NelmioCorsBundle is a Symfony bundle that adds support for CORS (Cross-Origin Resource Sharing) to your Symfony application. It allows you to configure and manage CORS headers easily, enabling secure cross-origin requests in your web applications.

Pros

• Easy integration with Symfony applications
• Highly configurable with support for path-based rules
• Supports preflight requests and caching
• Actively maintained and compatible with recent Symfony versions

Cons

• Limited to Symfony framework, not usable in other PHP projects
• May require additional configuration for complex CORS scenarios
• Performance impact when handling many CORS requests
• Learning curve for developers new to CORS concepts

Code Examples

1. Basic configuration in config/packages/nelmio_cors.yaml:

nelmio_cors:
    defaults:
        origin_regex: true
        allow_origin: ['%env(CORS_ALLOW_ORIGIN)%']
        allow_methods: ['GET', 'OPTIONS', 'POST', 'PUT', 'PATCH', 'DELETE']
        allow_headers: ['Content-Type', 'Authorization']
        expose_headers: ['Link']
        max_age: 3600

2. Path-specific configuration:

nelmio_cors:
    paths:
        '^/api/':
            allow_origin: ['http://example.com']
            allow_headers: ['X-Custom-Auth']
            allow_methods: ['POST', 'PUT', 'GET', 'DELETE']
            max_age: 3600

3. Configuring CORS in a controller using annotations:

use Nelmio\CorsBundle\Annotation\Cors;

/**
 * @Cors({"allow_origin": {"http://example.com"}, "allow_headers": {"X-Custom-Auth"}, "allow_methods": {"POST", "PUT", "GET", "DELETE"}})
 */
public function apiAction()
{
    // Your controller logic here
}

Getting Started

1. Install the bundle using Composer:

   composer require nelmio/cors-bundle
   

2. If you're using Symfony Flex, the bundle will be automatically configured. Otherwise, add it to your config/bundles.php:

   return [
       // ...
       Nelmio\CorsBundle\NelmioCorsBundle::class => ['all' => true],
   ];
   

3. Configure the bundle in config/packages/nelmio_cors.yaml (see the first code example for basic configuration).

4. Clear your cache:

   php bin/console cache:clear