Inconsistent behavior with user_logout function

Question

For a drupal 8 site, I have a custom function that does the following:

It logs out the user and sends them to an external url

Inside the controller CustomController, I have:

function custom_logout(){
 if (\Drupal::currentUser()->isAuthenticated()) {
    user_logout();
    return new TrustedRedirectResponse('https://example.com');
 }
}

In the routing.yml

customl.clogout:
  path: '/customlogout'
  defaults:
    _controller: '\Drupal\user\Controller\CustomController::custom_logout'
  requirements:
    _user_is_logged_in: 'TRUE'
    

When I visit the /customlogout for the first time it logs me out of Drupal and redirects me to example.com. If I revisit my site and login in again, and repeat the process it still redirects me to example.com but when I check my site I am still logged in. I am wondering why this happens? I can still logout using /user/logout though

Thank you

Answer 1

As it turns out,

return new TrustedRedirectResponse('https://example.com');

was the culprit here. TrustedRedirectResponse extends CacheableSecuredRedirectResponse, as a result the function was cached, and user_logout was not called even when I visited the /customlogout

The workaround for this is adding the following lines in your routing.yml

options:
    
  no_cache: TRUE