I’m trying to implement the Background Image module, but there seems to be a problem with the dynamic route it registers for generating CSS. I’ve been debugging it but have run into a wall. It’s basically a duplicate of the core Image module’s routing setup, so I’m not sure what’s wrong, but the controller method never fires – the controller isn’t even instantiated. Here’s the config file:

route_callbacks:   - '\Drupal\background_image\Routing\BackgroundImageRoutes::routes' 

Here’s the routes method:

  public function routes() {     error_log('Router::routes');     $  routes = [];     // Generate background image CSS files. If clean URLs are disabled the     // files will always be served through the menu system. If clean URLs are     // enabled and the file already exists, PHP will be bypassed.     $  directory_path = $  this->streamWrapperManager->getViaScheme('public')->getDirectoryPath();      $  routes['background_image.css'] = new Route(       '/' . $  directory_path . '/background_image/css/{background_image}/{scheme}/{file}',       [         '_controller' => '\Drupal\background_image\Controller\BackgroundImageCssController::deliver',       ],       [         '_access' => 'TRUE',       ]     );     error_log(print_r($  routes, true));     return $  routes;   } 

Here’s the $ routes object:

Array (     [background_image.css] => Symfony\Component\Routing\Route Object         (             [path:Symfony\Component\Routing\Route:private] => /sites/default/files/background_image/css/{background_image}/{scheme}/{file}             [host:Symfony\Component\Routing\Route:private] =>              [schemes:Symfony\Component\Routing\Route:private] => Array                 (                 )             [methods:Symfony\Component\Routing\Route:private] => Array                 (                 )             [defaults:Symfony\Component\Routing\Route:private] => Array                 (                     [_controller] => \Drupal\background_image\Controller\BackgroundImageCssController::deliver                 )             [requirements:Symfony\Component\Routing\Route:private] => Array                 (                     [_access] => TRUE                 )             [options:Symfony\Component\Routing\Route:private] => Array                 (                     [compiler_class] => Symfony\Component\Routing\RouteCompiler                 )             [compiled:Symfony\Component\Routing\Route:private] =>              [condition:Symfony\Component\Routing\Route:private] =>          ) ) 

If I try to hit a URL such as /sites/default/files/background_image/css/3/public/dq5DbF1hqHxkHXGiHSl9yuXubPox08bOX6nE12gX2h0.css?p2aptq (which the module correctly generates when I’ve got a background image set up on the site) I get a 404 error and nothing in the error log.

I’m using docker4drupal and have checked the nginx config and am 99% sure that’s not the issue (there are no rules for /sites/default/files/ and I do see the 404 in the nginx log.)