How to add build targets to the Rust toolchain in the builder image?

[tangowithfoxtrot]

In the README, there is an example that uses a MUSL target to create a statically-linked binary. I was just wondering, if that build target isn't already present in the default image, how would we add it?

For example, here is my repro-env.toml file:

[container]
image = "debian:trixie"

[packages]
system = "debian"
dependencies = ["ca-certificates", "musl-tools", "libc6-dev", "rust-all"]

I use this build command:

repro-env build -- cargo build --release --target aarch64-unknown-linux-musl

But the aarch64-unknown-linux-musl build target isn't available in the image by default, so I get the following error:

error[E0463]: can't find crate for `core`
  |
  = note: the `aarch64-unknown-linux-musl` target may not be installed
  = help: consider downloading the target with `rustup target add aarch64-unknown-linux-musl`

For more information about this error, try `rustc --explain E0463`.
error: could not compile `memchr` (lib) due to 1 previous error
warning: build failed, waiting for other jobs to finish...
error: could not compile `regex-syntax` (lib) due to 1 previous error
Error: Failed to execute in container: ["cargo", "build", "--release", "--target", "aarch64-unknown-linux-musl"]

Caused by:
    Podman command (["container", "exec", "-w", "/build", "--", "b3b41540bbdb4f6e48e5061ba27314ed868587817f3f16b4439cc0d755a0da47", "cargo", "build", "--release", "--target", "aarch64-unknown-linux-musl"]) failed to execute: ExitStatus(unix_wait_status(25856))

[kpcyrd]

hi!

I'm currently using an Arch Linux build environment for my statically linked binaries. There's a rust-aarch64-musl package that can be used together with musl-aarch64.

Before this was a thing, I explicitly selected a non-rust docker image, added rustup as a package and then installed an explicit toolchain version, as noted in the readme:

# select a specific Rust release so it's documented which one has been used
rustup default 1.80.1
rustup target add aarch64-unknown-linux-musl
rustup target add x86_64-unknown-linux-musl

I don't know if rustup target add resolves to a deterministic version with regular Rust images, but could be worth a try.

I asked somebody from the debian-rust team and apparently it's also possible to use the dpkg multiarch feature to make a different build target available, but I'm not sure if this is currently properly implemented in repro-env (you may need to generate your own repro-env.lock).

I hope this helps, let me know if you have trouble getting this to work!

[kpcyrd]

Ah sorry, the readme I was referring to is from a different repository (apt.vulns.xyz), specifically this version of it:

https://github.com/kpcyrd/apt-vulns-xyz/tree/c8584ad731ae9edff6a1d8f3d408d622649b46ad

I've now updated it to the new Arch Linux instructions.