nixos/openvpn: add support for resolvconf

The update-resolve-conf script from the update-resolv-conf
package is very useful and should work in most of the common
cases, so this adds an option to enable it. The option is
disabled by default for backwards compatibility.

1 files changed, 19 insertions, 3 deletions

diff --git a/nixos/modules/services/networking/openvpn.nix b/nixos/modules/services/networking/openvpn.nix
index a96888dec86..82173a841a3 100644
--- a/nixos/modules/services/networking/openvpn.nix
+++ b/nixos/modules/services/networking/openvpn.nix
@@ -29,21 +29,27 @@ let
         done
 
         ${cfg.up}
+        ${optionalString cfg.updateResolvConf
+           "${pkgs.update-resolv-conf}/libexec/openvpn/update-resolv-conf"}
       '';
 
       downScript = ''
         #! /bin/sh
         export PATH=${path}
+        ${optionalString cfg.updateResolvConf
+           "${pkgs.update-resolv-conf}/libexec/openvpn/update-resolv-conf"}
         ${cfg.down}
       '';
 
       configFile = pkgs.writeText "openvpn-config-${name}"
         ''
           errors-to-stderr
-          ${optionalString (cfg.up != "" || cfg.down != "") "script-security 2"}
+          ${optionalString (cfg.up != "" || cfg.down != "" || cfg.updateResolvConf) "script-security 2"}
           ${cfg.config}
-          ${optionalString (cfg.up != "") "up ${pkgs.writeScript "openvpn-${name}-up" upScript}"}
-          ${optionalString (cfg.down != "") "down ${pkgs.writeScript "openvpn-${name}-down" downScript}"}
+          ${optionalString (cfg.up != "" || cfg.updateResolvConf)
+              "up ${pkgs.writeScript "openvpn-${name}-up" upScript}"}
+          ${optionalString (cfg.down != "" || cfg.updateResolvConf)
+              "down ${pkgs.writeScript "openvpn-${name}-down" downScript}"}
         '';
 
     in {
@@ -145,6 +151,16 @@ in
           description = "Whether this OpenVPN instance should be started automatically.";
         };
 
+        updateResolvConf = mkOption {
+          default = false;
+          type = types.bool;
+          description = ''
+            Use the script from the update-resolv-conf package to automatically
+            update resolv.conf with the DNS information provided by openvpn. The
+            script will be run after the "up" commands and before the "down" commands.
+          '';
+        };
+
       };
 
     };