Default neutron dhcp_agents_per_network to number of agents

This patch will set neutron's dhcp_agents_per_network equal to the
number of deployed neutron DHCP agents unless otherwise explicitly set.

Partial-bug: #1632721
Change-Id: I5533e42c5ba9f72cc70d80489a07e30ee2341198

manifests/profile/base/neutron.pp

@@ -65,6 +65,19 @@
 # [*oslomsg_use_ssl*]
 #   Enable ssl oslo messaging services
 #   Defaults to hiera('neutron::rabbit_use_ssl', '0')
+#
+# [*dhcp_agents_per_network*]
+#   (Optional) TripleO configured number of DHCP agents
+#   to use per network. If left to the default value, neutron will be
+#   configured with the number of DHCP agents being deployed.
+#   Defaults to undef
+#
+# [*dhcp_nodes*]
+#   (Optional) List of nodes running the DHCP agent. Used to
+#   set neutron's dhcp_agents_per_network value to the number
+#   of available agents.
+#   Defaults to hiera('neutron_dhcp_short_node_names') or []
+#
 
 class tripleo::profile::base::neutron (
   $step                    = hiera('step'),
@@ -79,9 +92,23 @@ class tripleo::profile::base::neutron (
   $oslomsg_notify_port     = hiera('neutron::rabbit_port', '5672'),
   $oslomsg_notify_username = hiera('neutron::rabbit_userid', 'guest'),
   $oslomsg_use_ssl         = hiera('neutron::rabbit_use_ssl', '0'),
+  $dhcp_agents_per_network = undef,
+  $dhcp_nodes              = hiera('neutron_dhcp_short_node_names', []),
 ) {
   if $step >= 3 {
     $oslomsg_use_ssl_real = sprintf('%s', bool2num(str2bool($oslomsg_use_ssl)))
+
+    $dhcp_agent_count = size($dhcp_nodes)
+    if $dhcp_agents_per_network {
+      $dhcp_agents_per_net = $dhcp_agents_per_network
+      if ($dhcp_agents_per_net > $dhcp_agent_count) {
+        warning("dhcp_agents_per_network (${dhcp_agents_per_net}) is greater\
+ than the number of deployed dhcp agents (${dhcp_agent_count})")
+      }
+    }
+    elsif $dhcp_agent_count > 0 {
+      $dhcp_agents_per_net = $dhcp_agent_count
+    }
     class { '::neutron' :
       default_transport_url      => os_transport_url({
         'transport' => $oslomsg_rpc_proto,
@@ -99,6 +126,7 @@ class tripleo::profile::base::neutron (
         'password'  => $oslomsg_notify_password,
         'ssl'       => $oslomsg_use_ssl_real,
       }),
+      dhcp_agents_per_network    => $dhcp_agents_per_net,
     }
     include ::neutron::config
   }

releasenotes/notes/calculate-dhcp-agents-per-network-3089c5e7b15f8b7b.yaml

@@ -0,0 +1,5 @@
+---
+features: |
+  - Unless a non-default value is provided, the dhcp_agents_per_network
+    neutron configuration variable is set to the number of deployed
+    neutron dhcp agents.

spec/classes/tripleo_profile_base_neutron_spec.rb

@@ -0,0 +1,76 @@
+#
+# Copyright (C) 2016 Red Hat, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+
+require 'spec_helper'
+
+describe 'tripleo::profile::base::neutron' do
+  let :params do
+    { :step                    => 5,
+      :oslomsg_notify_password => 'foobar',
+      :oslomsg_rpc_password    => 'foobar'
+    }
+  end
+
+  shared_examples_for 'tripleo::profile::base::neutron' do
+    before :each do
+      facts.merge!({ :step => params[:step] })
+    end
+
+    context 'when no dhcp agents per network set' do
+      before do
+        params.merge!({
+          :dhcp_nodes => ['netcont1.localdomain', 'netcont2.localdomain', 'netcont3.localdomain']
+        })
+      end
+      it 'should equal the number of dhcp agents' do
+        is_expected.to contain_class('neutron').with(:dhcp_agents_per_network => 3)
+      end
+    end
+
+    context 'when dhcp agents per network is set' do
+      before do
+        params.merge!({
+          :dhcp_agents_per_network => 2
+        })
+      end
+      it 'should set the the value' do
+        is_expected.to contain_class('neutron').with(:dhcp_agents_per_network => 2)
+      end
+    end
+
+    context 'when dhcp agents per network is greater than number of agents' do
+      before do
+        params.merge!({
+          :dhcp_nodes => ['netcont1.localdomain', 'netcont2.localdomain'],
+          :dhcp_agents_per_network => 5
+        })
+      end
+      it 'should set value and complain about not enough agents' do
+        is_expected.to contain_class('neutron').with(:dhcp_agents_per_network => 5)
+      end
+    end
+  end
+
+  on_supported_os.each do |os, facts|
+    context "on #{os}" do
+      let(:facts) do
+        facts.merge({ :hostname => 'node.example.com' })
+      end
+
+      it_behaves_like 'tripleo::profile::base::neutron'
+    end
+  end
+end