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I have a module which subscribes to the kernel.request event to set some environment variables for use with LDAP. E.g. setting the LDAP_CACERT environment variable. I'm using it to replace hook_init() as recommended at https://www.drupal.org/node/2013014. However, I've noticed that it does not seem to set the environment variables at the start of Drush commands. E.g. I'd want the environment variables set in a PHP console or a cron run. This is part of a re-useable module so just adding it to settings.php is suboptimal.

What's the best way to execute code before any arbitrary Drush command runs?

I've found the console.command event which says:

The COMMAND event allows you to attach listeners before any command is executed by the console. It also allows you to modify the command, input and output before they are handled to the command.

I had hoped that would work with Drush 9. I've added it to my subscriber like so:

/**
  * {@inheritdoc}
  */
public static function getSubscribedEvents() {
  $events['kernel.request'] = ['setLdapEnvVariablesWeb'];
  $events['console.command'] = ['setLdapEnvVariablesCli'];
  return $events;
}

public function setLdapEnvVariablesCli(ConsoleCommandEvent $event) {
  $this->setLdapEnvVariables();
}

but unfortunately it never seems to be hit, even though I can see from drupal debug:event console.command that Drupal does recognize I am subscribed to it.

It would be nice if I could handle this in the same subscriber as for web requests but I am not set on it.

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  • What happens if you manually dispatch a console.command event? – Beau Dec 9 '20 at 13:31
  • @Beau It hits the callback as expected if I dispatch the event manually. – Dylan Dec 9 '20 at 14:42
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I've found out what's going on with this. It appears that Drush uses its own event dispatcher separate from Drupal's and that's where the console command event is actually dispatched. That means I need to manually add a listener to Drush's event dispatcher like so:

\Drush\Drush::service('eventDispatcher')->addListener('console.command', 'Drupal\mymodule\EventSubscriber\DefaultSubscriber::setLdapEnvVariablesCli');

Unfortunately there's still a problem: I need to add that subscriber somewhere that's called before the start of the command in order to be able to call things before the start of the command.

I ended up having to actually subscribe to the Drush event dispatcher event in settings.php:

if (function_exists('drush_main') && method_exists('Drush\Drush', 'service')) {
  \Drush\Drush::service('eventDispatcher')->addListener('console.command', 'Drupal\mymodule\EventSubscriber\DefaultSubscriber::setLdapEnvVariablesCli');
}

This isn't ideal but it does at least let me keep most of the actual logic in the subscriber.

then I made the CLI callback method and the common method static:

public static function setLdapEnvVariablesCli(ConsoleCommandEvent $event) {
  self::setLdapEnvVariables();
}

protected static function setLdapEnvVariables() {
  // ...
}

It's a bit ugly but it works. I'll just have to document that a settings.php change is needed in the module README.

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  • @Beau This actually isn't quite right yet. It's close but it only works immediately after a cache rebuild. So putting the listener in getSubscribedEvents() doesn't really work long term. I'll tweak it a bit once I've figured out a better way and then accept it. Plus it hasn't even been a day, in the meantime perhaps someone else will come along with a better answer. – Dylan Dec 9 '20 at 18:38
  • I have adjusted the answer with a solution that works long term. It does require a settings.php override unfortunately. – Dylan Dec 9 '20 at 21:56
  • 1
    That's not the worst thing in the world. Just a little extra documentation in your README. :) Nice job! – Beau Dec 10 '20 at 15:01

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