Issue #3262296 by MacSim, danflanagan8, apaderno: Get rid of the API key file...

<?php

namespace Drupal\index_now\Controller;

use Drupal\Core\Cache\CacheableResponse;

use Drupal\Core\Controller\ControllerBase;

use Drupal\Core\State\StateInterface;

use Symfony\Component\DependencyInjection\ContainerInterface;

use Symfony\Component\HttpFoundation\Response;

use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;

/**

 * API key controller.

 */

class ApiKeyController extends ControllerBase {

  /**

   * API key controller constructor.

   *

   * @param \Drupal\Core\State\StateInterface $state

   *   The state service.

   */

  public function __construct(StateInterface $state) {

    $this->state = $state;

  }

  /**

   * {@inheritdoc}

   */

  public static function create(ContainerInterface $container) {

    return new static(

      $container->get('state')

    );

  }

  /**

   * Render the API key.

   *

   * @param string $api_key

   *   A string representing the api key.

   */

  public function build(string $api_key) {

    $state_api_key = $this->state->get('index_now_api_key');

    if (empty($state_api_key) || $state_api_key !== $api_key) {

      throw new NotFoundHttpException();

    }

    $response = new CacheableResponse($api_key, Response::HTTP_OK, ['content-type' => 'text/plain']);

    $metadata = $response->getCacheableMetadata();

    $metadata->addCacheTags(['state:index_now_api_key']);

    return $response;

  }

}

<?php

namespace Drupal\index_now\PathProcessor;

use Drupal\Core\PathProcessor\InboundPathProcessorInterface;

use Drupal\Core\State\StateInterface;

use Symfony\Component\HttpFoundation\Request;

/**

 * Index Now path processor.

 */

class IndexNowPathProcessor implements InboundPathProcessorInterface {

  /**

   * The state service.

   *

   * @var \Drupal\Core\State\StateInterface

   */

  protected $state;

  /**

   * Class constructor.

   *

   * @param \Drupal\Core\State\StateInterface $state

   *   The state service.

   */

  public function __construct(StateInterface $state) {

    $this->state = $state;

  }

  /**

   * {@inheritdoc}

   */

  public function processInbound($path, Request $request) {

    $api_key = $this->state->get('index_now_api_key');

    if (!empty($api_key) && '/index_now_api_key_' . $api_key . '.txt' === $path) {

      return '/index_now_api_key/' . $api_key;

    }

    return $path;

  }

}