Enable neutron to work in a multi node setup

On the controller node where devstack is being run should create
the neutron network. The compute node should not.

The the case that we want to run a multi-node neutron setup we need
to configure the following (in the case that a plugin does not
have any agents running on the compute node):
ENABLED_SERVICES=n-cpu,neutron

In addition to this the code did not enable decomposed plugins to
configure their nova configurations if necessary.

This patch ensure that the multi-node support works.

Change-Id: I8e80edd453a1106ca666d6c531b2433be631bce4
Closes-bug: #1613069

lib/neutron

@@ -305,6 +305,9 @@ function configure_neutron_nova_new {
 
     iniset $NOVA_CONF DEFAULT firewall_driver nova.virt.firewall.NoopFirewallDriver
 
+    # optionally set options in nova_conf
+    neutron_plugin_create_nova_conf
+
     if is_service_enabled neutron-metadata-agent; then
         iniset $NOVA_CONF neutron service_metadata_proxy "True"
     fi

lib/neutron_plugins/services/l3

@@ -140,6 +140,14 @@ function _neutron_get_ext_gw_interface {
 }
 
 function create_neutron_initial_network {
+    if ! is_service_enabled q-svc && ! is_service_enabled neutron-api; then
+        echo "Controller services not enabled. No networks configured!"
+        return
+    fi
+    if [[ "$NEUTRON_CREATE_INITIAL_NETWORKS" == "False" ]]; then
+        echo "Network creation disabled!"
+        return
+    fi
     local project_id
     project_id=$(openstack project list | grep " demo " | get_field 1)
     die_if_not_set $LINENO project_id "Failure retrieving project_id for demo"

stack.sh

@@ -1248,10 +1248,7 @@ if is_service_enabled neutron; then
     start_neutron
 fi
 # Once neutron agents are started setup initial network elements
-if is_service_enabled q-svc && [[ "$NEUTRON_CREATE_INITIAL_NETWORKS" == "True" ]]; then
-    echo_summary "Creating initial neutron network elements"
-    create_neutron_initial_network
-fi
+create_neutron_initial_network
 
 if is_service_enabled nova; then
     echo_summary "Starting Nova"