How to Work with Compiler Passes
Compiler passes give you an opportunity to manipulate other service definitions that have been registered with the service container.
If your compiler pass is relatively small, you can define it inside the
application's Kernel class instead of creating a
separate compiler pass class.
To do so, make your kernel implement CompilerPassInterface
and add the compiler pass code inside the process() method:
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// src/Kernel.php
namespace App;
use Symfony\Bundle\FrameworkBundle\Kernel\MicroKernelTrait;
use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\HttpKernel\Kernel as BaseKernel;
class Kernel extends BaseKernel implements CompilerPassInterface
{
use MicroKernelTrait;
// ...
public function process(ContainerBuilder $container): void
{
// in this method you can manipulate the service container:
// for example, changing some container service:
$container->getDefinition('app.some_private_service')->setPublic(true);
// or processing tagged services:
foreach ($container->findTaggedServiceIds('some_tag') as $id => $tags) {
// ...
}
}
}If you create separate compiler pass classes, enable them in the build()
method of the application kernel:
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// src/Kernel.php
namespace App;
use App\DependencyInjection\Compiler\CustomPass;
use Symfony\Bundle\FrameworkBundle\Kernel\MicroKernelTrait;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\HttpKernel\Kernel as BaseKernel;
class Kernel extends BaseKernel
{
use MicroKernelTrait;
// ...
protected function build(ContainerBuilder $container): void
{
$container->addCompilerPass(new CustomPass());
}
}Working with Compiler Passes in Bundles
If your compiler pass is relatively small, you can add it directly in the main
bundle class. To do so, make your bundle implement the
CompilerPassInterface
and place the compiler pass code inside the process() method of the main
bundle class:
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// src/MyBundle/MyBundle.php
namespace App\MyBundle;
use App\DependencyInjection\Compiler\CustomPass;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\HttpKernel\Bundle\AbstractBundle;
class MyBundle extends AbstractBundle
{
public function process(ContainerBuilder $container): void
{
// in this method you can manipulate the service container:
// for example, changing some container service:
$container->getDefinition('app.some_private_service')->setPublic(true);
// or processing tagged services:
foreach ($container->findTaggedServiceIds('some_tag') as $id => $tags) {
// ...
}
}
}Alternatively, when using separate compiler pass classes,
bundles can enable them in the build() method of their main bundle class:
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// src/MyBundle/MyBundle.php
namespace App\MyBundle;
use App\DependencyInjection\Compiler\CustomPass;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\HttpKernel\Bundle\AbstractBundle;
class MyBundle extends AbstractBundle
{
public function build(ContainerBuilder $container): void
{
parent::build($container);
$container->addCompilerPass(new CustomPass());
}
}If you are using custom service tags in a
bundle, the convention is to format tag names by starting with the bundle's name
in lowercase (using underscores as separators), followed by a dot, and finally
the specific tag name. For example, to introduce a "transport" tag in your
AcmeMailerBundle, you would name it acme_mailer.transport.