C++ sysroot builder

This repository contains Bazel rules that leverage rules_distroless to build tiny sysroot tar files for a matrix of target platforms:

Distribution

Currently, only a single distribution is supported as a source of packages. In practice, the choice of distro doesn't matter, but the code allows you to add more distros easily.

• Debian 12 (bookworm)

Architectures

• amd64
• arm64

C++ standard libraries

• libstdc++ (GNU)
• libc++ (LLVM)

Obtaining a sysroot

There are multiple ways for obtaining sysroots:

1. Build the target of choice and put it into a cloud storage bucket The following targets can be built:

   • @sysroots//:sysroot_bookworm_libcxx_amd64
   • @sysroots//:sysroot_bookworm_libstdcxx_amd64
   • @sysroots//:sysroot_bookworm_libcxx_arm64
   • @sysroots//:sysroot_bookworm_libstdcxx_arm64

   $ bazel build @sysroots//:sysroot_bookworm_libcxx_amd64
     bazel-bin/sysroot_bookworm_libcxx_amd64.tar.zst
   

2. Download the container image and use docker export

   $ crane export --platform=linux/amd64 ghcr.io/malt3/sysroots/libcxx:bookworm ./sysroot.tar
   $ crane export --platform=linux/arm64 ghcr.io/malt3/sysroots/libstdcxx:bookworm ./sysroot.tar
   

3. Directly download an image layer as an http_archive in Bazel. For this, have a look at the example

Using this sysroot in Bazel

I recommend toolchains_llvm and static-clang. The example shows a way to set this up with the ability to target different C++ standard library implementations.