diff -r d8a8c57f36c4 -r bf1bc6b08c46 dev/provisioning/modules/drush/manifests/extension.pp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dev/provisioning/modules/drush/manifests/extension.pp	Tue Oct 18 14:38:56 2016 +0200
@@ -0,0 +1,17 @@
+define drush::extension() {
+
+  if (!defined(Class['drush'])) {
+    fail('You must include class drush before declaring aliases')
+  }
+
+  # Split $name at the dash to eliminate the version component.
+  $parts = split($name, '-')
+  $extension_name = $parts[0]
+
+  exec {"${drush::drush_exe_default} dl ${name}":
+    command => "/usr/bin/su - -c '${drush::drush_exe_default} dl ${name}'",
+    creates => "/usr/share/drush/commands/${extension_name}",
+    notify  => Class['drush::cacheclear'],
+  }
+
+}