Run invariance tests on `alpine` / `musl`

[JanCBrammer]

We're not running invariance tests on alpine due to problems with (pip) installing RDKit (

InChI/.github/workflows/ci.yml

Line 58 in 261682f

# FIXME: We don't run invariance test on alpine yet because of difficulties with RDKit installation.

).
Either don't run invariance tests on alpine (decision) or find way to install RDKit (preferably pre-built due to long build times).

[giallu]

Out of curiosity, why do you want tests to run on that specific image?

[flange-ipb]

I'm kind of responsible for introducing alpine in the CI via #6.

Alpine itself is a popular Docker base image and uses musl as C standard library. I guess Busybox would also be an appropriate choice. Adding musl to Debian/Ubuntu would mean a bit of work.

Why testing with musl?

• musl is used as standard library by Emscripten, the compiler employed by the InChI Web demo to cross-compile InChI to Wasm. So testing with musl gives me more confidence in the Wasm build.
• Is there any interest in using musl instead of glibc for cheminformatics? I've only seen rdkit-pypi#72 so far. (BTW: That's the reason why this issue exists. 😉)

[giallu]

@flange-ipb hey, that's super interesting, thanks for sharing the origin of this.

So if testing requires a build of rdkit for alpine, maybe something like https://github.com/daverona/alpine-rdkit or https://github.com/kubor/alpine-rdkit can help?

Probably @greglandrum can suggest the easiest path forward and avoid some trial/error on InChI's part.