Add a new parameter named cache_server_url

If you want to use horizon with a different cacheing backend you
may run into problems. E.g. with redis it expects a database after
the port.
So introducing a new parameter which allows any string as LOCATION
solves this problem and maybe a couple of others.

Change-Id: Ida54599049f69573d27f477c395f14ae0ec26c3c

manifests/init.pp

@@ -35,6 +35,11 @@
 #   (optional) A hash of parameters to enable specific cache options.
 #   Defaults to undef
 #
+#  [*cache_server_url*]
+#    (optional) URL of a cache server.
+#    This allows arbitary strings to be set as CACHE BACKEND LOCATION.
+#    Defaults to undef.
+#
 #  [*cache_server_ip*]
 #    (optional) Memcached IP address. Can be a string, or an array.
 #    Defaults to undef.
@@ -426,6 +431,7 @@ class horizon(
   $package_ensure                      = 'present',
   $cache_backend                       = 'django.core.cache.backends.locmem.LocMemCache',
   $cache_options                       = undef,
+  $cache_server_url                    = undef,
   $cache_server_ip                     = undef,
   $cache_server_port                   = '11211',
   $horizon_app_links                   = false,
@@ -498,6 +504,10 @@ class horizon(
 
   include ::horizon::deps
 
+  if $cache_server_url and $cache_server_ip {
+    fail('Only one of cache_server_url or cache_server_ip can be set.')
+  }
+
   $hypervisor_defaults = {
     'can_set_mount_point' => true,
     'can_set_password'    => false,

spec/classes/horizon_init_spec.rb

@@ -242,6 +242,23 @@ describe 'horizon' do
       it { is_expected.to contain_exec('refresh_horizon_django_compress') }
     end
 
+    context 'with overridden parameters and cache_server_url' do
+      before do
+        params.merge!({
+          :cache_server_url => 'redis://:password@10.0.0.1:6379/1',
+        })
+      end
+
+      it 'generates local_settings.py' do
+        verify_concat_fragment_contents(catalogue, 'local_settings.py', [
+          "        'LOCATION': 'redis://:password@10.0.0.1:6379/1',",
+        ])
+      end
+
+      it { is_expected.to contain_exec('refresh_horizon_django_cache') }
+      it { is_expected.to contain_exec('refresh_horizon_django_compress') }
+    end
+
     context 'installs python memcache library when cache_backend is set to memcache' do
       before do
         params.merge!({

templates/local_settings.py.erb

@@ -226,6 +226,9 @@ CACHES = {
         'LOCATION': '<%= @cache_server_ip %>:<%= @cache_server_port %>',
           <% end %>
     <% end %>
+    <% if @cache_server_url %>
+        'LOCATION': '<%= @cache_server_url %>',
+    <% end %>
     }
 }