Write a Composer warning message when upgrading from < 5.0.0

composer/src/Plugin.php

@@ -57,9 +57,34 @@ public function addVagrantfile(Event $event) {
 
  if (file_exists($source)) {
  if (!file_exists($target) || md5_file($source) != md5_file($target)) {
+ $isLegacy = $this->isLegacyVagrantfile($target);
+
  copy($source, $target);
+
+ $extra = $this->composer->getPackage()->getExtra();
+ if ($isLegacy && !isset($extra['drupalvm']['config_dir'])) {
+ $this->io->writeError(
+ '<warning>'
+ . 'Drupal VM has been updated and consequently written over your Vagrantfile which from now on will be managed by Drupal VM. '
+ . 'Due to this change, you are required to set your `config_dir` location in your composer.json file. Below follows the necessary change:'
+ . '</warning>'
+ );
+ $this->io->writeError('');
+ $this->io->writeError(json_encode(['extra' => ['drupalvm' => ['config_dir' => '<sub-directory>']]], JSON_PRETTY_PRINT));
+ }
  }
  }
  }
 
+ /**
+ * Return if the parent project is using the < 5.0.0 delegating Vagrantfile.
+ *
+ * @return bool
+ */
+ private function isLegacyVagrantfile($vagrantfile) {
+ if (!file_exists($vagrantfile)) {
+ return false;
+ }
+ return strpos(file_get_contents($vagrantfile), '# Load the real Vagrantfile') !== FALSE;
+ }
 }