Add Rupert’s configuration

options/btrfs-scrub.nix

@@ -0,0 +1,56 @@
+{ pkgs, utils, lib, config, ... }:
+with lib;
+let
+    cfg = config.services.btrfsScrub;
+in
+{
+    options.services.btrfsScrub = {
+        enable = mkEnableOption "Periodically run btrfs-scrub on filesystems";
+        enableFailureEmail = mkOption {
+            type = types.bool;
+            default = true;
+            description = mdDoc "Send e-mail on scrub failure";
+        };
+        paths = mkOption {
+            type = with types; attrsOf (submodule {
+                options = {
+                    onCalendar = mkOption {
+                        type = str;
+                        default = "*-*-* 02:00:00";
+                    };
+                };
+            });
+        };
+    };
+
+    config.services.statusEmail.enable = mkIf (cfg.enable && cfg.enableFailureEmail) true;
+
+    config.systemd.services."btrfs-scrub@" = mkIf cfg.enable {
+        unitConfig = {
+            Description = "Scrub btrfs volume %I";
+            OnFailure = mkIf cfg.enableFailureEmail "status-email@%n.service";
+        };
+        serviceConfig = {
+            Type = "simple";
+            ExecStart = "${pkgs.btrfs-progs}/bin/btrfs scrub start -B -d %f";
+            # ExecStop = "-${pkgs.btrfs-progs}/bin/btrfs scrub cancel %f";
+            Nice = 19;
+        };
+    };
+
+    config.systemd.timers = mkIf cfg.enable (mapAttrs' (name: value:
+    let
+        pathEscaped = utils.escapeSystemdPath name;
+    in
+    nameValuePair "btrfs-scrub-${pathEscaped}"
+    {
+        wantedBy = [ "timers.target" ];
+        enable = true;
+        timerConfig = {
+            Unit = "btrfs-scrub@${pathEscaped}.service";
+            OnCalendar = value.onCalendar;
+            RandomizedDelaySec = "1h";
+            Persistent = true;
+        };
+    }) cfg.paths);
+}