Merge pull request #332 from nix-community/feat/modules-config

feat: validate config using modules

flake.nix

@@ -163,9 +163,7 @@
       import ./src rec {
         externalDir = externalDirFor."${system}";
         inherit externalPaths externalSources inputs lib pkgs;
-        config = {
-          inherit overridesDirs;
-        };
+        config = {inherit overridesDirs;};
       });
 
     docsCli = forAllSystems (

src/default.nix

@@ -6,13 +6,16 @@
   pkgs ? import <nixpkgs> {},
   lib ? pkgs.lib,
   nix ? pkgs.nix,
-  # default to empty dream2nix config
+  # already validated config.
+  # this is mainly used by src/lib.nix since it loads the config beforehand.
+  loadedConfig ? null,
+  # default to empty dream2nix config. This is assumed to be not loaded.
   config ?
-  # if called via CLI, load config via env
-  if builtins ? getEnv && builtins.getEnv "dream2nixConfig" != ""
-  then (import ./utils/config.nix).loadConfig (builtins.toPath (builtins.getEnv "dream2nixConfig"))
-  # load from default directory
-  else (import ./utils/config.nix).loadConfig {},
+    if builtins ? getEnv && builtins.getEnv "dream2nixConfig" != ""
+    # if called via CLI, load config via env
+    then builtins.toPath (builtins.getEnv "dream2nixConfig")
+    # load from default directory
+    else {},
   /*
   Inputs that are not required for building, and therefore not need to be
   copied alongside a dream2nix installation.
@@ -50,13 +53,19 @@ in let
 
   l = lib // builtins;
 
-  config = (import ./utils/config.nix).loadConfig argsConfig;
+  config =
+    if loadedConfig != null
+    then loadedConfig
+    else
+      import ./modules/config.nix {
+        inherit lib;
+        rawConfig = argsConfig;
+      };
 
   configFile = pkgs.writeText "dream2nix-config.json" (b.toJSON config);
 
   dlib = import ./lib {
-    inherit lib;
-    config = (import ./utils/config.nix).loadConfig config;
+    inherit lib config;
     inherit framework;
   };
 

src/lib.nix

@@ -13,10 +13,16 @@
 
   initDream2nix = config: pkgs:
     import ./default.nix
-    {inherit config inputs pkgs externalPaths externalSources;};
+    {
+      loadedConfig = config;
+      inherit inputs pkgs externalPaths externalSources;
+    };
 
   loadConfig = config'': let
-    config' = (import ./utils/config.nix).loadConfig config'';
+    config' = import ./modules/config.nix {
+      rawConfig = config'';
+      inherit lib;
+    };
 
     config =
       config'
@@ -197,7 +203,7 @@ in {
   inherit init makeFlakeOutputs makeFlakeOutputsForIndexes;
   dlib = import ./lib {
     inherit lib;
-    config = (import ./utils/config.nix).loadConfig {};
+    config = loadConfig {};
   };
   riseAndShine = throw "Use makeFlakeOutputs instead of riseAndShine.";
 }

src/modules/config.nix

@@ -0,0 +1,29 @@
+{
+  rawConfig,
+  lib,
+}: let
+  b = builtins;
+
+  # loads attrs either from s:
+  #   - json file
+  #   - json string
+  #   - attrset (no changes)
+  loadAttrs = input:
+    if b.isPath input
+    # discarding context here should be fine since we read the text from
+    # a path, which will be realized and nothing else will need to be realized
+    then b.fromJSON (b.unsafeDiscardStringContext (b.readFile input))
+    else if b.isString input
+    then b.fromJSON input
+    else if b.isAttrs input
+    then input
+    else throw "input for loadAttrs must be json file or string or attrs";
+
+  config = loadAttrs rawConfig;
+
+  evaled = lib.evalModules {
+    modules = [./config {inherit config;}];
+    specialArgs = {inherit lib;};
+  };
+in
+  evaled.config

src/modules/config/default.nix

@@ -0,0 +1,5 @@
+{
+  imports = [
+    ./interface.nix
+  ];
+}

src/modules/config/interface.nix

@@ -0,0 +1,43 @@
+{lib, ...}: let
+  l = lib // builtins;
+  t = l.types;
+in {
+  options = {
+    overridesDirs = l.mkOption {
+      type = t.listOf t.path;
+      default = [];
+      description = ''
+        Override directories to pull overrides from.
+      '';
+    };
+    packagesDir = l.mkOption {
+      type = t.str;
+      default = "./dream2nix-packages";
+      description = ''
+        Relative path to the project root to put generated dream-lock files in.
+      '';
+    };
+    projectRoot = l.mkOption {
+      type = t.nullOr t.path;
+      default = null;
+      description = ''
+        Absolute path to the root of this project.
+      '';
+    };
+    repoName = l.mkOption {
+      type = t.nullOr t.str;
+      default = null;
+      description = ''
+        Name of the repository this project is in.
+      '';
+    };
+    modules = l.mkOption {
+      type = t.listOf (t.oneOf [t.attrs t.path (t.functionTo t.attrs)]);
+      default = [];
+      description = ''
+        Extra modules to import in while evaluating the dream2nix framework.
+        This allows you to add new discoverers, translators, builders etc. and lets you override existing ones.
+      '';
+    };
+  };
+}