gitlab-ci-cd/general#3 Add support for docker image prefix to be able to load images from a proxy

src/Handler.php

@@ -32,7 +32,7 @@ class Handler extends BaseHandler {
    * {@inheritdoc}
    */
   protected function configDefault(): array {
-    $dockerImageProxy = $this->env->receiveGlobal('docker_image_prefix', '', '');
+    $dockerImageProxy = getenv('DOCKER_IMAGE_PREFIX');
     if (!empty($dockerImageProxy)) {
       $dockerImageProxy = str_replace('//', '/', $dockerImageProxy . '/');
     }