Dockerfile.glibc-static-rust

# Description: Static linking of rustc on debian buster with glibc.
# Notes:
#   * Obligatory rustc docs: https://doc.rust-lang.org/reference/linkage.html
#   * proc-macro does not seem to work with static linking, regardless of libc flavor.
#     cf. https://github.com/rust-lang/cargo/issues/7563#issuecomment-553526254
#   * traditionally, to perform static linking static libraries are needed, hence the libgcc-8-dev install below.
#   * static linking is the default with musl and rustc afaict, hence builds on, say, alpine
#     should automatically be static, whereas for glibc we need to pass `-C target-feature=+crt-static`
#     to `RUSTFLAGS`. You can alternatively place this in your `Cargo.toml` under the `rustflags` key, e.g.
#     ```
#     <snip>
#     rustflags = ["-C", "target-feature=+crt-static"]
#     <snip>
#     ```
#   * glibc isn't necessarily conducive to static linking like musl.
#     cf. https://stackoverflow.com/a/26306630/2748415
#   * you'll need to consider how licensing plays into the picture.
#     cf. https://stackoverflow.com/questions/11693320/linking-glibc-statically-and-proprietary-software-licensing

FROM debian:buster

# Dependencies.
RUN apt update -y && apt install -y libgcc-8-dev curl build-essential file binutils
RUN ls /usr/lib/x86_64-linux-gnu*/*.a
RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- --default-toolchain none -y

# Install nightly as the +crt-static feature does not yet seem to be recognized on stable.
RUN . $HOME/.cargo/env && \
      echo $PATH && \
      rustup toolchain install nightly-2020-12-20 --profile minimal && \
      rustup default nightly-2020-12-20 && \
      cargo new example && \
      cd example && \
      RUSTFLAGS="-C target-feature=+crt-static" cargo build

# Multiple ways to confirm the resulting binary is statically linked ...
RUN cd example && \
      file target/debug/example; \
      ldd target/debug/example; \
      readelf --program-headers --wide target/debug/example; \
      readelf -x .interp target/debug/example