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.

.Dockerignore

@@ -1,5 +1,8 @@
-target
+target/
 .vscode
-tests
+tests/
 .git
 .gitignore
+.env
+Dockerfile
+migrations/

Dockerfile

@@ -1,11 +1,21 @@
-FROM rust:1.56
+FROM rust:1.56-slim AS builder
 
 WORKDIR /app
-
 COPY . .
+
 ENV SQLX_OFFLINE true
 RUN cargo build --release
 
+FROM debian:bullseye-slim AS runtime
+
+WORKDIR /app
+
+# Install dependancies required
+RUN apt update -y && apt install -y --no-install-recommends openssl && apt autoremove -y && apt clean -y && rm -rf /var/lib/apt/lists/*
+
+# Copy the fully built binary and configuration to the image
+COPY --from=builder /app/target/release/mail_app mail_app
+COPY configuration configuration 
 ENV APP_ENVIRONMENT production
 
-ENTRYPOINT ["./target/release/mail_app"]
+ENTRYPOINT ["./mail_app"]

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;