Add scripts to build native binary (using a container)

[vorburger]

Fixes #894 and fixes #868!

As is, this doesn't work yet, launching ./build-natives.sh fails with:

[ERROR] Failed to execute goal org.graalvm.buildtools:native-maven-plugin:0.9.13:build (build-native) on project google-java-format: 'gu' tool wasn't found. This probably means that JDK at isn't a GraalVM distribution. -> [Help 1]

What this gu tool which apparently comes with a GraalVM distribution, but isn't included in a Graal container base image?!

@fmeum @cushon perhaps you would know and like to chime in here?

PS: This includes #1044, so don't "squash merge" this PR, but merge that one (1044) first, then "rebase merge" this one, and only the 2nd commit would be merged, and 1st one dropped. (Or I could rebase this after that is merged, so this is cleaner, if requested.)

[vorburger]

What this gu tool which apparently comes with a GraalVM distribution, but isn't included in a Graal container base image?!

According to oracle/graal#1868, gu is no longer available / needed?

Perhaps bumping the version of org.graalvm.buildtools:native-maven-plugin helps? I'll try...

[vorburger]

Hah! It now "works" - kind of. How cool is this?

To make this fully ready for review as-is, from my side, I would need to do some more work to change the script to not use volumes in docker build, which works for locally, for me, on Fedora, with Podman; but with Docker, on Debian in a GitHub action, apparently docker build cannot use volumes?! How dumb is that... But it should be possible to rewrite it differently, probably in the end using both docker build and docker run. (Or with multi stage images, e.g. as explained here or here; although that wouldn't really work for the cache I'm using.)

Before spending a bit more time to do that ^^^ I would love a signal from reviewers / project committers if this would be merged, when green?

@cushon @cpovirk

[vorburger]

https://docs.docker.com/build/guide/mounts/ for RUN --mount=type=cache,target=/root/.m2/ is cute, and is another better more "native Docker" way to solve ^^^ this which I previously didn't know about but learnt here. (Nice job of your old colleagues @teivah! 👋🏽)

With that, this is now fully ready for review as-is, from my side.

[cushon]

Thanks for investigating this!

Is https://github.com/graalvm/setup-graalvm a potential alternative to using docker to set up GraalVM?

[vorburger]

Is https://github.com/graalvm/setup-graalvm a potential alternative to using docker to set up GraalVM?

It might - I hadn't seen (searched for) that approach.

Why I personally prefer this route over a GitHub Actions based approach is that this make it very easy to use locally:

Anyone who has Docker, even e.g. on a Mac or Windows, can launch ./build-natives.sh - and, voilà, natives magically come out! Without needing to worry about having anything else installed. (The Mac or Windows cross compilation is orthogonal, of course.)

With GitHub Actions, it's "only possible on (and "locked into") GitHub", which... I personally don't like much.

What do you think?

[cushon]

Thanks for the background. I think my preference here as a maintainer is to try to use the dependencies and process we already have, vs. replacing it with a new one. GitHub Actions isn't perfect, but one concrete benefit here is that it would provide a way to support mac binaries.

[vorburger]

OK, makes sense; then I'll try that approach! Some other day though, and I'll raise a separate new PR.