flake: parametrize host — one entry per machine

mkDarwinHost carries the shared modules; a new Mac is one line in
darwinConfigurations (plus optional per-host extraModules). NIX_HOST in
the Makefile and bootstrap.sh comes from scutil now, and the CI eval
covers every declared host automatically instead of naming one.

Author: sanketsudake

.github/workflows/checks.yml

@@ -45,7 +45,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: DeterminateSystems/nix-installer-action@v16
       - run: nix flake check
-      # Pure eval type-checks the whole darwin + home-manager module tree;
-      # no macOS runner needed.
-      - run: nix eval .#darwinConfigurations.Sankets-MacBook-Air.system.drvPath
+      # Pure eval type-checks every host's darwin + home-manager module tree;
+      # no macOS runner needed, and new hosts are covered automatically.
+      - run: nix eval .#darwinConfigurations --apply 'cfgs: builtins.mapAttrs (_: c: c.system.drvPath) cfgs'
       - run: nix run nixpkgs#statix -- check nix/

Makefile

@@ -13,7 +13,9 @@ HM_PACKAGES := zsh git atuin btop gh bin
 
 # The brewfile is generated by the nix-darwin homebrew module
 # (nix/darwin/homebrew.nix); scripts/nix-brewfile.sh prints its path.
-NIX_HOST := Sankets-MacBook-Air
+# The local host name selects the darwinConfigurations entry; a new machine
+# needs its own entry in flake.nix (see mkDarwinHost).
+NIX_HOST := $(shell scutil --get LocalHostName)
 # Absolute paths: make's shell (and sudo's secure_path) don't carry the
 # nix profile dirs.
 NIX := /nix/var/nix/profiles/default/bin/nix

bootstrap.sh

@@ -7,15 +7,14 @@
 #   curl -fsSL https://raw.githubusercontent.com/sanketsudake/dotfiles/main/bootstrap.sh -o /tmp/bootstrap.sh
 #   bash /tmp/bootstrap.sh
 #
-# The flake pins one host config (see NIX_HOST in the Makefile). On a machine
-# with a different LocalHostName, add a darwinConfigurations entry for it (or
-# rename the machine) before bootstrapping.
+# The host name selects the darwinConfigurations entry; on a new machine, add
+# an entry for its LocalHostName in flake.nix (mkDarwinHost) before running.
 set -euo pipefail
 
 DOTFILES_DIR="${DOTFILES_DIR:-$HOME/personal/dotfiles}"
 DOTFILES_SSH="git@github.com:sanketsudake/dotfiles.git"
 DOTFILES_HTTPS="https://github.com/sanketsudake/dotfiles.git"
-NIX_HOST="Sankets-MacBook-Air"
+NIX_HOST="$(scutil --get LocalHostName)"
 
 step() { printf '\n==> %s\n' "$*"; }
 

flake.nix

@@ -15,22 +15,30 @@
 
   outputs =
     inputs@{ nixpkgs, nix-darwin, ... }:
+    let
+      # One host = one entry below. Shared config lives in nix/darwin and
+      # nix/home; per-host overrides go in the extraModules list.
+      mkDarwinHost =
+        extraModules:
+        nix-darwin.lib.darwinSystem {
+          specialArgs = { inherit inputs; };
+          modules = [
+            ./nix/darwin
+            inputs.home-manager.darwinModules.home-manager
+            {
+              home-manager = {
+                useGlobalPkgs = true;
+                useUserPackages = true;
+                backupFileExtension = "hm-backup";
+                users.sanketsudake = import ./nix/home;
+              };
+            }
+          ]
+          ++ extraModules;
+        };
+    in
     {
-      darwinConfigurations."Sankets-MacBook-Air" = nix-darwin.lib.darwinSystem {
-        specialArgs = { inherit inputs; };
-        modules = [
-          ./nix/darwin
-          inputs.home-manager.darwinModules.home-manager
-          {
-            home-manager = {
-              useGlobalPkgs = true;
-              useUserPackages = true;
-              backupFileExtension = "hm-backup";
-              users.sanketsudake = import ./nix/home;
-            };
-          }
-        ];
-      };
+      darwinConfigurations."Sankets-MacBook-Air" = mkDarwinHost [ ];
 
       formatter.aarch64-darwin = nixpkgs.legacyPackages.aarch64-darwin.nixfmt-rfc-style;
     };