homu: do not put configuration file in nix

* issue with multiline string values
* slight security problem

nixbld-etc-nixos/homu/nixos-module.nix

@@ -2,40 +2,7 @@
 with lib;
 let
   homu = pkgs.callPackage ./pkg.nix {};
-
-  toToml = key: value:
-    let valueString =
-      if builtins.isString value
-      then "\"" + (builtins.replaceStrings ["\"" "\\"] ["\\\"" "\\\\"] value) + "\""
-      else toString value;
-    in "${key} = ${valueString}\n";
-
-  defaultConfig = {
-    db = {
-      file = "/var/db/homu/main.db";
-    };
-  };
   cfg = config.services.homu;
-  homuConfig = defaultConfig // cfg.config;
-  configFilter = f:
-    filterAttrs (key: value: f value) homuConfig;
-  topLevelConfig =
-    configFilter (value: ! builtins.isAttrs value);
-  configSections =
-    configFilter (value: builtins.isAttrs value);
-
-  configFile = builtins.toFile "config.toml" (
-    builtins.concatStringsSep "" (
-      (attrsets.mapAttrsToList toToml topLevelConfig) ++
-      (builtins.concatLists (attrsets.mapAttrsToList
-        (sectionName: sectionConfig:
-          [ "[${sectionName}]\n" ] ++
-          (attrsets.mapAttrsToList toToml sectionConfig)
-        ) configSections)
-      ))
-  );
-
-  dbDir = dirOf homuConfig.db.file;
 in
 
 {
@@ -45,16 +12,21 @@ in
       default = false;
       description = "Enable the bot";
     };
+    dbDir = mkOption {
+      type = types.str;
+      default = "/var/db/homu";
+      description = "Path to the database file (use the same path in config.toml)";
+    };
     config = mkOption {
-      description = "Structured data for config.toml";
-      type = with types; attrsOf unspecified;
+      description = "Location of config.toml";
+      type = types.str;
     };
   };
 
   config = mkIf cfg.enable {
     users.users.homu = {
       group = "homu";
-      home = dbDir;
+      home = cfg.dbDir;
       createHome = true;
     };
     users.groups.homu = {};
@@ -65,7 +37,7 @@ in
       after    = [ "network.target" ];
       serviceConfig = {
         Type = "simple";
-        ExecStart = "${homu}/bin/homu -c ${configFile}";
+        ExecStart = "${homu}/bin/homu -c ${cfg.config}";
 
         Restart = "always";
         RestartSec = "5sec";