cors.cache.php

<?php return array (
  '#^/oauth/v2/token$#s' => 
  array (
    'allow_methods' => 
    array (
      0 => 'GET',
      1 => 'POST',
    ),
  ),
  '#^/oauth/v2/auth$#s' => 
  array (
    'allow_methods' => 
    array (
      0 => 'GET',
      1 => 'POST',
    ),
  ),
);

CorsPathsCacheWarmer.php

<?php

namespace MyApp\ApiBundle\HttpKernel;

use JMS\DiExtraBundle\Annotation as DI;
use Symfony\Component\HttpKernel\CacheWarmer\CacheWarmer;
use Symfony\Component\HttpKernel\CacheWarmer\CacheWarmerInterface;
use Symfony\Component\Routing\RouterInterface;

/**
 * @DI\Service()
 * @DI\Tag("kernel.cache_warmer")
 */
class CorsPathsCacheWarmer extends CacheWarmer implements CacheWarmerInterface
{
    /**
     * @var RouterInterface
     */
    private $router;
    /**
     * @var array
     */
    private $config;

    /**
     * @DI\InjectParams({
     *     "router" = @DI\Inject("router"),
     *     "config" = @DI\Inject("%nelmio_cors.defaults%")
     * })
     *
     * @param RouterInterface $router
     * @param array           $config
     */
    public function __construct(RouterInterface $router, array $config)
    {
        $this->router = $router;
        $this->config = $config;
    }

    /**
     * {@inheritdoc}
     */
    public function isOptional()
    {
        return false;
    }

    /**
     * {@inheritdoc}
     */
    public function warmUp($cacheDir)
    {
        $paths = [];

        foreach ($this->router->getRouteCollection()->all() as $route) {
            $compiledRoute = $route->compile();

            $hostMatch = false;
            foreach ($this->config['hosts'] as $regex) {
                if (preg_match('{'.$regex.'}i', $route->getHost())) {
                    $hostMatch = true;
                    break;
                }
            }

            if (!$hostMatch) {
                continue;
            }

            $paths[$compiledRoute->getRegex()]['allow_methods'] = array_merge(
                isset($paths[$compiledRoute->getRegex()]['allow_methods'])
                    ? $paths[$compiledRoute->getRegex()]['allow_methods']
                    : [],
                $route->getMethods()
            );
        }

        $this->writeCacheFile($cacheDir . '/cors.cache.php', '<?php return ' . var_export($paths, true) . ';');
    }
}

RouterBasedConfigProvider.php

<?php

namespace MyApp\ApiBundle\Service;

use JMS\DiExtraBundle\Annotation as DI;
use Nelmio\CorsBundle\Options\ProviderInterface;
use Symfony\Component\HttpFoundation\Request;

/**
 * @DI\Service()
 * @DI\Tag("nelmio_cors.options_provider", attributes={ "priority": 1 })
 */
class RouterBasedConfigProvider implements ProviderInterface
{
    protected $paths;
    protected $defaults;

    /**
     * @DI\InjectParams({
     *     "cacheDir" = @DI\Inject("%kernel.cache_dir%")
     * })
     */
    public function __construct($cacheDir)
    {
        $this->paths = include $cacheDir . '/cors.cache.php';
    }

    /**
     * {@inheritdoc}
     */
    public function getOptions(Request $request)
    {
        $uri = $request->getPathInfo() ?: '/';
        foreach ($this->paths as $pathRegexp => $options) {
            if (preg_match($pathRegexp, $uri)) {
                return $options;
            }
        }

        return [];
    }
}