New in Symfony 7.2: Simpler Single-File Symfony Applications


Contributed by
Yonel Ceruto
in
#57408

Symfony allows you to create single-file applications which are useful for
simple workers, microservices, CLI tools, minimal APIs, and more. Here's an
example of a single-file application as it looks today:

// index.php
use App\Generator\NumberGenerator;
use Symfony\Bundle\FrameworkBundle\Kernel\MicroKernelTrait;
use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;
use Symfony\Component\HttpFoundation\JsonResponse;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpKernel\Kernel as BaseKernel;
use Symfony\Component\Routing\Attribute\Route;

require __DIR__.'/vendor/autoload.php';

class Kernel extends BaseKernel
{
use MicroKernelTrait;

public function registerBundles(): array
{
return [
new Symfony\Bundle\FrameworkBundle\FrameworkBundle(),
];
}

protected function configureContainer(ContainerConfigurator $container): void
{
$container->extension('framework', [
'secret' => 'S0ME_SECRET'
]);

// alternatively, define this in a configuration file and load it as:
// $container->import(__DIR__.'/../config/framework.yaml');
}

#[Route('/random/{limit}', name: 'random_number')]
public function randomNumber(int $limit, NumberGenerator $numberGenerator): JsonResponse
{
return new JsonResponse([
'number' => $numberGenerator->generate($limit),
]);
}
}

return static function (array $context) {
return new Kernel($context['APP_ENV'], (bool) $context['APP_DEBUG']);
}

In Symfony 7.2, we've simplified the MicroKernelTrait. Now, the same
application looks like this:

// index.php
use App\Generator\NumberGenerator;
use Symfony\Bundle\FrameworkBundle\Kernel\MicroKernelTrait;
use Symfony\Component\HttpFoundation\JsonResponse;
use Symfony\Component\HttpKernel\Kernel as BaseKernel;
use Symfony\Component\Routing\Attribute\Route;

require __DIR__.'/vendor/autoload.php';

class Kernel extends BaseKernel
{
use MicroKernelTrait;

#[Route('/random/{limit}', name: 'random_number')]
public function __invoke(int $limit, NumberGenerator $numberGenerator): JsonResponse
{
return new JsonResponse([
'number' => $numberGenerator->generate($limit),
]);
}
}

return static function (array $context) {
return new Kernel($context['APP_ENV'], (bool) $context['APP_DEBUG']);
}

The changes introduced in Symfony 7.2 are:

  • The config/ directory is now optional, so you can omit it entirely if you
    define the configuration in the configureContainer() method;
  • The bundles.php file is also optional and the registerBundles() method
    now defaults to yield new FrameworkBundle();. This removes the need to
    define that method when no other bundles are loaded;
  • Support for service injection in invokable actions using the __invoke() method;
  • The framework.secret parameter is now optional (related to a different
    pull request that will be covered in another blog post).

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