Allow deploying nix-darwin machines.

[vifino]

Hey.
I like colmena and would like to use it for my darwin machines as well.

colmena should probably have a way to use darwinSystem instead of nixosSystem. I am unsure how one should select which one to use, but it's certainly a requirement if one wants to use nix-darwin to use macOS-specific packages and configuration.

I'll gladly help, but I'm really not that great in Nix.

[zhaofengli]

This is an interesting idea that I've been thinking about for a while. To help with the general case, we can have the concept of profile types which define how a profile (NixOS, home-manager, nix-darwin, etc.) can be evaluated and activated, like the implementation in deploy-rs. I haven't had the time to actually implement it, though.

[steveej]

@zhaofengli

like the implementation in deploy-rs.

just came by here and the link refers to the rust-lang/cargo instead of deploy-rs; probably a mistaken paste at least i can't see the relationship 😄

[johnalotoski]

Also interested in this feature.

[frobware]

Also interested in this feature.

[zhaofengli]

I'm gradually moving to macOS for desktop use and am working on this.