Add support for running Zuul on Trusty

Puppet install zuul on Ubuntu 14.04 Trusty fails because Apache/2.4.7
does not have mod_mem_cache. According to [1], we should use
 mod_cache_disk instead.

"These modules have been removed: mod_authn_default, mod_authz_default,
 mod_mem_cache. If you were using mod_mem_cache in 2.2,
 look at mod_cache_disk in 2.4."

Add configuration to cache /status.json using mod_cache_disk.

Allow access to the 'DocumentRoot' path, which is disallowed on 14.04
by default.

[1] http://httpd.apache.org/docs/trunk/upgrading.html

Change-Id: I734b5c45e1e088364328e9fc5ec5932d3bfe32c5

modules/zuul/manifests/init.pp

@@ -347,9 +347,22 @@ class zuul (
       ensure => present,
     }
   }
-  if ! defined(A2mod['mem_cache']) {
-    a2mod { 'mem_cache':
-      ensure => present,
+
+  case $::lsbdistcodename {
+    'precise': {
+      if ! defined(A2mod['mem_cache']) {
+        a2mod { 'mem_cache':
+          ensure => present,
+        }
+      }
+    }
+    default: {
+      if ! defined(A2mod['cache_disk']) {
+        a2mod { 'cache_disk':
+          ensure => present,
+        }
+      }
     }
   }
+
 }

modules/zuul/templates/zuul.vhost.erb

@@ -2,6 +2,11 @@
   ServerAdmin <%= scope.lookupvar("::zuul::serveradmin") %>
   DocumentRoot /var/lib/zuul/www
 
+  <Directory /var/lib/zuul/www>
+    Allow from all
+    Satisfy Any
+  </Directory>
+
   ErrorLog ${APACHE_LOG_DIR}/<%= scope.lookupvar("::zuul::vhost_name") %>-error.log
 
   LogLevel warn
@@ -32,6 +37,10 @@
       MCacheMaxObjectSize 8388608
       MCacheMaxStreamingBuffer 8388608
     </IfModule>
+    <IfModule mod_cache_disk.c>
+      CacheEnable disk /status.json
+      CacheRoot /var/cache/apache2/mod_cache_disk
+    </IfModule>
   </IfModule>
 
 </VirtualHost>