# nix-homebrew (WIP)

`nix-homebrew` manages Homebrew installations on macOS using [nix-darwin](https://github.com/LnL7/nix-darwin).
It pins the Homebrew version and optionally allows for declarative specification of taps.

## Quick Start

First of all, you must have [nix-darwin](https://github.com/LnL7/nix-darwin) configured already.
Add the following to your Flake inputs:

```nix
{
  inputs = {
    nix-homebrew.url = "github:zhaofengli-wip/nix-homebrew";

    # Optional: Declarative tap management
    homebrew-core = {
      url = "github:homebrew/homebrew-core";
      flake = false;
    };
    homebrew-cask = {
      url = "github:homebrew/homebrew-cask";
      flake = false;
    };

    # (...)
  };
}
```

Then, Homebrew can be installed with:

```nix
{
  output = { self, nix-darwin, nix-homebrew, brew, homebrew-core, homebrew-cask, ... }: {
    darwinConfigurations.macbook = {
      # (...)
      modules = [
        {
          nix-homebrew = {
            # Install Homebrew under the default prefix
            enable = true;

            # Apple Silicon Only: Also install Homebrew under the default Intel prefix for Rosetta 2
            enableRosetta = true;

            # User owning the Homebrew prefix
            user = "yourname";

            # Optional: Declarative tap management
            taps = {
              "homebrew/homebrew-core" = homebrew-core;
              "homebrew/homebrew-cask" = homebrew-cask;
            };

            # Optional: Enable fully-declarative tap management
            #
            # With mutableTaps disabled, taps can no longer be added imperatively with `brew tap`.
            mutableTaps = false;
          };
        }
      ];
    };
  };
}
```

Once activated, a unified `brew` launcher will be created under `/run/current-system/sw/bin` that automatically selects the correct Homebrew prefix to use based on the architecture.
Run `arch -x86_64 brew` to install X86-64 packages through Rosetta 2.

It's also possible to migrate an existing installation of Homebrew to be managed by `nix-homebrew` (experimental).
You will receive instructions on how to perform the migration during activation.

With `nix-homebrew.mutableTaps = false`, taps can be removed by deleting the corresponding attribute in `nix-homebrew.taps` and activating the new configuration.

## Non-Standard Prefixes

Extra prefixes may be configured:

```nix
{
  nix-homebrew.prefixes = {
    "/some/prefix" = {
      library = "/some/prefix/Library";
      taps = {
        # ...
      };
    };
  };
}
```

Note that with a non-standard prefix, you will no longer be able to use most bottles (prebuilt packages).