feat(configurations)!: flatten down, introduce meta.nix

Flatten down directory structure:
- From: `./hosts/${configuration-type}/${system}/{configuration,deploy}.nix`
-   To: `./hosts/${configuration-type}/{meta,configuration}.nix`
Keep `system` and `deploy-rs` config in `meta.nix`
Update `flake.lock`

flake.lock

@@ -14,11 +14,11 @@
         "systems": "systems"
       },
       "locked": {
-        "lastModified": 1722339003,
+        "lastModified": 1723293904,
-        "narHash": "sha256-ZeS51uJI30ehNkcZ4uKqT4ZDARPyqrHADSKAwv5vVCU=",
+        "narHash": "sha256-b+uqzj+Wa6xgMS9aNbX4I+sXeb5biPDi39VgvSFqFvU=",
         "owner": "ryantm",
         "repo": "agenix",
-        "rev": "3f1dae074a12feb7327b4bf43cbac0d124488bb7",
+        "rev": "f6291c5935fdc4e0bef208cfc0dcab7e3f7a1c41",
         "type": "github"
       },
       "original": {
@@ -37,11 +37,11 @@
         "pre-commit-hooks": "pre-commit-hooks"
       },
       "locked": {
-        "lastModified": 1722299223,
+        "lastModified": 1722597419,
-        "narHash": "sha256-+5HNJBXb9YXKSmi2TJsnftrgU/msF/4jBAMH9J1bc5c=",
+        "narHash": "sha256-YbMzll0Dh2ln/TryDP+S3IGm8nRHkzcSQIubI4ZEOAw=",
         "owner": "oddlama",
         "repo": "agenix-rekey",
-        "rev": "4107b53b152f4ddc504269ec17c4b7005869d762",
+        "rev": "126b4a5133eb361cbf5bf90e44c71b6f830845ec",
         "type": "github"
       },
       "original": {
@@ -175,11 +175,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1722476845,
+        "lastModified": 1723426710,
-        "narHash": "sha256-7gZ8uf3qOox8Vrwd+p9EhUHHLhhK8lis/5KcXGmIaow=",
+        "narHash": "sha256-yrS9al6l3fYfFfvovnyBWnyELDQOdfKyai4K/jKgoBw=",
         "owner": "nix-community",
         "repo": "disko",
-        "rev": "7e1b215a0a96efb306ad6440bf706d2b307dc267",
+        "rev": "0d510fe40b56ed74907a021d7e1ffd0042592914",
         "type": "github"
       },
       "original": {
@@ -367,11 +367,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1719994518,
+        "lastModified": 1722555600,
-        "narHash": "sha256-pQMhCCHyQGRzdfAkdJ4cIWiw+JNuWsTX7f0ZYSyz0VY=",
+        "narHash": "sha256-XOQkdLafnb/p9ij77byFQjDf5m5QYl9b2REiVClC+x4=",
         "owner": "hercules-ci",
         "repo": "flake-parts",
-        "rev": "9227223f6d922fee3c7b190b2cc238a99527bbb7",
+        "rev": "8471fe90ad337a8074e957b69ca4d0089218391d",
         "type": "github"
       },
       "original": {
@@ -576,11 +576,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1721042469,
+        "lastModified": 1723202784,
-        "narHash": "sha256-6FPUl7HVtvRHCCBQne7Ylp4p+dpP3P/OYuzjztZ4s70=",
+        "narHash": "sha256-qbhjc/NEGaDbyy0ucycubq4N3//gDFFH3DOmp1D3u1Q=",
         "owner": "cachix",
         "repo": "git-hooks.nix",
-        "rev": "f451c19376071a90d8c58ab1a953c6e9840527fd",
+        "rev": "c7012d0c18567c889b948781bc74a501e92275d1",
         "type": "github"
       },
       "original": {
@@ -678,11 +678,11 @@
     },
     "hardware": {
       "locked": {
-        "lastModified": 1722332872,
+        "lastModified": 1723310128,
-        "narHash": "sha256-2xLM4sc5QBfi0U/AANJAW21Bj4ZX479MHPMPkB+eKBU=",
+        "narHash": "sha256-IiH8jG6PpR4h9TxSGMYh+2/gQiJW9MwehFvheSb5rPc=",
         "owner": "nixos",
         "repo": "nixos-hardware",
-        "rev": "14c333162ba53c02853add87a0000cbd7aa230c2",
+        "rev": "c54cf53e022b0b3c1d3b8207aa0f9b194c24f0cf",
         "type": "github"
       },
       "original": {
@@ -720,11 +720,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1722462338,
+        "lastModified": 1723399884,
-        "narHash": "sha256-ss0G8t8RJVDewA3MyqgAlV951cWRK6EtVhVKEZ7J5LU=",
+        "narHash": "sha256-97wn0ihhGqfMb8WcUgzzkM/TuAxce2Gd20A8oiruju4=",
         "owner": "nix-community",
         "repo": "home-manager",
-        "rev": "6e090576c4824b16e8759ebca3958c5b09659ee8",
+        "rev": "086f619dd991a4d355c07837448244029fc2d9ab",
         "type": "github"
       },
       "original": {
@@ -756,11 +756,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1722491724,
+        "lastModified": 1723367191,
-        "narHash": "sha256-pvZ0sqDNhcUzYXrCF9UYZBf+qd3ri/0fT0b4mFqVuBs=",
+        "narHash": "sha256-noi5tre7BLtxImN38jEHeVOtOG1Xu37sJFwHKSAPHjo=",
         "owner": "Jovian-Experiments",
         "repo": "Jovian-NixOS",
-        "rev": "ff83ee27a56651dcd6d4c9b3e3b7c08267dc52ae",
+        "rev": "91178062f365b64eece94c5dff93e09b07e87d9d",
         "type": "github"
       },
       "original": {
@@ -827,11 +827,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1722471252,
+        "lastModified": 1723528508,
-        "narHash": "sha256-rgNPBiWN+y2jBiXIEgV/McBfkPeZax80eol0FBoupCk=",
+        "narHash": "sha256-4++qlOlqMoZz3h/g48f+TY3r75h+EBToRNmgcVWKpsE=",
         "owner": "nix-community",
         "repo": "neovim-nightly-overlay",
-        "rev": "fe7178b41d84add25c63a695620629050fb35bbd",
+        "rev": "f019c7b0e7f478e4aaf2b406785a8d6ec6d1957d",
         "type": "github"
       },
       "original": {
@@ -843,11 +843,11 @@
     "neovim-src": {
       "flake": false,
       "locked": {
-        "lastModified": 1722463651,
+        "lastModified": 1723504195,
-        "narHash": "sha256-3YorBqxT1RpL3Z2rLDCJhG+1HnBsgjrW8AOlTkFWlbA=",
+        "narHash": "sha256-Tt+UtP3iSQATu2CUgFgtPkobASE7Rbf2AWZeLH8fthU=",
         "owner": "neovim",
         "repo": "neovim",
-        "rev": "e820474cde09273608be5f57e1032aab21e3c97d",
+        "rev": "9768e88f3891b5594eb2d556bd3bdf40c61d46e1",
         "type": "github"
       },
       "original": {
@@ -882,11 +882,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1722500642,
+        "lastModified": 1722924007,
-        "narHash": "sha256-Vls0TQRdplex1JslnBxEk3M26Q1vR+OSg+sk5rBG4DA=",
+        "narHash": "sha256-+CQDamNwqO33REJLft8c26NbUi2Td083hq6SvAm2xkU=",
         "owner": "lnl7",
         "repo": "nix-darwin",
-        "rev": "b47af8628624856ad6853168298f1f96364d92d6",
+        "rev": "91010a5613ffd7ee23ee9263213157a1c422b705",
         "type": "github"
       },
       "original": {
@@ -1123,11 +1123,11 @@
     },
     "nixpkgs_2": {
       "locked": {
-        "lastModified": 1722421184,
+        "lastModified": 1723362943,
-        "narHash": "sha256-/DJBI6trCeVnasdjUo9pbnodCLZcFqnVZiLUfqLH4jA=",
+        "narHash": "sha256-dFZRVSgmJkyM0bkPpaYRtG/kRMRTorUIDj8BxoOt1T4=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "9f918d616c5321ad374ae6cb5ea89c9e04bf3e58",
+        "rev": "a58bc8ad779655e790115244571758e8de055e3d",
         "type": "github"
       },
       "original": {
@@ -1225,11 +1225,11 @@
     },
     "nur": {
       "locked": {
-        "lastModified": 1722577920,
+        "lastModified": 1723549487,
-        "narHash": "sha256-+Nilyq9pr3f13pNqE3UaJ/zxB69fQ8MmkA5xu6oYtIs=",
+        "narHash": "sha256-65NYBcYUx0DjL7TGlesle5PdtJVfOCPnv5zvsgB/dRw=",
         "owner": "nix-community",
         "repo": "NUR",
-        "rev": "a3f8a8853ee2e17c2efd5a33a5c91c1d79bc9c49",
+        "rev": "20b1fc4032363116a880dc64e3fa96f8a24d4e64",
         "type": "github"
       },
       "original": {
@@ -1701,11 +1701,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1722558337,
+        "lastModified": 1723551051,
-        "narHash": "sha256-001MFcaVzqfl/d+dhAz4FTWHlHCYU/7nZ9OVWiYLkeI=",
+        "narHash": "sha256-+H7sSt93MLs82ZVdhuHlUPfUL+anMvR3+UrVyZTIxjo=",
         "owner": "mitchellh",
         "repo": "zig-overlay",
-        "rev": "93eec9c6ff998133fdeed5eb96c4c59fc2b66b7c",
+        "rev": "2a8a3228bca531f3c4482268f7262dacf372baf6",
         "type": "github"
       },
       "original": {
@@ -1727,11 +1727,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1722209386,
+        "lastModified": 1723396350,
-        "narHash": "sha256-GAzXTJUJJIXrAlHkInSDwlnVQPL5BV1Enbj3R4ipGFk=",
+        "narHash": "sha256-f5RTadUCYeGPDI6Y7xDYa6sJsdKFCdtD4WipGxuof3A=",
         "owner": "zigtools",
         "repo": "zls",
-        "rev": "eba1489b6ffa6db7f0eaefce6e06d53cd9066f7b",
+        "rev": "3ec8ad16337e5fc391fbdfb394f68f155b2a7a69",
         "type": "github"
       },
       "original": {

flake.nix

@@ -17,7 +17,6 @@
         ./modules/flake/modules
         ./modules/flake/configurations
         ./modules/flake/agenix
-        ./modules/flake/deploy
         ./modules/flake/topology
         ./modules/flake/packages
         ./modules/flake/overlays
@@ -35,19 +34,19 @@
       flake = {
         inherit (inputs) self;
 
-        # Automatic modules, see `./modules/flake/modules.nix`
+        # Automatic modules, see `./modules/flake/modules/default.nix`
         autoModules.enableAll = true;
 
-        # Automatic configurations, see `./modules/flake/configurations.nix`
+        # Automatic configurations, see `./modules/flake/configurations/default.nix`
         autoConfigurations.enableAll = true;
 
-        # Automatic packages, see `./modules/flake/packages/default.nix`
+        # Automatic packages, see `./modules/flake/packages/default/default.nix`
         autoPackages.enable = true;
 
-        # Automatic overlays, see `./modules/flake/overlays/default.nix`
+        # Automatic overlays, see `./modules/flake/overlays/default/default.nix`
         autoOverlays.enable = true;
 
-        # Automatic devShells, see `./modules/flake/shells/default.nix`
+        # Automatic devShells, see `./modules/flake/shells/default/default.nix`
         autoDevShells.enable = true;
 
         # Templates

hosts/home-manager/__template__/meta.nix

@@ -0,0 +1,3 @@
+{
+  system = "x86_64-linux";
+}

hosts/nix-darwin/apavel-a01/home/apavel.nix

@@ -20,7 +20,7 @@
 
     # Zig
     zigpkgs.master
-    inputs.zls-overlay.packages.x86_64-darwin.default
+    # inputs.zls-overlay.packages.x86_64-darwin.default
   ];
 
   programs.git = {

hosts/nix-darwin/apavel-a01/meta.nix

@@ -0,0 +1,3 @@
+{
+  system = "x86_64-darwin";
+}

hosts/nix-darwin/limonka/home/pavelatanasov.nix

@@ -66,7 +66,7 @@
     nurl
 
     # Mail
-    # himalaya
+    himalaya
 
     # Java
     graalvm-ce
@@ -87,7 +87,7 @@
 
     # Zig
     zigpkgs.master
-    inputs.zls-overlay.packages.${pkgs.system}.default
+    # inputs.zls-overlay.packages.${pkgs.system}.default
 
     # Android
     android-tools

hosts/nix-darwin/limonka/meta.nix

@@ -0,0 +1,15 @@
+{
+  system = "aarch64-darwin";
+  deploy = {
+    hostname = "localhost";
+    sshUser = "pavelatanasov";
+    user = "pavelatanasov";
+    sudo = "sudo -u";
+    sshOpts = [ ];
+    fastConnection = false;
+    autoRollback = true;
+    magicRollback = true;
+    tempPath = "/Users/pavelatanasov/.deploy-rs";
+    remoteBuild = true;
+  };
+}

hosts/nix-darwin/limontozu/meta.nix

@@ -0,0 +1,3 @@
+{
+  system = "x86_64-darwin";
+}

hosts/nix-on-droid/cheetah/meta.nix

@@ -0,0 +1,3 @@
+{
+  system = "aarch64-linux";
+}

hosts/nixos/__template__/meta.nix

@@ -0,0 +1,3 @@
+{
+  system = "x86_64-linux";
+}

hosts/nixos/homix/meta.nix

@@ -0,0 +1,3 @@
+{
+  system = "x86_64-linux";
+}

hosts/nixos/jeeves/configuration.nix

@@ -23,6 +23,7 @@
   # services.kanidm = { };
 
   age.rekey = {
+    # TODO: store in `meta`
     hostPubkey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIPopSTZ81UyKp9JSljCLp+Syk51zacjh9fLteqxQ6/aB";
     # masterIdentities = [ "${inputs.self}/secrets/privkey.age" ];
     # storageMode = "local";
@@ -74,7 +75,10 @@
 
   environment.systemPackages = with pkgs; [
     git
-    neovim
+    # FIXME: cannot deploy neovim-nightly
+    #                               V neovim source
+    #      > error: cannot add path '/nix/store/rhjznh5jdzdkzbnn0fhhvcf9rys0s59d-source' because it lacks a signature by a trusted key
+    # neovim
   ];
 
   # NOTE: made with `mkpasswd -m sha-512`

hosts/nixos/jeeves/home/jeeves.nix

@@ -16,7 +16,7 @@
 
   home.packages = with pkgs; [
     ## Core
-    neovim
+    # neovim
     git
     gnupg
     pciutils # lspci

hosts/nixos/jeeves/meta.nix

@@ -0,0 +1,48 @@
+{
+  # The `system` of the host
+  system = "x86_64-linux";
+
+  # `deploy-rs` configuration
+  deploy = {
+    # This is the hostname by which you'll refer to this machine using reploy-rs
+    hostname = "jeeves.reo101.xyz";
+
+    # This is the user that deploy-rs will use when connecting.
+    # This will default to your own username if not specified anywhere
+    sshUser = "jeeves";
+
+    # This is the user that the profile will be deployed to (will use sudo if not the same as above).
+    # If `sshUser` is specified, this will be the default (though it will _not_ default to your own username)
+    user = "root";
+
+    # Which sudo command to use. Must accept at least two arguments:
+    # the user name to execute commands as and the rest is the command to execute
+    # This will default to "sudo -u" if not specified anywhere.
+    sudo = "sudo -u";
+
+    # This is an optional list of arguments that will be passed to SSH.
+    sshOpts = [ "-p" "727" ];
+
+    # Fast connection to the node. If this is true, copy the whole closure instead of letting the node substitute.
+    # This defaults to `false`
+    fastConnection = false;
+
+    # If the previous profile should be re-activated if activation fails.
+    # This defaults to `true`
+    autoRollback = true;
+
+    # See the earlier section about Magic Rollback for more information.
+    # This defaults to `true`
+    magicRollback = true;
+
+    # The path which deploy-rs will use for temporary files, this is currently only used by `magicRollback` to create an inotify watcher in for confirmations
+    # If not specified, this will default to `/tmp`
+    # (if `magicRollback` is in use, this _must_ be writable by `user`)
+    tempPath = "/tmp";
+
+    # Build the derivation on the target system
+    # Will also fetch all external dependencies from the target system's substituters.
+    # This default to `false`
+    remoteBuild = true;
+  };
+}

hosts/nixos/x86_64-linux/jeeves/deploy.nix

@@ -1,42 +0,0 @@
-{
-  # This is the hostname by which you'll refer to this machine using reploy-rs
-  hostname = "jeeves.reo101.xyz";
-
-  # This is the user that deploy-rs will use when connecting.
-  # This will default to your own username if not specified anywhere
-  sshUser = "jeeves";
-
-  # This is the user that the profile will be deployed to (will use sudo if not the same as above).
-  # If `sshUser` is specified, this will be the default (though it will _not_ default to your own username)
-  user = "root";
-
-  # Which sudo command to use. Must accept at least two arguments:
-  # the user name to execute commands as and the rest is the command to execute
-  # This will default to "sudo -u" if not specified anywhere.
-  sudo = "sudo -u";
-
-  # This is an optional list of arguments that will be passed to SSH.
-  sshOpts = [ "-p" "727" ];
-
-  # Fast connection to the node. If this is true, copy the whole closure instead of letting the node substitute.
-  # This defaults to `false`
-  fastConnection = false;
-
-  # If the previous profile should be re-activated if activation fails.
-  # This defaults to `true`
-  autoRollback = true;
-
-  # See the earlier section about Magic Rollback for more information.
-  # This defaults to `true`
-  magicRollback = true;
-
-  # The path which deploy-rs will use for temporary files, this is currently only used by `magicRollback` to create an inotify watcher in for confirmations
-  # If not specified, this will default to `/tmp`
-  # (if `magicRollback` is in use, this _must_ be writable by `user`)
-  tempPath = "/tmp";
-
-  # Build the derivation on the target system
-  # Will also fetch all external dependencies from the target system's substituters.
-  # This default to `false`
-  remoteBuild = true;
-}

modules/flake/configurations/default.nix

@@ -6,11 +6,12 @@ let
     hasFiles
     hasDirectories
     recurseDir
-    configuration-type-to-outputs-modules;
+    kebabToCamel
+    configuration-type-to-outputs-modules
+    configuration-type-to-outputs-configurations;
 in
 let
   # Configuration helpers
-  configurationTypes = ["nixos" "nix-on-droid" "nix-darwin" "home-manager"];
 
   # `pkgs` with flake's overlays
   # NOTE: done here to avoid infinite recursion
@@ -18,7 +19,15 @@ let
     (withSystem system ({ pkgs, ... }: pkgs)).extend
       (final: prev: inputs.self.packages.${system});
 
-  homeManagerModule = { root, system, hostname, users ? null }: {
+  genUsers = configurationFiles:
+    lib.pipe configurationFiles [
+      (cf: cf."home" or { })
+      builtins.attrNames
+      (builtins.map
+        (lib.strings.removeSuffix ".nix"))
+    ];
+
+  homeManagerModule = { root, meta, users ? null }: {
     home-manager = {
       # Use same `pkgs` instance as system (i.e. carry over overlays)
       useGlobalPkgs = true;
@@ -26,11 +35,10 @@ let
       useUserPackages = true;
       # Default import all of our exported `home-manager` modules
       sharedModules = builtins.attrValues config.flake.${configuration-type-to-outputs-modules "home-manager"};
-      # Pass in `inputs`, `outputs` and maybe `meta`
+      # Pass in `inputs`, `hostname` and `meta`
       extraSpecialArgs = {
         inherit inputs;
-        # TODO: meta?
+        inherit meta;
-        inherit hostname;
       };
     } // (if users == null then {
       # nixOnDroid
@@ -44,9 +52,9 @@ let
     });
   };
 
-  mkNixosHost = args @ { root, system, hostname, users }: inputs.nixpkgs.lib.nixosSystem {
+  mkNixosHost = args @ { root, meta, users }: inputs.nixpkgs.lib.nixosSystem {
-    inherit system;
+    inherit (meta) system;
-    pkgs = pkgs' system;
+    pkgs = pkgs' meta.system;
 
     modules = [
       # Main configuration
@@ -61,19 +69,21 @@ let
       inputs.nix-topology.nixosModules.default
       # Sane default `networking.hostName`
       {
-        networking.hostName = lib.mkDefault hostname;
+        networking.hostName = lib.mkDefault meta.hostname;
       }
+         # TODO: lib.optionals
     ] ++ (builtins.attrValues config.flake.${configuration-type-to-outputs-modules "nixos"});
 
     specialArgs = {
       inherit inputs;
+      inherit meta;
     };
   };
 
-  mkNixOnDroidHost = args @ { root, system, hostname }: inputs.nix-on-droid.lib.nixOnDroidConfiguration {
+  mkNixOnDroidHost = args @ { root, meta }: inputs.nix-on-droid.lib.nixOnDroidConfiguration {
     # NOTE: inferred by `pkgs.system`
     # inherit system;
-    pkgs = pkgs' system;
+    pkgs = pkgs' meta.system;
 
     modules = [
       # Main configuration
@@ -84,14 +94,15 @@ let
 
     extraSpecialArgs = {
       inherit inputs;
+      inherit meta;
     };
 
     home-manager-path = inputs.home-manager.outPath;
   };
 
-  mkNixDarwinHost = args @ { root, system, hostname, users }: inputs.nix-darwin.lib.darwinSystem {
+  mkNixDarwinHost = args @ { root, meta, users }: inputs.nix-darwin.lib.darwinSystem {
-    inherit system;
+    inherit (meta) system;
-    pkgs = pkgs' system;
+    pkgs = pkgs' meta.system;
 
     modules = [
       # Main configuration
@@ -107,12 +118,13 @@ let
 
     specialArgs = {
       inherit inputs;
+      inherit meta;
     };
   };
 
-  mkHomeManagerHost = args @ { root, system, hostname }: inputs.home-manager.lib.homeManagerConfiguration {
+  mkHomeManagerHost = args @ { root, meta }: inputs.home-manager.lib.homeManagerConfiguration {
-    inherit system;
+    inherit (meta) system;
-    pkgs = pkgs' system;
+    pkgs = pkgs' meta.system;
 
     modules = [
       "${root}/home.nix"
@@ -120,30 +132,9 @@ let
 
     extraSpecialArgs = {
       inherit inputs;
-      inherit hostname;
+      inherit meta;
     };
   };
-
-  createConfigurations =
-    pred: mkHost: hosts:
-    lib.foldAttrs
-      lib.const
-      [ ]
-      (builtins.attrValues
-        (builtins.mapAttrs
-          (system: hosts:
-            lib.concatMapAttrs
-              (host: configurationFiles:
-                lib.optionalAttrs
-                  (and [
-                    (host != "__template__")
-                    (pred { inherit system host configurationFiles; })
-                  ])
-                  {
-                    ${host} = mkHost { inherit system host configurationFiles; };
-                  })
-              hosts)
-          hosts));
 in
 {
   options = let
@@ -153,9 +144,18 @@ in
       description = ''
         Automagically generate configurations from walking directories with Nix files
       '';
-      type = types.submodule (submodule: {
+      internal = true;
+      type = types.submodule (autoConfigurationsSubmodule: let
+        inherit (autoConfigurationsSubmodule.config)
+          configurationTypes
+          enableAll
+          baseDir
+          ;
+      in {
         options = {
-          enableAll = lib.mkEnableOption "Automatic ${builtins.toString configurationTypes} configurations extraction";
+          enableAll = lib.mkEnableOption ''
+            Automatic ${builtins.toString (lib.attrValues configurationTypes)} configurations extraction
+          '';
           baseDir = lib.mkOption {
             description = ''
               Base directory of the contained configurations, used as a base for the rest of the options
@@ -164,135 +164,291 @@ in
             default = "${self}/hosts";
             defaultText = ''''${self}/hosts'';
           };
-        } // (
+          configurationTypes = lib.mkOption {
-          lib.pipe
+            type = types.attrsOf (types.submodule (configurationTypeSubmodule@{ name, ... }: let
-          configurationTypes
+              inherit (configurationTypeSubmodule.config)
-          [
+                # enable
-            (builtins.map
+                dir
-              # NOTE: create small submodule for every `configurationType`
+                predicate
-              (configurationType:
+                mkHost
-                lib.nameValuePair
+                mkDeployNode
-                "${configurationType}"
+                ;
-                (lib.mkOption {
+            in {
-                  type = types.submodule {
               options = {
-                      # NOTE: each can be enabled (default global `enableAll`)
+                enable = lib.mkEnableOption "Automatic ${name} configurations extraction" // {
-                      enable = lib.mkEnableOption "Automatic ${configurationType} configurations extraction" // {
+                  default = enableAll;
-                        default = submodule.config.enableAll;
                 };
                 # NOTE: each can be read from a different directory
-                      # (default global `baseDir` + `camelToKebab`-ed `configurationType`)
                 dir = lib.mkOption {
                   type = types.path;
-                        default = "${submodule.config.baseDir}/${configurationType}";
+                  default = "${baseDir}/${name}";
                 };
-                      # TODO: split hosts and configurations?
+                hostsName = lib.mkOption {
-                      resultHosts = lib.mkOption {
                   description = ''
-                          The resulting automatic packages
+                    Name of the `hosts` output
                   '';
-                        # TODO: specify
+                  type = types.str;
+                  default = "${kebabToCamel name}Hosts";
+                };
+                configurationsName = lib.mkOption {
+                  description = ''
+                    Name of the `configurations` output
+                  '';
+                  type = types.str;
+                  default = "${kebabToCamel name}Configurations";
+                };
+                predicate = lib.mkOption {
+                  description = ''
+                    Function for filtering configurations
+                  '';
+                  # FIXME: `merge` of `functionTo` type causes a stray `passthru` to attempt getting evaluated
+                  # type = types.functionTo types.anything;
                   type = types.unspecified;
-                        readOnly = true;
+                  example = /* nix */ ''
-                        internal = true;
+                    { root, host, configurationFiles, ... }:
-                        default =
+                      # Utils from `./modules/flake/lib/default.nix`
-                          lib.optionalAttrs
+                      and [
-                            config.flake.autoConfigurations.${configurationType}.enable
+                        (! (host == "__template__"))
-                            (recurseDir config.flake.autoConfigurations.${configurationType}.dir);
-                      };
-                    };
-                  };
-                  default = {};
-                })))
-            builtins.listToAttrs
-          ]);
-      });
-      default = {};
-    };
-  };
-
-  config = {
-    flake = {
-      # Configurations
-      nixosConfigurations =
-        createConfigurations
-          ({ system, host, configurationFiles, ... }:
-            and
-              [
-                (hasFiles
-                  [ "configuration.nix" ]
-                  configurationFiles)
-                # (hasDirectories
-                #   [ "home" ]
-                #   config)
-              ])
-          ({ system, host, configurationFiles, ... }:
-            mkNixosHost {
-              root = "${config.flake.autoConfigurations.nixos.dir}/${system}/${host}";
-              inherit system;
-              hostname = host;
-              users = (builtins.map
-                (lib.strings.removeSuffix ".nix")
-                (builtins.attrNames (configurationFiles."home" or { })));
-            })
-          config.flake.autoConfigurations.nixos.resultHosts;
-
-      nixOnDroidConfigurations =
-        createConfigurations
-          ({ system, host, configurationFiles, ... }:
-            and
-              [
-                (hasFiles
-                  [ "configuration.nix" "home.nix" ]
-                  configurationFiles)
-              ])
-          ({ system, host, configurationFiles, ... }:
-            mkNixOnDroidHost {
-              root = "${config.flake.autoConfigurations.nix-on-droid.dir}/${system}/${host}";
-              inherit system;
-              hostname = host;
-            })
-          config.flake.autoConfigurations.nix-on-droid.resultHosts;
-
-      darwinConfigurations =
-        createConfigurations
-          ({ system, host, configurationFiles, ... }:
-            and
-              [
                         (hasFiles
                           [ "configuration.nix" ]
                           configurationFiles)
                         (hasDirectories
                           [ "home" ]
                           configurationFiles)
-              ])
+                      ]
-          ({ system, host, configurationFiles, ... }:
+                  '';
-            mkNixDarwinHost {
-              root = "${config.flake.autoConfigurations.nix-darwin.dir}/${system}/${host}";
-              inherit system;
-              hostname = host;
-              users = (builtins.map
-                (lib.strings.removeSuffix ".nix")
-                (builtins.attrNames (configurationFiles."home" or { })));
-            })
-          config.flake.autoConfigurations.nix-darwin.resultHosts;
-
-      homeConfigurations =
-        createConfigurations
-          ({ system, host, configurationFiles, ... }:
-            and
-              [
-                (hasFiles
-                  [ "home.nix" ]
-                  configurationFiles)
-              ])
-          ({ system, host, configurationFiles, ... }:
-            mkHomeManagerHost {
-              root = "${config.flake.autoConfigurations.home-manager.dir}/${system}/${host}";
-              inherit system;
-              hostname = host;
-            })
-          config.flake.autoConfigurations.home-manager.resultHosts;
                 };
+                mkHost = lib.mkOption {
+                  description = ''
+                    Function for generating a configuration
+                  '';
+                  # type = types.functionTo types.anything;
+                  type = types.unspecified;
+                  example = /* nix */ ''
+                    args @ { root, meta, users }: inputs.nixpkgs.lib.nixosSystem {
+                      inherit (meta) system;
+
+                      modules = [
+                        # Main configuration
+                        "''${root}/configuration.nix"
+                        # Home Manager
+                        inputs.home-manager.nixosModules.home-manager
+                        (homeManagerModule args)
+                      ] ++ (builtins.attrValues config.flake.''${configuration-type-to-outputs-modules "nixos"});
+
+                      specialArgs = {
+                        inherit inputs;
+                        inherit meta;
+                      };
+                    };
+                  '';
+                };
+                mkDeployNode = lib.mkOption {
+                  description = ''
+                    Function for generating a `deploy-rs` node (null to skip)
+                  '';
+                  type = types.nullOr (types.functionTo types.anything);
+                  default = null;
+                  # TODO: update
+                  example = /* nix */ ''
+                    args @ { root, host, meta, configuration }:
+                      inputs.deploy-rs.''${meta.system}.activate.nixos configuration;
+                  '';
+                };
+                resultConfigurations = lib.mkOption {
+                  description = ''
+                    The resulting automatic configurations
+                  '';
+                  # TODO: specify
+                  type = types.unspecified;
+                  readOnly = true;
+                  default =
+                    lib.pipe dir [
+                      recurseDir
+                      (lib.concatMapAttrs
+                        (host: configurationFiles:
+                          let
+                            root = "${dir}/${host}";
+                            meta-path = "${root}/meta.nix";
+                            meta = import meta-path;
+                            deploy-config = meta.deploy or null;
+                            has-mkDeployNode = mkDeployNode != null;
+                            has-deploy-config = builtins.pathExists meta-path && deploy-config != null;
+                            configuration-args = { inherit root host configurationFiles; };
+                            valid = predicate configuration-args;
+                            configuration = mkHost configuration-args;
+                            deploy-args = { inherit root host meta configuration; };
+                            deploy = mkDeployNode deploy-args;
+                          in
+                            lib.optionalAttrs valid {
+                              ${host} = {
+                                inherit configuration;
+                              } // lib.optionalAttrs (has-mkDeployNode && has-deploy-config) {
+                                inherit deploy;
+                              };
+                            }))
+                    ];
+                };
+              };
+              config = {};
+            }));
+            # TODO: put in a more visible place
+            default = {
+              nixos = {
+                predicate = ({ root, host, configurationFiles, ... }:
+                  and [
+                    (! (host == "__template__"))
+                    (hasFiles
+                      [ "configuration.nix" "meta.nix" ]
+                      configurationFiles)
+                  ]);
+                mkHost = ({ root, host, configurationFiles, ... }: let
+                  meta = import "${root}/meta.nix" // {
+                    hostname = host;
+                  };
+                in
+                  mkNixosHost {
+                    inherit root;
+                    inherit meta;
+                    users = genUsers configurationFiles;
+                  });
+                mkDeployNode = ({ root, host, meta, configuration }:
+                  {
+                    inherit (meta.deploy) hostname;
+                    profiles.system = meta.deploy // {
+                      path = inputs.deploy-rs.lib.${meta.system}.activate."nixos" configuration;
+                    };
+                  });
+              };
+              nix-on-droid = {
+                predicate = ({ root, host, configurationFiles, ... }:
+                  and [
+                    (! (host == "__template__"))
+                    (hasFiles
+                      [ "configuration.nix" "home.nix" "meta.nix" ]
+                      configurationFiles)
+                  ]);
+                mkHost = ({ root, host, configurationFiles, ... }: let
+                  meta = import "${root}/meta.nix" // {
+                    hostname = host;
+                  };
+                in
+                  mkNixOnDroidHost {
+                    inherit root;
+                    inherit meta;
+                  });
+              };
+              nix-darwin = {
+                hostsName = "darwinHosts";
+                configurationsName = "darwinConfigurations";
+                predicate = ({ root, host, configurationFiles, ... }:
+                  and [
+                    (! (host == "__template__"))
+                    (hasFiles
+                      [ "configuration.nix" "meta.nix" ]
+                      configurationFiles)
+                    (hasDirectories
+                      [ "home" ]
+                      configurationFiles)
+                  ]);
+                mkHost = ({ root, host, configurationFiles, ... }: let
+                  meta = import "${root}/meta.nix" // {
+                    hostname = host;
+                  };
+                in
+                  mkNixDarwinHost {
+                    inherit root;
+                    inherit meta;
+                    users = genUsers configurationFiles;
+                  });
+                mkDeployNode = ({ root, host, meta, configuration }:
+                  {
+                    inherit (meta.deploy) hostname;
+                    profiles.system = meta.deploy // {
+                      path = inputs.deploy-rs.lib.${meta.system}.activate."darwin" configuration;
+                    };
+                  });
+              };
+              home-manager = {
+                hostsName = "homeHosts";
+                configurationsName = "homeConfigurations";
+                predicate = ({ root, host, configurationFiles, ... }:
+                  and [
+                    (! (host == "__template__"))
+                    (hasFiles
+                      [ "home.nix" "meta.nix" ]
+                      configurationFiles)
+                  ]);
+                mkHost = ({ root, host, configurationFiles, ... }: let
+                  meta = import "${root}/meta.nix" // {
+                    hostname = host;
+                  };
+                in
+                  mkHomeManagerHost {
+                    inherit root;
+                    inherit meta;
+                  });
+              };
+            };
+          };
+          resultConfigurations = lib.mkOption {
+            readOnly = true;
+            default = lib.pipe configurationTypes [
+              (lib.mapAttrs'
+                (configurationType: configurationTypeConfig:
+                  lib.nameValuePair
+                  configurationTypeConfig.configurationsName
+                  (lib.mapAttrs
+                    (host: { configuration, ... }:
+                      configuration)
+                    configurationTypeConfig.resultConfigurations)))
+            ];
+          };
+          resultDeployNodes = lib.mkOption {
+            readOnly = true;
+            default = lib.pipe configurationTypes [
+              (lib.concatMapAttrs
+                (configurationType: configurationTypeConfig:
+                  (lib.concatMapAttrs
+                    (host: { deploy ? null, ... }:
+                      lib.optionalAttrs
+                        (deploy != null)
+                        {
+                          ${host} = deploy;
+                        })
+                    configurationTypeConfig.resultConfigurations)))
+            ];
+          };
+        };
+      });
+      default = {};
+    };
+  };
+
+  config = {
+    # BUG: cannot iterate on `config.flake.autoConfigurations.resultConfigurations`
+    #      because of infinite recursion
+    flake = let
+      ogConfigurationTypes = ["nixos" "nix-on-droid" "nix-darwin" "home-manager"];
+      configurations = lib.pipe ogConfigurationTypes [
+        (lib.map
+          configuration-type-to-outputs-configurations)
+        (lib.flip lib.genAttrs
+          (configurationType:
+            config.flake.autoConfigurations.resultConfigurations.${configurationType}))
+      ];
+      deployNodes = {
+        deploy.nodes = config.flake.autoConfigurations.resultDeployNodes;
+      };
+      deployChecks = {
+        checks =
+          lib.mapAttrs
+            (system: deployLib:
+              deployLib.deployChecks
+              self.deploy)
+            inputs.deploy-rs.lib;
+      };
+      # TODO: lib.something for merging (asserting for no overwrites)
+    in configurations // deployNodes // deployChecks;
   };
 }

modules/flake/deploy/default.nix

@@ -1,45 +0,0 @@
-{ lib, config, self, inputs, ... }:
-
-let
-  inherit (config.lib)
-    accumulateHosts
-    configuration-type-to-deploy-type;
-in
-{
-  flake = {
-    deploy.nodes =
-      accumulateHosts
-        # TODO: nix-on-droid
-        ["nixos" "nix-darwin"]
-        ({ host, system, configuration-type, configuration }:
-          let
-            deploy-config-path =
-              "${config.flake.autoConfigurations.${configuration-type}.dir}/${system}/${host}/deploy.nix";
-            deploy-config =
-              import deploy-config-path;
-          in
-            lib.optionalAttrs
-              (builtins.pathExists deploy-config-path)
-              {
-                ${host} = {
-                  inherit (deploy-config)
-                  hostname;
-                  profiles.system = deploy-config // {
-                    path =
-                      let
-                        deploy-type = configuration-type-to-deploy-type configuration-type;
-                      in
-                        inputs.deploy-rs.lib.${system}.activate.${deploy-type} configuration;
-                  };
-                };
-              }
-        );
-
-    checks =
-      lib.mapAttrs
-        (system: deployLib:
-          deployLib.deployChecks
-            self.deploy)
-        inputs.deploy-rs.lib;
-  };
-}

modules/flake/lib/default.nix

@@ -121,43 +121,5 @@
       (configuration-type:
         builtins.throw
         "Invaild configuration-type \"${configuration-type}\" for deploy-rs deployment");
-
-    accumulateHosts = configuration-types: host-system-configuration-type-configuration-fn:
-      lib.flip lib.concatMapAttrs
-      (lib.genAttrs
-        configuration-types
-        (configuration-type:
-          config.flake.autoConfigurations.${configuration-type}.resultHosts))
-      (configuration-type: hosts:
-        lib.pipe
-        hosts
-        [
-          # Filter out nondirectories
-          (lib.filterAttrs
-            (system: configurations:
-              builtins.isAttrs configurations))
-          # Convert non-template configs into `system-and-config` pairs
-          (lib.concatMapAttrs
-            (system: configurations:
-              (lib.concatMapAttrs
-                (host: configuration:
-                  lib.optionalAttrs
-                  (host != "__template__")
-                  {
-                    ${host} = {
-                      inherit system;
-                      configuration =
-                        let
-                          configurations = configuration-type-to-outputs-configurations configuration-type;
-                        in
-                          self.${configurations}.${host};
-                    };
-                  })
-                configurations)))
-          # Convert each `system-and-config` pair into a *whatever*
-          (lib.concatMapAttrs
-            (host: { system, configuration }:
-              host-system-configuration-type-configuration-fn { inherit host system configuration-type configuration; }))
-        ]);
   };
 }