location<'static>,
-        path: String,
-    },
-
     /// Unable to load the configuration from the configuration file.
     #[error("Failed processing the configuration: {source}")]
     ConfigError { source: LocatedError<'static, ConfigError> },
@@ -502,31 +488,32 @@ impl Configuration {
     ///
     /// # Errors
     ///
-    /// Will return `Err` if `path` does not exist or has a bad configuration.
+    /// Will return `Err` if `path` does not exist or has a bad configuration.    
     pub fn load_from_file(path: &str) -> Result<Configuration, Error> {
         let config_builder = Config::builder();
 
         #[allow(unused_assignments)]
         let mut config = Config::default();
 
-        if Path::new(path).exists() {
-            config = config_builder.add_source(File::with_name(path)).build()?;
-        } else {
-            warn!("No config file found.");
-            warn!("Creating config file..");
-            let config = Configuration::default();
-            config.save_to_file(path)?;
-            return Err(Error::CreatedNewConfigHalt {
-                location: Location::caller(),
-                path: path.to_string(),
-            });
-        }
+        config = config_builder.add_source(File::with_name(path)).build()?;
 
         let torrust_config: Configuration = config.try_deserialize()?;
 
         Ok(torrust_config)
     }
 
+    /// Saves the default configuration at the given path.
+    ///
+    /// # Errors
+    ///
+    /// Will return `Err` if `path` is not a valid path or the configuration
+    /// file cannot be created.
+    pub fn create_default_configuration_file(path: &str) -> Result<Configuration, Error> {
+        let config = Configuration::default();
+        config.save_to_file(path)?;
+        Ok(config)
+    }
+
     /// Loads the configuration from the environment variable. The whole
     /// configuration must be in the environment variable. It contains the same
     /// configuration as the configuration file with the same format.

src/bootstrap/app.rs

@@ -11,11 +11,11 @@
 //! 2. Initialize static variables.
 //! 3. Initialize logging.
 //! 4. Initialize the domain tracker.
-use std::env;
 use std::sync::Arc;
 
 use torrust_tracker_configuration::Configuration;
 
+use super::config::initialize_configuration;
 use crate::bootstrap;
 use crate::shared::clock::static_time;
 use crate::shared::crypto::ephemeral_instance_keys;
@@ -55,35 +55,6 @@ pub fn initialize_static() {
     lazy_static::initialize(&ephemeral_instance_keys::RANDOM_SEED);
 }
 
-/// It loads the application configuration from the environment.
-///
-/// There are two methods to inject the configuration:
-///
-/// 1. By using a config file: `config.toml`. The file must be in the same folder where you are running the tracker.
-/// 2. Environment variable: `TORRUST_TRACKER_CONFIG`. The variable contains the same contents as the `config.toml` file.
-///
-/// Environment variable has priority over the config file.
-///
-/// Refer to the [configuration documentation](https://docs.rs/torrust-tracker-configuration) for the configuration options.
-///
-/// # Panics
-///
-/// Will panic if it can't load the configuration from either
-/// `./config.toml` file or the env var `TORRUST_TRACKER_CONFIG`.
-#[must_use]
-fn initialize_configuration() -> Configuration {
-    const CONFIG_PATH: &str = "./config.toml";
-    const CONFIG_ENV_VAR_NAME: &str = "TORRUST_TRACKER_CONFIG";
-
-    if env::var(CONFIG_ENV_VAR_NAME).is_ok() {
-        println!("Loading configuration from env var {CONFIG_ENV_VAR_NAME}");
-        Configuration::load_from_env_var(CONFIG_ENV_VAR_NAME).unwrap()
-    } else {
-        println!("Loading configuration from config file {CONFIG_PATH}");
-        Configuration::load_from_file(CONFIG_PATH).unwrap()
-    }
-}
-
 /// It builds the domain tracker
 ///
 /// The tracker is the domain layer service. It's the entrypoint to make requests to the domain layer.

src/bootstrap/config.rs

@@ -0,0 +1,69 @@
+//! Initialize configuration from file or env var.
+//!
+//! All environment variables are prefixed with `TORRUST_TRACKER_BACK_`.
+use std::env;
+use std::path::Path;
+
+use torrust_tracker_configuration::{Configuration, Error};
+
+// Environment variables
+
+/// The whole `config.toml` file content. It has priority over the config file.
+/// Even if the file is not on the default path.
+const ENV_VAR_CONFIG: &str = "TORRUST_TRACKER_CONFIG";
+
+/// The `config.toml` file location.
+pub const ENV_VAR_CONFIG_PATH: &str = "TORRUST_TRACKER_CONFIG_PATH";
+
+// Default values
+
+const ENV_VAR_DEFAULT_CONFIG_PATH: &str = "./config.toml";
+
+/// It loads the application configuration from the environment.
+///
+/// There are two methods to inject the configuration:
+///
+/// 1. By using a config file: `config.toml`.
+/// 2. Environment variable: `TORRUST_TRACKER_CONFIG`. The variable contains the same contents as the `config.toml` file.
+///
+/// Environment variable has priority over the config file.
+///
+/// Refer to the [configuration documentation](https://docs.rs/torrust-tracker-configuration) for the configuration options.
+///
+/// # Panics
+///
+/// Will panic if it can't load the configuration from either
+/// `./config.toml` file or the env var `TORRUST_TRACKER_CONFIG`.
+#[must_use]
+pub fn initialize_configuration() -> Configuration {
+    if env::var(ENV_VAR_CONFIG).is_ok() {
+        println!("Loading configuration from env var {ENV_VAR_CONFIG} ...");
+
+        Configuration::load_from_env_var(ENV_VAR_CONFIG).unwrap()
+    } else {
+        let config_path = env::var(ENV_VAR_CONFIG_PATH).unwrap_or_else(|_| ENV_VAR_DEFAULT_CONFIG_PATH.to_string());
+
+        println!("Loading configuration from configuration file: `{config_path}` ...");
+
+        load_from_file_or_create_default(&config_path).unwrap()
+    }
+}
+
+/// Loads the configuration from the configuration file. If the file does
+/// not exist, it will create a default configuration file and return an
+/// error.
+///
+/// # Errors
+///
+/// Will return `Err` if `path` does not exist or has a bad configuration.
+fn load_from_file_or_create_default(path: &str) -> Result<Configuration, Error> {
+    if Path::new(&path).is_file() {
+        Configuration::load_from_file(path)
+    } else {
+        println!("Missing configuration file.");
+        println!("Creating a default configuration file: `{path}` ...");
+        let config = Configuration::create_default_configuration_file(path)?;
+        println!("Please review the config file: `{path}` and restart the tracker if needed.");
+        Ok(config)
+    }
+}

src/bootstrap/mod.rs

@@ -6,5 +6,6 @@
 //! like cleaning torrents, and other jobs because they can be enabled/disabled depending on the configuration.
 //! For example, you can have more than one UDP and HTTP tracker, each server is executed like a independent job.
 pub mod app;
+pub mod config;
 pub mod jobs;
 pub mod logging;