nixos/networkmanager: clean up plugin handling

There is no point in having a special option to enable strongswan, when
we can just parse the intent from the plugin list instead.

Also pick up relevant runtime dependency information from the plugin
package instead of providing additional options or hardcoding them.

nixos/modules/services/networking/networkmanager.nix

@@ -127,15 +127,20 @@ let
     '';
   };
 
+  concatPluginAttrs = attr: lib.concatMap (plugin: plugin.${attr} or [ ]) cfg.plugins;
+  pluginRuntimeDeps = concatPluginAttrs "networkManagerRuntimeDeps";
+  pluginDbusDeps = concatPluginAttrs "networkManagerDbusDeps";
+  pluginTmpfilesRules = concatPluginAttrs "networkManagerTmpfilesRules";
+
   packages =
     [
       cfg.package
     ]
     ++ cfg.plugins
+    ++ pluginRuntimeDeps
     ++ lib.optionals (!delegateWireless && !enableIwd) [
       pkgs.wpa_supplicant
     ];
-
 in
 {
 
@@ -390,19 +395,6 @@ in
         '';
       };
 
-      enableStrongSwan = mkOption {
-        type = types.bool;
-        default = false;
-        description = ''
-          Enable the StrongSwan plugin.
-
-          If you enable this option the
-          `networkmanager_strongswan` plugin will be added to
-          the {option}`networking.networkmanager.plugins` option
-          so you don't need to do that yourself.
-        '';
-      };
-
       ensureProfiles = {
         profiles =
           with lib.types;
@@ -523,6 +515,11 @@ in
       [ "networking" "networkmanager" "fccUnlockScripts" ]
       [ "networking" "modemmanager" "fccUnlockScripts" ]
     )
+    (mkRemovedOptionModule [
+      "networking"
+      "networkmanager"
+      "enableStrongSwan"
+    ] "Pass `pkgs.networkmanager_strongswan` into `networking.networkmanager.plugins` instead.")
   ];
 
   ###### implementation
@@ -597,13 +594,10 @@ in
 
     systemd.tmpfiles.rules = [
       "d /etc/NetworkManager/system-connections 0700 root root -"
-      "d /etc/ipsec.d 0700 root root -"
-      "d /var/lib/NetworkManager-fortisslvpn 0700 root root -"
-
       "d /var/lib/misc 0755 root root -" # for dnsmasq.leases
       # ppp isn't able to mkdir that directory at runtime
       "d /run/pppd/lock 0700 root root -"
-    ];
+    ] ++ pluginTmpfilesRules;
 
     systemd.services.NetworkManager = {
       wantedBy = [ "multi-user.target" ];
@@ -642,6 +636,7 @@ in
       wantedBy = [ "multi-user.target" ];
       before = [ "network-online.target" ];
       after = [ "NetworkManager.service" ];
+      path = pluginRuntimeDeps;
       script =
         let
           path = id: "/run/NetworkManager/system-connections/${id}.nmconnection";
@@ -680,10 +675,6 @@ in
         ];
       })
 
-      (mkIf cfg.enableStrongSwan {
-        networkmanager.plugins = [ pkgs.networkmanager_strongswan ];
-      })
-
       (mkIf enableIwd {
         wireless.iwd.enable = true;
       })
@@ -710,11 +701,10 @@ in
     security.polkit.enable = true;
     security.polkit.extraConfig = polkitConf;
 
-    services.dbus.packages =
-      packages
-      ++ optional cfg.enableStrongSwan pkgs.strongswanNM
-      ++ optional (cfg.dns == "dnsmasq") pkgs.dnsmasq;
+    services.dbus.packages = packages ++ pluginDbusDeps ++ optional (cfg.dns == "dnsmasq") pkgs.dnsmasq;
 
     services.udev.packages = packages;
+
+    systemd.services.NetworkManager.path = pluginRuntimeDeps;
   };
 }