Move cache directory out of mediawiki Git worktree

For improved sanitation, have the application write its cache files
in a directory parallel to the Git worktree rather than inside it.

Change-Id: Idcfcf0e3709a03696966aa8c27b897d5be7a1970

manifests/app.pp

@@ -7,13 +7,6 @@ class mediawiki::app ($revision = 'origin/REL1_28'){
     source   => 'https://gerrit.wikimedia.org/r/mediawiki/core.git',
     revision => $revision,
   }
-  file { '/srv/mediawiki/w/cache':
-    ensure  => directory,
-    recurse => true,
-    owner   => 'www-data',
-    group   => 'www-data',
-    require => Vcsrepo['/srv/mediawiki/w'],
-  }
 }
 
 # vim:sw=2:ts=2:expandtab:textwidth=79

manifests/init.pp

@@ -2,6 +2,7 @@
 #
 class mediawiki(
   $mediawiki_location         = '/srv/mediawiki/w',
+  $mediawiki_cache_location   = '/srv/mediawiki/cache',
   $mediawiki_images_location  = '/srv/mediawiki-data/images',
   $role                       = 'all',
   $site_hostname              = $::fqdn,
@@ -39,6 +40,14 @@ class mediawiki(
       ensure => directory,
     }
 
+    file { $mediawiki_cache_location:
+      ensure  => directory,
+      recurse => true,
+      owner   => 'www-data',
+      group   => 'www-data',
+      require => File['/srv/mediawiki'],
+    }
+
     file { '/srv/mediawiki-data':
       ensure => directory,
     }

templates/Settings.php.erb

@@ -64,7 +64,7 @@ $wgShowIPinHeader = false;
 
 $wgDisableCounters = true;
 
-$wgCacheDirectory = "$IP/cache";
+$wgCacheDirectory = "<%= @mediawiki_cache_location %>";
 
 # New-style Object cache (and session) settings
 $wgObjectCaches['memcached-pecl'] = array(