oxidized: switch to tmpfiles

nixos/modules/services/admin/oxidized.nix

@@ -11,6 +11,8 @@ in
   options.services.oxidized = {
     enable = lib.mkEnableOption "the oxidized configuration backup service";
 
+    package = lib.mkPackageOption pkgs "oxidized" { };
+
     user = lib.mkOption {
       type = lib.types.str;
       default = "oxidized";
@@ -70,7 +72,8 @@ in
     };
 
     routerDB = lib.mkOption {
-      type = lib.types.path;
+      type = lib.types.nullOr lib.types.path;
+      default = null;
       example = lib.literalExpression ''
         pkgs.writeText "oxidized-router.db" '''
           hostname-sw1:powerconnect:username1:password2
@@ -94,18 +97,57 @@ in
       isSystemUser = true;
     };
 
+    systemd.tmpfiles.settings."10-oxidized" =
+      {
+        "${cfg.dataDir}" = {
+          d = {
+            mode = "0750";
+            user = cfg.user;
+            group = cfg.group;
+          };
+        };
+
+        "${cfg.dataDir}/.config" = {
+          d = {
+            mode = "0750";
+            user = cfg.user;
+            group = cfg.group;
+          };
+        };
+
+        "${cfg.dataDir}/.config/oxidized" = {
+          d = {
+            mode = "0750";
+            user = cfg.user;
+            group = cfg.group;
+          };
+        };
+
+        "${cfg.dataDir}/.config/oxidized/config" = {
+          L = {
+            argument = "${cfg.configFile}";
+            user = cfg.user;
+            group = cfg.group;
+          };
+        };
+
+      }
+      // lib.optionalAttrs (cfg.routerDB != null) {
+        "${cfg.dataDir}/.config/oxidized/router.db" = {
+          L = {
+            argument = "${cfg.routerDB}";
+            user = cfg.user;
+            group = cfg.group;
+          };
+        };
+      };
+
     systemd.services.oxidized = {
       wantedBy = [ "multi-user.target" ];
       after = [ "network.target" ];
 
-      preStart = ''
-        mkdir -p ${cfg.dataDir}/.config/oxidized
-        ln -f -s ${cfg.routerDB} ${cfg.dataDir}/.config/oxidized/router.db
-        ln -f -s ${cfg.configFile} ${cfg.dataDir}/.config/oxidized/config
-      '';
-
       serviceConfig = {
-        ExecStart = "${pkgs.oxidized}/bin/oxidized";
+        ExecStart = lib.getExe cfg.package;
         User = cfg.user;
         Group = cfg.group;
         UMask = "0077";