Support variants.yml

[isuruf]

Bug:

Currently only conda_build_config.yaml is supported in https://github.com/conda-forge/staged-recipes/blob/main/.ci_support/build_all.py#L111

cc @wolfv

[wolfv]

Good point, will take a look.

[beckermr]

I'm confused. If we allow folks to use a variants.yaml instead of a conda build config, we're going to break smithy, the bot, and likely other things. Am I missing something?

[beckermr]

I've mentioned this before but I'll say it more explicitly. IMHO we want a drop-in replacement for conda-build that uses the new recipe format. We don't want to have to maintain two parallel tracks of infrastructure outside of the recipe itself.

[isuruf]

Isn't variants.yaml the new conda_build_config.yaml for recipe-v1?

[beckermr]

Idk but right now we use conda build to produce all of the ci support files when rendering with smithy. If we move to variants.yaml, we'll have to retool all of that at minimum.

[wolfv]

I think Nichita has done the work already, and variants.yaml will automatically be parsed by rattler-build when rendering for variant discovery.

[wolfv]

But we need to validate and make sure that this is what we want. I think supporting the old style conda_build_config.yaml is also doable (or even already works today thanks to smithy).