Very large docker image size optimisations

without cross compiling to linux-musl, optimise image by compiling it on a slim rust image and then transferring only the binary over to a debian-slim image.

src/main.rs

@@ -1,8 +1,10 @@
+use std::net::TcpListener;
+use sqlx::PgPool;
+use sqlx::postgres::PgPoolOptions;
+
 use mail_app::startup::run;
 use mail_app::configuration::get_configuration;
 use mail_app::telemetry::{get_subscriber, init_subscriber};
-use std::net::TcpListener;
-use sqlx::PgPool;
 
 #[actix_web::main]
 async fn main() -> std::io::Result<()> {
@@ -13,7 +15,9 @@ async fn main() -> std::io::Result<()> {
     let configuration = get_configuration().expect("Failed to read configuration data.");
 
     // Configure connection to database for our startup
-    let connection_pool = PgPool::connect_lazy(&configuration.database.connection_string())
+    let connection_pool = PgPool::new()
+        .connect_timeout(std::time::Duration::from_secs(2))
+        .connect(&configuration.database.connection_string())
         .expect("Failed to connect to Postgres.");
 
     // Take port from settings file

src/startup.rs

@@ -1,6 +1,6 @@
 use actix_web::{web, App, HttpServer};
 use actix_web::dev::Server;
-use actix_web::web::Data;
+// use actix_web::web::Data;
 use std::net::TcpListener;
 use sqlx::PgPool;
 use tracing_actix_web::TracingLogger;