Promote x86_64-linux-musl to tier 1 platform

[straight-shoota]

x86_64-linux-musl is currently a tier 2 platform. With #7420 merged, automatic testing is now set up for this platform. Since Alpine Linux is already used in the compiler build workflow, it is naturally a core platform for Crystal.

Binary releases have already been provided for a long time in form of the generic Linux tarball.
That works for now, but a dedicated binary release which includes static libraries linked against musl-libc would be preferrable (see crystal-lang/distribution-scripts#29 (comment)). We might want to implement that first before moving to tier 1. But apart from that, I don't think there's anything standing in the way of promotion.

[RX14]

Don't we still have some hacks around exceptions? Or is the shards require "llvm" not neccesary any more?

[j8r]

@RX14 That's not really linked to the platform itself, that's static linking, which appears to be only supported on Alpine: #4276
On glibc based distribution static linking is not supported at all.

[stakach]

this dedicated binary release would be amazing

[beta-ziliani]

After revamping the platform support page, this issue came forward: we seem to have everything ticked to make x86_64-linux-musl a Tier 1 platform, except that, quoting the description of this issue, "a dedicated binary release which includes static libraries linked against musl-libc would be preferrable".

I might be wrong, but I consider this a "nice to have" but not really a blocking aspect. We are providing binaries that successfully run tests, so I consider this platform to be in Tier 1.

If that's agreed, we can proceed with crystal-lang/crystal-book#679

[stakach]

it would be nice to be able to install crystal via the alpine package manager - not sure if this is an official source?
https://pkgs.alpinelinux.org/packages?name=crystal&branch=edge&repo=&arch=&maintainer=

but that should be a sperate issue and otherwise agree with you and have not had any issues using crystal on musl and all our production releases run on it.

[jirutka]

Yes, we do package crystal for x86_64 and aarch64 in Alpine Linux, since Alpine v3.8 (2020). I’m the maintainer of this package. https://pkgs.alpinelinux.org/packages?name=crystal is the official source.

[stakach]

sweet! good to know @jirutka
seems like there is nothing holding it back from Teir 1 then as the binaries are available via the alpine package manager

tar.gz files available
https://dl-cdn.alpinelinux.org/alpine/edge/community/x86_64/
https://dl-cdn.alpinelinux.org/alpine/edge/community/x86_64/crystal-1.7.3-r0.apk

EDIT: looks like those are dynamically linked to /lib/ld-musl-x86_64.so.1
which i guess makes sense for that platform - but probably not too hard to generate a static binary as part of this workflow?
Maybe have a crystal-<version>-static musl release?

[straight-shoota]

@stakach For the record: Package availability in downstream repositories is explicitly not required for Tier 1. The Crystal project does not have any direct control over that anyway.
Also note that x86_64-linux-musl is more than Alpine Linux. It is probably the most prominent but certainly not the only distribution using musl libc.

The generic binaries made available at https://github.com/crystal-lang/crystal/releases should work on any x86_64-linux platform and thus fulfill the "official binary releases are provided" requirement.