feat: add module to allow extending configuration of other nodes

modules/distributed-config.nix

@@ -0,0 +1,46 @@
+{
+  config,
+  extraLib,
+  lib,
+  nodeName,
+  colmenaNodes,
+  ...
+}: let
+  inherit
+    (lib)
+    attrNames
+    concatMap
+    filter
+    mdDoc
+    mkOption
+    types
+    unique
+    subtractLists
+    ;
+
+  inherit
+    (extraLib)
+    mergeToplevelConfigs
+    ;
+in {
+  options.nodes = mkOption {
+    type = types.attrsOf types.unspecified;
+    default = {};
+    description = mdDoc "Allows extending the configuration of other machines.";
+  };
+
+  config = let
+    otherNodes = filter (n: n != nodeName) (attrNames colmenaNodes);
+    foreignConfigs = map (n: colmenaNodes.${n}.config.nodes.${nodeName} or {}) otherNodes;
+    toplevelAttrs = ["age" "networking" "systemd" "services"];
+  in
+    {
+      assertions =
+        map (n: {
+          assertion = false;
+          message = "Cannot extend configuration using nodes.${n} because the given node is not a registered or not a first-class nixos node (microvm's can't be extended right now).";
+        })
+        (subtractLists (attrNames colmenaNodes) (attrNames config.nodes));
+    }
+    // mergeToplevelConfigs toplevelAttrs foreignConfigs;
+}

nix/generate-node.nix

@@ -18,7 +18,7 @@ in {
   pkgs = self.pkgs.${nodeMeta.system};
   specialArgs = {
     inherit (nixpkgs) lib;
-    inherit (self) extraLib nodes stateVersion;
+    inherit (self) extraLib nodes stateVersion colmenaNodes;
     inherit inputs nodeName;
     # Only set the nodePath if it is an actual directory
     nodePath =