Add manage_memcache_package parameter

Adds a new parameter named manage_memcache_package that
can be used to set if we should install the python memcache
library if memcache caching is enabled.

Change-Id: I924f837afc756817c202637b1b7db83c125df1d8

manifests/init.pp

@@ -47,6 +47,10 @@
 #  [*cache_server_port*]
 #    (optional) Memcached port. Defaults to '11211'.
 #
+#  [*manage_memcache_package*]
+#    (optional) Boolean if we should manage the memcache package.
+#    Defaults to true
+#
 #  [*horizon_app_links*]
 #    (optional) Array of arrays that can be used to add call-out links
 #    to the dashboard for other apps. There is no specific requirement
@@ -459,6 +463,7 @@ class horizon(
   $cache_server_url                    = undef,
   $cache_server_ip                     = undef,
   $cache_server_port                   = '11211',
+  $manage_memcache_package             = true,
   $horizon_app_links                   = false,
   $keystone_url                        = 'http://127.0.0.1:5000',
   $keystone_default_role               = '_member_',
@@ -601,7 +606,7 @@ class horizon(
   validate_re($images_panel, ['^legacy$', '^angular$'])
   validate_absolute_path($root_path)
 
-  if $cache_backend =~ /MemcachedCache/ {
+  if $manage_memcache_package and $cache_backend =~ /MemcachedCache/ {
     ensure_resources('package', { 'python-memcache' =>
       { name   => $::horizon::params::memcache_package,
         tag    => ['openstack', 'horizon-package']}})

releasenotes/notes/manage-memcache-param-4fbc465b88b062db.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Added a new parameter horizon::manage_memcache_package that can be used to
+    determine if you want the python memcache library installed if the cache
+    backend is set to using memcache.

spec/classes/horizon_init_spec.rb

@@ -280,6 +280,15 @@ describe 'horizon' do
       }
     end
 
+    context 'does not install python memcache when manage_memcache_package set to false' do
+      before do
+        params.merge!( :cache_backend           => 'django.core.cache.backends.memcached.MemcachedCache',
+                       :manage_memcache_package => false )
+      end
+
+      it { is_expected.not_to contain_package('python-memcache') }
+    end
+
     context 'with custom wsgi options' do
       before do
         params.merge!( :wsgi_processes => '30',