diff -r d8a8c57f36c4 -r bf1bc6b08c46 dev/provisioning/modules/drush/manifests/install/composer.pp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dev/provisioning/modules/drush/manifests/install/composer.pp	Tue Oct 18 14:38:56 2016 +0200
@@ -0,0 +1,40 @@
+define drush::install::composer(
+  $autoupdate,
+  $version,
+  $install_path,
+  $install_type,
+) {
+
+  #private()
+  if $caller_module_name != $module_name {
+    warning("${name} is not part of the public API of the ${module_name} \
+module and should not be directly included in the manifest.")
+  }
+
+  # If version is 'master' or a single major release number,
+  # transform into something composer understands.
+  $real_version = $version ? {
+    /\./     => $version,
+    'master' => 'dev-master',
+    default  => "${version}.*",
+  }
+
+  file { $install_path:
+    ensure => directory,
+  }
+
+  $base_path = dirname($install_path)
+  $composer_home = "${base_path}/.composer"
+  $prefer = "--prefer-${install_type}"
+  $cmd = "${drush::composer_path} require drush/drush:${real_version} ${prefer}"
+  exec { $cmd:
+    cwd         => $install_path,
+    environment => ["COMPOSER_HOME=${composer_home}"],
+    require     => File[$install_path],
+  }
+  if ! $autoupdate {
+    Exec[$cmd] { creates => "${install_path}/composer.json"}
+  }
+
+}
+