Expose enable_dvr neutron-server option

This option allows to disable dvr API extension exposure, which is
useful when e.g. the deployment is not configured properly to support
DVR routers (for example, snat_mode being legacy for l3 agents, or
backends enabled not supporting DVR).

Change-Id: I61cf078f8d528be757b43e31c961a6124d02c4bb

manifests/server.pp

@@ -114,6 +114,10 @@
 #   Also can be the type of the router on the create request (admin-only attribute).
 #   Defaults to $::os_service_default
 #
+# [*enable_dvr*]
+#   (optional) Setting the "enable_dvr" flag to "False" will disable "dvr" API extension exposure.
+#   Defaults to $::os_service_default
+#
 # [*dhcp_load_type*]
 #   (optional) The resource type whos load is being reported by the agent.
 #   The expected values are either 'networks', 'subnets', 'ports'.
@@ -236,6 +240,7 @@ class neutron::server (
   $enable_new_agents                = $::os_service_default,
   $router_scheduler_driver          = 'neutron.scheduler.l3_agent_scheduler.ChanceScheduler',
   $router_distributed               = $::os_service_default,
+  $enable_dvr                       = $::os_service_default,
   $network_scheduler_driver         = $::os_service_default,
   $dhcp_load_type                   = $::os_service_default,
   $default_availability_zones       = $::os_service_default,
@@ -338,6 +343,7 @@ class neutron::server (
     'DEFAULT/enable_new_agents':                value => $enable_new_agents;
     'DEFAULT/router_scheduler_driver':          value => $router_scheduler_driver;
     'DEFAULT/router_distributed':               value => $router_distributed;
+    'DEFAULT/enable_dvr':                       value => $enable_dvr;
     'DEFAULT/allow_automatic_l3agent_failover': value => $allow_automatic_l3agent_failover;
     'DEFAULT/allow_automatic_dhcp_failover':    value => $allow_automatic_dhcp_failover;
     'DEFAULT/network_scheduler_driver':         value => $network_scheduler_driver;

releasenotes/notes/expose-enable-dvr-c6f94cf187944b79.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    New option ``enable_dvr`` is now exposed. The option is added in Pike, and
+    it allows to disable ``dvr`` API extension exposure when it's known the
+    deployment is not configured to support DVR routers.

spec/classes/neutron_server_spec.rb

@@ -90,15 +90,24 @@ describe 'neutron::server' do
       end
     end
 
-    context 'with DVR enabled' do
+    context 'with DVR enabled for new routers' do
       before :each do
         params.merge!(:router_distributed => true)
       end
-      it 'should enable DVR' do
+      it 'should enable DVR for new routers' do
         is_expected.to contain_neutron_config('DEFAULT/router_distributed').with_value(true)
       end
     end
 
+    context 'with DVR disabled' do
+      before :each do
+        params.merge!(:enable_dvr => false)
+      end
+      it 'should disable DVR' do
+        is_expected.to contain_neutron_config('DEFAULT/enable_dvr').with_value(false)
+      end
+    end
+
     context 'with HA routers enabled' do
       before :each do
         params.merge!(:l3_ha => true)