backup: add dl module

backupdl-module.nix

@@ -0,0 +1,56 @@
+{ config, pkgs, lib, ... }:
+with lib;
+let
+  makeBackup = pkgs.writeScript "make-backupdl" ''
+    #!${pkgs.bash}/bin/bash
+
+    set -e
+
+    export PATH=${pkgs.rsync}/bin:${pkgs.openssh}/bin
+
+    FILENAME=backup-`${pkgs.coreutils}/bin/date +%F`.tar.bz2.gpg
+
+    ssh nixbld.m-labs.hk mlabs-backup > /hdd/backupdl/backupdl/$FILENAME
+    rsync -az nixbld.m-labs.hk:/var/lib/nextcloud/data /hdd/backupdl/nextcloud
+  '';
+
+  cfg = config.services.backupdl;
+in
+{
+  options.services.backupdl = {
+    enable = mkOption {
+      type = types.bool;
+      default = false;
+      description = "Enable backups";
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.services.backupdl = {
+      description = "Nixbld backups download";
+      serviceConfig = {
+        Type = "oneshot";
+        User = "backupdl";
+        Group = "backupdl";
+        ExecStart = "${makeBackup}";
+      };
+    };
+
+    users.users.backupdl = {
+      name = "backupdl";
+      group = "backupdl";
+      description = "Nixbld backups download";
+      isSystemUser = true;
+      createHome = true;
+      home = "/hdd/backupdl";
+      useDefaultShell = true;
+    };
+    users.extraGroups.backupdl = {};
+
+    systemd.timers.backupdl = {
+      description = "Nixbld backups download";
+      wantedBy = [ "timers.target" ];
+      timerConfig.OnCalendar = "wednesday,sunday *-*-* 08:00:00";
+    };
+  };
+}