feat: add Rust example

example-rust/Dockerfile

@@ -0,0 +1,68 @@
+# syntax=docker/dockerfile:1
+
+#
+# ---- Builder Stage ----
+#
+# ARG TARGETPLATFORM is an automatic variable provided by Docker buildx.
+# It will be 'linux/amd64' or 'linux/arm64' depending on the --platform flag.
+# We are setting a default value for builds that don't use the --platform flag.
+ARG TARGETPLATFORM=linux/amd64
+
+# Use a builder image with Rust installed.
+FROM rust:1-alpine AS build
+
+# Set build-time arguments that will be used in subsequent commands.
+# This makes the value available inside the build stage.
+ARG TARGETPLATFORM
+
+# Install Zig, which will act as a universal C cross-compiler,
+# then install cargo-zigbuild to integrate it with Cargo.
+RUN apk add --no-cache zig build-base && \
+    cargo install cargo-zigbuild
+
+# Add the cargo bin directory to the PATH to make cargo-zigbuild available.
+ENV PATH="/root/.cargo/bin:${PATH}"
+
+# Set the working directory.
+WORKDIR /app
+
+# Copy the Cargo files first to leverage Docker's layer caching.
+COPY container_src/Cargo.toml container_src/Cargo.lock ./
+
+# This single RUN command determines the correct Rust target, installs it,
+# and builds the project's dependencies using the robust cargo-zigbuild.
+RUN case ${TARGETPLATFORM} in \
+    "linux/amd64") RUST_TARGET="x86_64-unknown-linux-musl" ;; \
+    "linux/arm64") RUST_TARGET="aarch64-unknown-linux-musl" ;; \
+    esac && \
+    rustup target add ${RUST_TARGET} && \
+    mkdir -p src && \
+    echo "fn main() {}" > src/main.rs && \
+    cargo zigbuild --release --target ${RUST_TARGET}
+
+# Now, copy the actual source code. This will be a separate layer.
+COPY container_src/src/ ./src/
+
+# Build the final application and create a stable symlink to the binary.
+RUN case ${TARGETPLATFORM} in \
+    "linux/amd64") RUST_TARGET="x86_64-unknown-linux-musl" ;; \
+    "linux/arm64") RUST_TARGET="aarch64-unknown-linux-musl" ;; \
+    esac && \
+    rm -f target/${RUST_TARGET}/release/deps/server* && \
+    cargo zigbuild --release --target ${RUST_TARGET} && \
+    ln -s /app/target/${RUST_TARGET}/release/server /app/server
+
+#
+# ---- Final Stage ----
+#
+# Use a minimal 'scratch' image for the final container.
+FROM scratch
+
+# Copy the built binary using the stable symlink created in the build stage.
+COPY --from=build /app/server /server
+
+# Expose the port the application will listen on.
+EXPOSE 8080
+
+# Set the entrypoint for the container.
+CMD ["/server"]