Use a base OS to run binary instead of Rust runtime (#67)

The Rust runtime for a docker image is large as it includes the language's tooling. It is not needed to run a Rust binary file. This replaces running the binary with the full runtime with a base OS (Debian) to reduce the size of the Docker image.

src/deployment/ssr.md

@@ -43,17 +43,23 @@ COPY . .
 # Build the app
 RUN cargo leptos build --release -vv
 
-FROM rustlang/rust:nightly-bullseye as runner
+FROM debian:bookworm-slim as runtime
+WORKDIR /app
+RUN apt-get update -y \
+  && apt-get install -y --no-install-recommends openssl ca-certificates \
+  && apt-get autoremove -y \
+  && apt-get clean -y \
+  && rm -rf /var/lib/apt/lists/*
 
 # -- NB: update binary name from "leptos_start" to match your app name in Cargo.toml --
 # Copy the server binary to the /app directory
 COPY --from=builder /app/target/release/leptos_start /app/
 
 # /target/site contains our JS/WASM/CSS, etc.
 COPY --from=builder /app/target/site /app/site
+
 # Copy Cargo.toml if it’s needed at runtime
 COPY --from=builder /app/Cargo.toml /app/
-WORKDIR /app
 
 # Set any required env variables and
 ENV RUST_LOG="info"