diff --git a/manifests/federation.pp b/manifests/federation.pp
index fbb23bb54..283ac10ef 100644
--- a/manifests/federation.pp
+++ b/manifests/federation.pp
@@ -7,27 +7,22 @@
 #   This setting ensures that keystone only sends token data back to trusted
 #   servers. This is performed as a precaution, specifically to prevent man-in-
 #   the-middle (MITM) attacks.
-#   Defaults to undef
+#   Defaults to $::os_service_default
 #
 # [*remote_id_attribute*]
 #   (Optional) Value to be used to obtain the entity ID of the Identity
 #   Provider from the environment.
-#   Defaults to undef
+#   Defaults to $::os_service_default
 #
 class keystone::federation (
-  $trusted_dashboards  = undef,
-  $remote_id_attribute = undef,
+  $trusted_dashboards  = $::os_service_default,
+  $remote_id_attribute = $::os_service_default,
 ) {
 
   include keystone::deps
 
   keystone_config {
-    'federation/trusted_dashboard': value  => any2array($trusted_dashboards);
-  }
-
-  if $remote_id_attribute {
-    keystone_config {
-      'federation/remote_id_attribute': value => $remote_id_attribute;
-    }
+    'federation/trusted_dashboard':   value => $trusted_dashboards;
+    'federation/remote_id_attribute': value => $remote_id_attribute;
   }
 }
diff --git a/spec/classes/keystone_federation_spec.rb b/spec/classes/keystone_federation_spec.rb
index 0ab891adf..81aa07676 100644
--- a/spec/classes/keystone_federation_spec.rb
+++ b/spec/classes/keystone_federation_spec.rb
@@ -8,10 +8,27 @@ describe 'keystone::federation' do
     EOS
   end
 
-  let :params do
-    { :trusted_dashboards => ['http://dashboard.example.com'],
-      :remote_id_attribute => 'test_attribute',
-     }
+  shared_examples_for 'keystone::federation' do
+    context 'with defaults' do
+      it 'should configure federation options' do
+        is_expected.to contain_keystone_config('federation/trusted_dashboard').with_value('<SERVICE DEFAULT>')
+        is_expected.to contain_keystone_config('federation/remote_id_attribute').with_value('<SERVICE DEFAULT>')
+      end
+    end
+
+    context 'with optional parameters' do
+      let :params do
+        {
+          :trusted_dashboards  => ['http://dashboard.example.com'],
+          :remote_id_attribute => 'test_attribute',
+        }
+      end
+
+      it 'should configure federation options' do
+        is_expected.to contain_keystone_config('federation/trusted_dashboard').with_value(['http://dashboard.example.com'])
+        is_expected.to contain_keystone_config('federation/remote_id_attribute').with_value('test_attribute')
+      end
+    end
   end
 
   on_supported_os({
@@ -20,14 +37,6 @@ describe 'keystone::federation' do
       facts.merge!(OSDefaults.get_facts({}))
     end
 
-    context 'with optional parameters' do
-      it 'should set federation/trusted_dashboard' do
-        is_expected.to contain_keystone_config('federation/trusted_dashboard').with_value(['http://dashboard.example.com'])
-      end
-
-      it 'should set federation/remote_id_attribute' do
-        is_expected.to contain_keystone_config('federation/remote_id_attribute').with_value('test_attribute')
-      end
-    end
+    it_behaves_like 'keystone::federation'
   end
 end