feat: use configuration.yaml to setup variables

src/configuration.rs

@@ -0,0 +1,25 @@
+#[derive(serde::Deserialize)]
+pub struct Settings {
+    pub database: DatabaseSettings,
+    pub application_port: u16,
+}
+
+#[derive(serde::Deserialize)]
+pub struct DatabaseSettings {
+    pub username: String,
+    pub password: String,
+    pub port: u16,
+    pub host: String,
+    pub database_name: String,
+}
+
+pub fn get_configuration() -> Result<Settings, config::ConfigError> {
+    let settings = config::Config::builder()
+        .add_source(config::File::new(
+            "configuration.yaml",
+            config::FileFormat::Yaml,
+        ))
+        .build()?;
+
+    settings.try_deserialize::<Settings>()
+}

src/main.rs

@@ -1,10 +1,15 @@
 use std::net::TcpListener;
 
-use email_newsletter_api::startup;
+use email_newsletter_api::{configuration::get_configuration, startup};
 
 #[tokio::main]
 async fn main() -> Result<(), std::io::Error> {
-    let listener = TcpListener::bind("127.0.0.1:8000").expect("Failed to bind to port 8000");
+    let configuration = get_configuration().expect("Failed to read configuration");
+
+    let port_number = configuration.application_port;
+
+    let listener = TcpListener::bind(format!("127.0.0.1:{}", port_number))
+        .unwrap_or_else(|_| panic!("Can't bind to port {} at localhost", port_number));
 
     // Move the error up the call stack
     // otherwise await for the HttpServer