The closest answer I saw was This One, but that's not what I need. 
Let's say I have the following array: 
$array = array (
    'docker-compose' => 
    array (
      'download_url' => '...',
    ),
    'darwin' => 
    array (
      'download_url' => '...',
    ),
    'linux' => 
    array (
      'download_url' => '....',
    ),
    'windows' => 
    array (
      'download_url' => '...',
    ),
    'debian' => 
    array (
      'download_url' => '...',
      'install_command' => '....',
    ),
    'rpm' => 
    array (
      'download_url' => '...',
      'install_command' => '...',
    ),
    'helm' => 
    array (
      'install_command' => '...',
      'wiki_url' => '',
    ),
    'docker' => 
    array (
      'install_command' => '....',
    ),
  )
And I want to sort it according to a simple logic that comes out from the following array:
$artifacts_importance_order = array(
    'helm',
    'rpm',
    'debian',
    'docker',
    'docker-compose',
    'linux',
    'windows',
    'darwin',
  );
If I was able to get the array's key inside usort() I'd do something like that:
usort($array, function($a, $b) use ($artifacts_importance_order){
  return (array_search(get_array_key($a),$artifacts_importance_order) < array_search(get_array_key($b),$artifacts_importance_order));  
});
Of course, get_array_key does not exist, but I'd like to know if there's something else I can do to get the key. 
The desired result will be:
  $array = array (
    'helm' => 
    array (
      'install_command' => '...',
      'wiki_url' => '',
    ),
    'rpm' => 
    array (
      'download_url' => '...',
      'install_command' => '...',
    ),
    'debian' => 
    array (
      'download_url' => '...',
      'install_command' => '....',
    ),
    'docker' => 
    array (
      'install_command' => '....',
    ),
    'docker-compose' => 
    array (
      'download_url' => '...',
    ),
    'linux' => 
    array (
      'download_url' => '....',
    ),
    'windows' => 
    array (
      'download_url' => '...',
    ),
    'darwin' => 
    array (
      'download_url' => '...',
    ),
  )
 
     
    