ylecornec / gazelle_nixos_repro

Similarly to what is done in rules_haskell, we would like to setup buildifier in a project that supports NixOS as well as other linux platforms (that may or may not have nix installed globally).

There are multiple cases:

• On NixOS we cannot use toolchains downloaded by rules_go and want to use a toolchain installed via rules_nixpkgs using nixpkgs_go_configure.
• On regular linux without nix installed we want to use a toolchain downloaded by rules_go.
• On regular linux with nix installed both would work so I think it's ultimately up to the project to decide. Here, similarly to what we do in rules_haskell, we would like to use the nix toolchain iff the user uses a nix shell provided with the project (i.e. if the IN_NIX_SHELL variable is set).

Usage

To use the nix toolchain (required on NixOS):

IN_NIX_SHELL=1 bazel build //:buildifier --host_platform=@rules_nixpkgs_core//platforms:host

To use the toolchain downloaded by rules_go (required if nix is not installed):

bazel build //:buildifier

Toolchains declared by rules_nixpkgs_go

I did not try it yet, but with this custom tag api, the rules_nixpkgs_go module could also register toolchains itself on platforms where nix is supported. And users would have a way to override these if needed, by declaring their own host, download or custom toolchain.

versions

bazel version = 6.1.0