Provide a mechanism for a UI-only user to clear the cache if Drupal is unavailable

I think that, in Drupal CMS, we could add a drush cr as a post-update-cmd Composer script.

In addition to #3, we can also put the cache clear block (provided by core) into the dashboard, so users don't have to go digging around for it.

@catch directed me to 📌 Use a better container cache key Active , which would also greatly mitigate this problem.

chatted w/ phenaproxima and I understand the problem, now.

Sometimes after running an update, the cache becomes corrupted and has to be cleared.

This confused me. It's not _update_ as in Drupal database updates but dependency updates. A module is update which has modified it's service constructors. Drupal is still using a previous container cache for the previous version of the module. When the user goes to their Drupal site, the container constructs the services using previous arguments and we WSOD.

📌 Use a better container cache key Active solves this by using dependency version information to vary the container cache. So I think Drupal CMS can provide a Composer script which _kind of_ does the same thing. Without calling `drupal_rebuild`. When calling `drupal_rebuild` all caches get destroyed, which can be bad ahead of actually running updates.

Instead it should have a script which does clears the container cache only. This can be done via drush cc container or a PHP script like:

$autoloader = require_once __DIR__ . '/autoload.php';
$request = Request::createFromGlobals();
$kernel = new DrupalKernel('prod', $class_loader);
$kernel->setSitePath(DrupalKernel::findSitePath($request));
$kernel->invalidateContainer();

@mglaman updated the IS to clarify that yes it's composer updates rather than db updates!