Enable "port_forwarding" feature in neutron ML2 ovs environment

This patch enables port_forwarding service plugin and L3 agent's
extension in case of ML2/OVS environment.
It don't enable it in ML2/OVN cases as networking-ovn don't support
port_forwarding yet.

This patch also adds NeutronL3AgentExtensions config option for
Neutron L3 agent.
This new option is used to enable "port_forwarding" extension on L3
agent.

Change-Id: I2417f9f6a436ae7a3820e16fdf6210099807b651

deployment/neutron/neutron-l3-container-puppet.yaml

@@ -122,6 +122,11 @@ parameters:
                  parameter should be unset.
     type: string
     default: ''
+  NeutronL3AgentExtensions:
+    default: ""
+    description: |
+        Comma-separated list of extensions enabled for the Neutron L3 agent.
+    type: comma_delimited_list
 
 conditions:
   keepalived_wrapper_enabled: {equals: [{get_param: NeutronEnableKeepalivedWrapper}, true]}
@@ -132,6 +137,7 @@ conditions:
   service_debug_unset: {equals : [{get_param: NeutronWrapperDebug}, false]}
   external_network_bridge_empty: {equals : [{get_param: NeutronExternalNetworkBridge}, "''"]}
   az_unset: {equals: [{get_param: NeutronL3AgentAvailabilityZone}, '']}
+  l3_agent_extensions_empty: {equals : [{get_param: NeutronL3AgentExtensions}, "''"]}
 
 resources:
 
@@ -215,6 +221,10 @@ outputs:
             - az_unset
             - {}
             - neutron::agents::l3::availability_zone: {get_param: NeutronL3AgentAvailabilityZone}
+            if:
+            - l3_agent_extensions_empty
+            - {}
+            - neutron::agents::l3::extensions: {get_param: NeutronL3AgentExtensions}
       service_config_settings:
         map_merge:
           - get_attr: [NeutronBase, role_data, service_config_settings]

environments/services/neutron-ovs.yaml

@@ -28,8 +28,10 @@ parameter_defaults:
 
   NeutronTypeDrivers: 'vxlan,vlan,flat,gre'
   NeutronNetworkType: 'vxlan'
-  NeutronServicePlugins: 'router,qos,segments,trunk'
+  NeutronServicePlugins: 'router,qos,segments,trunk,port_forwarding'
   NeutronVniRanges: ['1:65536', ]
   KernelIpNonLocalBind: 0
 
   NeutronEnableDVR: false
+
+  NeutronL3AgentExtensions: "port_forwarding"

releasenotes/notes/enable-port-forwarding-in-neutron-956cb21a3310e881.yaml

@@ -0,0 +1,8 @@
+---
+other:
+  - |
+    Add "port_forwarding" service plugin and L3 agent extension to be enabled
+    by default when Neutron ML2 plugin with OVS driver is used.
+    New config option "NeutronL3AgentExtensions" is also added. This
+    new option allows to set list of L3 agent's extensions which should be
+    used by agent.