Optimize caching in Dockerfile

Dockerfile

@@ -1,18 +1,56 @@
+##################
+### BASE STAGE ###
+##################
+FROM rust:1.53 as base
+
+# Install build dependencies
+RUN cargo install strip_cargo_version
+RUN rustup target add x86_64-unknown-linux-musl
+
+WORKDIR /app
+RUN mkdir cli lib server
+
+
+###########################
+### STRIP-VERSION STAGE ###
+###########################
+FROM base as strip-version
+
+# Strip version from Cargo.*
+# This avoids cache invalidations (ergo rebuilding all deps) when bumping the version number
+COPY Cargo.lock Cargo.toml ./
+COPY server/Cargo.toml ./server/
+COPY cli/Cargo.toml ./cli/
+COPY lib/Cargo.toml ./lib/
+RUN strip_cargo_version
+
+
 ###################
 ### BUILD STAGE ###
 ###################
-FROM rust:1.51 as build_stage
+FROM base as build_stage
 
-# Install build dependencies
-RUN rustup target add x86_64-unknown-linux-musl
+RUN cargo init --bin server
+RUN cargo init --lib lib
+
+# Create a dummy binary for pre-compiling dependencies (for caching)
+COPY --from=strip-version /app/server/Cargo.toml /app/server/
+COPY --from=strip-version /app/lib/Cargo.toml /app/lib/
+COPY --from=strip-version /app/cli/Cargo.toml /app/cli/
+COPY --from=strip-version /app/Cargo.lock /app/Cargo.toml /app/
 
-# Build project
-WORKDIR /app
-COPY . .
 WORKDIR /app/server
 RUN cargo build --release --target x86_64-unknown-linux-musl
+
+# Copy actual source files
 WORKDIR /app
-RUN strip target/x86_64-unknown-linux-musl/release/stl
+COPY . .
+
+# Compile final binary
+WORKDIR /app/server
+RUN cargo build --release --target x86_64-unknown-linux-musl
+RUN strip /app/target/x86_64-unknown-linux-musl/release/stl
+
 
 ########################
 ### PRODUCTION STAGE ###