feat: use flake-parts and auto-generate nixosConfigurations for all hosts

flake.lock

@@ -1,5 +1,23 @@
 {
   "nodes": {
+    "flake-parts": {
+      "inputs": {
+        "nixpkgs-lib": "nixpkgs-lib"
+      },
+      "locked": {
+        "lastModified": 1743550720,
+        "narHash": "sha256-hIshGgKZCgWh6AYJpJmRgFdR3WUbkY04o82X05xqQiY=",
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "rev": "c621e8422220273271f52058f618c94e405bb0f5",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "type": "github"
+      }
+    },
     "nixos-hardware": {
       "locked": {
         "lastModified": 1743420942,
@@ -32,8 +50,24 @@
         "type": "github"
       }
     },
+    "nixpkgs-lib": {
+      "locked": {
+        "lastModified": 1743296961,
+        "narHash": "sha256-b1EdN3cULCqtorQ4QeWgLMrd5ZGOjLSLemfa00heasc=",
+        "owner": "nix-community",
+        "repo": "nixpkgs.lib",
+        "rev": "e4822aea2a6d1cdd36653c134cacfd64c97ff4fa",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "nixpkgs.lib",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
+        "flake-parts": "flake-parts",
         "nixos-hardware": "nixos-hardware",
         "nixpkgs": "nixpkgs"
       }

flake.nix

@@ -2,16 +2,16 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.11";
     nixos-hardware.url = "github:NixOS/nixos-hardware/master";
+    flake-parts.url = "github:hercules-ci/flake-parts";
   };
 
-  outputs = inputs @ { self, nixpkgs, ... }: {
-    nixosConfigurations.backstage = nixpkgs.lib.nixosSystem {
-      system = "x86_64-linux";
-      modules = [
-        ./hosts/backstage
-      ];
-      specialArgs = { inherit inputs; };
-    };
+  outputs = inputs: inputs.flake-parts.lib.mkFlake { inherit inputs; }  {
+    systems = [
+      "x86_64-linux"
+    ];
+    imports = [
+      ./hosts
+    ];
   };
 }
 

hosts/default.nix

@@ -0,0 +1,20 @@
+{inputs, self, ...}:
+let
+  inherit (inputs.nixpkgs) lib;
+  isDirectory = _name: type: type == "directory";
+  hostNames = builtins.attrNames (
+    lib.filterAttrs isDirectory (builtins.readDir ./.)
+  );
+  hosts = lib.genAttrs hostNames (name: {
+    modules = [
+      (./. + "/${name}")
+    ];
+  });
+in 
+{
+  flake.nixosConfigurations = lib.mapAttrs (host: hostConfig: lib.nixosSystem {
+    inherit (hostConfig) modules;
+    system = "x86_64-linux";
+    specialArgs = { inherit inputs; };
+  }) hosts;
+}