# Pin the Rust toolchain version used in the build stage.
ARG RUST_VERSION=1.92

# Name of the compiled binary produced by Cargo (must match Cargo.toml package name).
ARG APP_NAME=paste

################################################################################
# Build stage (DOI Rust image)
# This stage compiles the application.
################################################################################

FROM docker.io/library/rust:${RUST_VERSION}-alpine AS build

# Re-declare args inside the stage if you want to use them here.
ARG APP_NAME

# All build steps happen inside /app.
WORKDIR /app

# Install build dependencies needed to compile Rust crates on Alpine
RUN apk add --no-cache clang lld musl-dev git

# Build the application 
RUN --mount=type=bind,source=src,target=src \
    --mount=type=bind,source=Cargo.toml,target=Cargo.toml \
    --mount=type=bind,source=Cargo.lock,target=Cargo.lock \
    --mount=type=cache,target=/app/target/ \
    --mount=type=cache,target=/usr/local/cargo/git/db \
    --mount=type=cache,target=/usr/local/cargo/registry/ \
    cargo build --locked --release && \
    cp ./target/release/$APP_NAME /bin/server

################################################################################
# Runtime stage (DOI Alpine image)
# This stage runs the already-compiled binary with minimal dependencies.
################################################################################

FROM docker.io/library/alpine:3.18 AS final

# Create a non-privileged user (recommended best practice)
ARG UID=10001
RUN adduser \
    --disabled-password \
    --gecos "" \
    --home "/nonexistent" \
    --shell "/sbin/nologin" \
    --no-create-home \
    --uid "${UID}" \
    imnyang

# Drop privileges for runtime.
USER imnyang

# Copy only the compiled binary from the build stage.
COPY --from=build /bin/server /app/

# Rocket: listen on all interfaces inside the container.
ENV ROCKET_ADDRESS=0.0.0.0

# Document the port your app listens on.
EXPOSE 8000

# Start the application.
CMD ["/app/server"]