diff --git a/modules/compute/compute.nix b/modules/compute/compute.nix
index 33f3d59..a085916 100644
--- a/modules/compute/compute.nix
+++ b/modules/compute/compute.nix
@@ -2,6 +2,7 @@
 { ... }:
 {
   imports = [
+    ../generic/controller-host-entry.nix
     (import ./neutron.nix { inherit neutron; })
     (import ./nova.nix { inherit nova; })
   ];
diff --git a/modules/controller/openstack-controller.nix b/modules/controller/openstack-controller.nix
index b49c81d..321f432 100644
--- a/modules/controller/openstack-controller.nix
+++ b/modules/controller/openstack-controller.nix
@@ -25,6 +25,7 @@ in
 {
   imports = [
     ./generic.nix
+    ../generic/controller-host-entry.nix
     (import ./keystone.nix { inherit keystone; })
     (import ./glance.nix { inherit glance; })
     (import ./placement.nix { inherit placement; })
diff --git a/modules/generic/controller-host-entry.nix b/modules/generic/controller-host-entry.nix
new file mode 100644
index 0000000..1a80a62
--- /dev/null
+++ b/modules/generic/controller-host-entry.nix
@@ -0,0 +1,19 @@
+{ lib, config, ... }:
+with lib;
+{
+  options.openstack = {
+    controllerIP = mkOption {
+      type = types.str;
+      description = ''
+        IP address of the controller. Will be used to make a /etc/hosts entry
+        to make the controller available via "controller".
+      '';
+    };
+  };
+
+  config = {
+    networking.extraHosts = ''
+      ${config.openstack.controllerIP} controller controller.local
+    '';
+  };
+}
diff --git a/modules/testing/default.nix b/modules/testing/default.nix
index 6ac9f2b..413d4ce 100644
--- a/modules/testing/default.nix
+++ b/modules/testing/default.nix
@@ -13,26 +13,30 @@ let
   common =
     { pkgs, lib, ... }:
     {
-      system.stateVersion = lib.trivial.release;
+      imports = [
+        ../generic/controller-host-entry.nix
+      ];
 
-      services.getty.autologinUser = "root";
+      config = {
+        system.stateVersion = lib.trivial.release;
 
-      networking.extraHosts = ''
-        10.0.0.11 controller controller.local
-      '';
+        services.getty.autologinUser = "root";
 
-      networking = {
-        useDHCP = false;
-        networkmanager.enable = false;
-        useNetworkd = true;
-        firewall.enable = false;
-      };
+        openstack.controllerIP = "10.0.0.11";
 
-      environment.systemPackages = [
-        pkgs.openstackclient
-      ];
+        networking = {
+          useDHCP = false;
+          networkmanager.enable = false;
+          useNetworkd = true;
+          firewall.enable = false;
+        };
 
-      environment.variables = adminEnv;
+        environment.systemPackages = [
+          pkgs.openstackclient
+        ];
+
+        environment.variables = adminEnv;
+      };
     };
 in
 {