starting safe_reboot

common/global/default.nix

@@ -16,6 +16,7 @@
     ./nh.nix
     ./nix.nix
     ./programs.nix
+    ./safe_reboot.nix
     ./ssh.nix
     ./snapshot_manager.nix
   ];
@@ -49,6 +50,11 @@
       PYTHONPATH = "${inputs.self}/";
     };
 
+    safe_reboot = {
+      enable = lib.mkDefault true;
+      datasetPrefix = "root_pool/";
+    };
+
     zfs = {
       trim.enable = lib.mkDefault true;
       autoScrub.enable = lib.mkDefault true;

common/global/safe_reboot.nix

@@ -0,0 +1,56 @@
+{
+  config,
+  inputs,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  cfg = config.services.safe_reboot;
+  python_command =
+    lib.escapeShellArgs (
+      [
+        "${pkgs.my_python}/bin/python"
+        "-m"
+        "python.tools.safe_reboot"
+      ]
+      ++ lib.optionals (cfg.drivePath != null) [ cfg.drivePath ]
+      ++ [
+        "--dataset-prefix"
+        cfg.datasetPrefix
+        "--check-only"
+      ]
+    );
+in
+{
+  options.services.safe_reboot = {
+    enable = lib.mkEnableOption "Safe reboot dataset/drive validation";
+    datasetPrefix = lib.mkOption {
+      type = lib.types.str;
+      default = "root_pool/";
+      description = "Dataset prefix that must have exec enabled before rebooting.";
+    };
+    drivePath = lib.mkOption {
+      type = lib.types.nullOr lib.types.str;
+      default = null;
+      description = "Drive path that must exist before rebooting. Set to null to skip.";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    systemd.services.safe-reboot-check = {
+      description = "Safe reboot validation";
+      before = [ "systemd-reboot.service" ];
+      wantedBy = [ "reboot.target" ];
+      partOf = [ "reboot.target" ];
+      path = [ pkgs.zfs ];
+      environment = {
+        PYTHONPATH = "${inputs.self}/";
+      };
+      serviceConfig = {
+        Type = "oneshot";
+        ExecStart = python_command;
+      };
+    };
+  };
+}