GRE Tunnel to systemd service unit

modules/gre-tunnel/default.nix

@@ -5,6 +5,35 @@ with lib;
 let
   cfg = config.clerie.gre-tunnel;
 
+  generateInterfaceUnit = isIPv6: name: tunnel:
+    nameValuePair "gre-tunnel-${name}" {
+        description = "GRE Tunnel - ${name}";
+        requires = [ "network-online.target" ];
+        after = [ "network.target" "network-online.target" ];
+        wantedBy = [ "multi-user.target" ];
+        environment.DEVICE = name;
+        path = with pkgs; [ iproute ];
+
+        serviceConfig = {
+          Type = "oneshot";
+          RemainAfterExit = true;
+        };
+
+        script = ''
+          ${tunnel.preSetup}
+          ip${optionalString isIPv6 " -6"} tunnel add ${name} mode gre remote ${tunnel.remote} local ${tunnel.local}
+          ip link set ${name} up
+          ip${optionalString isIPv6 " -6"} a add ${tunnel.address} dev ${name}
+          ${tunnel.postSetup}
+        '';
+
+        postStop = ''
+          ip link set ${name} down
+          ip tunnel del ${name}
+          ${tunnel.postShutdown}
+        '';
+      };
+
   checkOpts = { config, ... }@moduleAttrs: {
     options = {
       remote = mkOption {
@@ -16,6 +45,18 @@ let
       address = mkOption {
         type = types.str;
       };
+      preSetup = mkOption {
+        type = types.str;
+        default = "";
+      };
+      postSetup = mkOption {
+        type = types.str;
+        default = "";
+      };
+      postShutdown = mkOption {
+        type = types.str;
+        default = "";
+      };
     };
   };
 
@@ -25,28 +66,18 @@ in {
       enable = mkEnableOption "Declarative Policy-Routing";
       ipv6 = mkOption {
         type = with types; attrsOf (submodule checkOpts);
+        default = {};
       };
       ipv4 = mkOption {
         type = with types; attrsOf (submodule checkOpts);
+        default = {};
       };
     };
   };
 
   config = mkIf cfg.enable {
-    clerie.gre-tunnel.rules = [
-      { rule = "lookup main"; prio = 32000; }
-    ];
-    networking.localCommands = ''
-      ${concatMapStringsSep "\n" ( mapAttrsToList ( name: tunnel: ''
-      ip -6 tunnel add ${name} mode gre remote ${tunnel.remote} local ${tunnel.local}
-      ip link set ${name} up
-      ip -6 a add ${tunnel.address} dev ${name}
-      '') cfg.ipv6 ) }
-      ${concatMapStringsSep "\n" ( mapAttrsToList ( name: tunnel: ''
-      ip -4 tunnel add ${name} mode gre remote ${tunnel.remote} local ${tunnel.local}
-      ip link set ${name} up
-      ip -4 a add ${tunnel.address} dev ${name}
-      '') cfg.ipv4 ) }
-    '';
+    systemd.services =
+    (mapAttrsToList (generateInterfaceUnit false) cfg.ipv4)
+    ++ (mapAttrsToList (generateInterfaceUnit true) cfg.ipv6);
   };
 }