Update and unify app

backend/Dockerfile

@@ -1,9 +1,23 @@
-FROM rust:1.73 as builder
-WORKDIR /usr/src/app
-COPY . .
-RUN cargo build --release
+FROM rust:1 AS chef 
+# We only pay the installation cost once, 
+# it will be cached from the second build onwards
+RUN cargo install cargo-chef 
+WORKDIR /app
 
-FROM alpine:latest
-RUN apk add --no-cache libgcc libstdc++
-COPY --from=builder /usr/src/app/target/release/qr-generator /usr/local/bin/qr-generator
-CMD ["qr-generator"]
+FROM chef AS planner
+COPY . .
+RUN cargo chef prepare  --recipe-path recipe.json
+
+FROM chef AS builder
+COPY --from=planner /app/recipe.json recipe.json
+# Build dependencies - this is the caching Docker layer!
+RUN cargo chef cook --release --recipe-path recipe.json
+# Build application
+COPY . .
+RUN cargo build --release --bin qr-generator
+
+# We do not need the Rust toolchain to run the binary!
+FROM debian:bookworm-slim AS runtime
+WORKDIR /app
+COPY --from=builder /app/target/release/qr-generator /usr/local/bin
+ENTRYPOINT ["/usr/local/bin/qr-generator"]