Disable neutron-vpnaas-agent

The Neutron VPNaaS agent has been dropped in the Queens release
and replaced by a plugin in L3 agent[1].

[1]: https://docs.openstack.org/releasenotes/neutron-vpnaas/queens.html

Change-Id: Idb171b3a242483fc2bb9cf837c815a6fb6d3a0de

templates/l3_agent.ini.j2

@@ -21,24 +21,35 @@ ha_vrrp_auth_type = {{ neutron_ha_vrrp_auth_type }}
 # Metadata
 enable_metadata_proxy = True
 
-{% if neutron_fwaas | bool %}
+# L3 plugins
+{% set l3_agent_plugins = [] %}
 
+{% if neutron_fwaas | bool %}
+# FWaaS
+{% set _ = l3_agent_plugins.append("fwaas") %}
 [fwaas]
 enabled = true
 driver = iptables
 agent_version = v1
+{% endif %}
 
-[AGENT]
+{% if neutron_fwaas_v2 | bool %}
-extensions = fwaas
+# FWaaS v2
-
+{% set _ = l3_agent_plugins.append("fwaas_v2") %}
-{% elif neutron_fwaas_v2 | bool %}
-
 [fwaas]
 enabled = true
 driver = iptables_v2
 agent_version = v2
-
+{% endif %}
-[AGENT]
+
-extensions = fwaas_v2
+{% if neutron_vpnaas | bool %}
-
+# VPNaaS
+{% set _ = l3_agent_plugins.append("vpnaas") %}
+[vpnagent]
+vpn_device_driver = {{ neutron_driver_vpnaas }}
+{% endif %}
+
+{% if l3_agent_plugins|length > 1 %}
+[AGENT]
+extensions = {{ l3_agent_plugins | join(',') }}
 {% endif %}

templates/vpnaas_agent.ini.j2

@@ -1,9 +0,0 @@
-# {{ ansible_managed }}
-
-[DEFAULT]
-external_network_bridge = {{ neutron_external_network_bridge }}
-
-interface_driver = {{ neutron_plugins[neutron_plugin_type].driver_interface }}
-
-[vpnagent]
-vpn_device_driver = {{ neutron_driver_vpnaas }}

vars/main.yml

@@ -447,10 +447,14 @@ neutron_services:
     config_type: "ini"
     init_config_overrides: "{{ neutron_bgp_dragent_init_overrides }}"
     start_order: 3
+  # TODO(mnaser): neutron-vpnaas-agent binary was dropped in Queens
+  #               and replaced by a plugin to neutron-l3-agent.  We missed
+  #               this in Queens, so let's remove this in T to disable
+  #               the service.
   neutron-vpnaas-agent:
     group: neutron_l3_agent
     service_name: neutron-vpn-agent
-    service_en: "{{ neutron_vpnaas | bool }}"
+    service_en: false
     service_conf_path: "{{ neutron_conf_dir }}"
     service_conf: vpnaas_agent.ini
     service_rootwrap: rootwrap.d/vpnaas.filters