add service module for system activation

3 files changed, 55 insertions, 13 deletions

diff --git a/modules/services/activate-system.nix b/modules/services/activate-system.nix
new file mode 100644
index 0000000..a92576f
--- /dev/null
+++ b/modules/services/activate-system.nix
@@ -0,0 +1,47 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  cfg = config.services.activate-system;
+
+  activateScript = pkgs.writeScript "activate-system" ''
+    #! ${pkgs.stdenv.shell}
+
+    # Make this configuration the current configuration.
+    # The readlink is there to ensure that when $systemConfig = /system
+    # (which is a symlink to the store), /run/current-system is still
+    # used as a garbage collection root.
+    ln -sfn $(cat ${config.system.profile}/systemConfig) /run/current-system
+
+    # Prevent the current configuration from being garbage-collected.
+    ln -sfn /run/current-system /nix/var/nix/gcroots/current-system
+  '';
+
+in
+
+{
+  options = {
+    services.activate-system = {
+
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Whether to activate system at boot time.
+        '';
+      };
+
+    };
+  };
+
+  config = {
+
+    launchd.daemons.activate-system = mkIf cfg.enable {
+      serviceConfig.Program = "${activateScript}";
+      serviceConfig.RunAtLoad = true;
+    };
+
+  };
+}
diff --git a/modules/system/activation-scripts.nix b/modules/system/activation-scripts.nix
index fe3131d..fda882f 100644
--- a/modules/system/activation-scripts.nix
+++ b/modules/system/activation-scripts.nix
@@ -34,19 +34,6 @@ in
 
   config = {
 
-    system.build.activate = pkgs.writeScript "activate-system" ''
-      #! ${pkgs.stdenv.shell}
-
-      # Make this configuration the current configuration.
-      # The readlink is there to ensure that when $systemConfig = /system
-      # (which is a symlink to the store), /run/current-system is still
-      # used as a garbage collection root.
-      ln -sfn $(cat /nix/var/nix/profiles/system/systemConfig) /run/current-system
-
-      # Prevent the current configuration from being garbage-collected.
-      ln -sfn /run/current-system /nix/var/nix/gcroots/current-system
-    '';
-
     system.activationScripts.script.text = ''
       #! ${pkgs.stdenv.shell}
 
diff --git a/modules/system/default.nix b/modules/system/default.nix
index 9cf190e..d1d9f72 100644
--- a/modules/system/default.nix
+++ b/modules/system/default.nix
@@ -27,6 +27,14 @@ in
       '';
     };
 
+    system.profile = mkOption {
+      type = types.path;
+      default = "/nix/var/nix/profiles/system";
+      description = ''
+        Profile to use for the system.
+      '';
+    };
+
     system.nixdarwinLabel = mkOption {
       type = types.str;
       default = "16.09";