taskwarrior-sync: add service module

modules/misc/news.nix

@@ -1137,6 +1137,14 @@ in
           A new module is available: 'programs.broot'.
         '';
       }
+
+      {
+        time = "2019-07-17T19:30:29+00:00";
+        condition = hostPlatform.isLinux;
+        message = ''
+          A new module is available: 'services.taskwarrior-sync'.
+        '';
+      }
     ];
   };
 }

modules/modules.nix

@@ -124,6 +124,7 @@ let
     (loadModule ./services/syncthing.nix { })
     (loadModule ./services/taffybar.nix { })
     (loadModule ./services/tahoe-lafs.nix { })
+    (loadModule ./services/taskwarrior-sync.nix { condition = hostPlatform.isLinux; })
     (loadModule ./services/udiskie.nix { })
     (loadModule ./services/unclutter.nix { })
     (loadModule ./services/window-managers/awesome.nix { })

modules/services/taskwarrior-sync.nix

@@ -0,0 +1,59 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  cfg = config.services.taskwarrior-sync;
+
+in
+
+{
+  meta.maintainers = with maintainers; [ minijackson pacien ];
+
+  options.services.taskwarrior-sync = {
+    enable = mkEnableOption "Taskwarrior periodic sync";
+
+    frequency = mkOption {
+      type = types.str;
+      default = "*:0/5";
+      description = ''
+        How often to run <literal>taskwarrior sync</literal>. This
+        value is passed to the systemd timer configuration as the
+        <literal>OnCalendar</literal> option. See
+        <citerefentry>
+          <refentrytitle>systemd.time</refentrytitle>
+          <manvolnum>7</manvolnum>
+        </citerefentry>
+        for more information about the format.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.user.services.taskwarrior-sync = {
+      Unit = {
+        Description = "Taskwarrior sync";
+        PartOf = [ "network-online.target" ];
+      };
+      Service = {
+        CPUSchedulingPolicy = "idle";
+        IOSchedulingClass = "idle";
+        ExecStart = "${pkgs.taskwarrior}/bin/task synchronize";
+      };
+    };
+
+    systemd.user.timers.taskwarrior-sync = {
+      Unit = {
+        Description = "Taskwarrior periodic sync";
+      };
+      Timer = {
+        Unit = "taskwarrior-sync.service";
+        OnCalendar = cfg.frequency;
+      };
+      Install = {
+        WantedBy = [ "timers.target" ];
+      };
+    };
+  };
+}