Question

Is there a way to access the kernel from inside a compiler pass? I’ve tried this:

    ...
    public function process(ContainerBuilder $container)
    {
        $kernel = $container->get('kernel');
    }
    ...

This throws an error. Is there another way to do it?

Answer 1

As far as I can tell, Kernel isn’t available anywhere in a CompilerPass, by default.

But you can add it in by doing this:

In your AppKernel, pass $this to the bundle the compiler pass is in.

• Add a constructor to your Bundle object, which accepts the Kernel as a parameter and stores it as a property.
• In your Bundle::build() function, pass the Kernel to your CompilerPass instance.
• In your CompilerPass, at a constructor to accept the Kernel as a parameter and store it as a property.
• Then you can use $this->kernel in your compiler pass.

---

// app/AppKernel.php
new My\Bundle($this);

// My\Bundle\MyBundle.php
use Symfony\Component\HttpKernel\KernelInterface;

class MyBundle extends Bundle {
protected $kernel;

public function __construct(KernelInterface $kernel)
{
  $this->kernel = $kernel;
}

public function build(ContainerBuilder $container)
{
    parent::build($container);
    $container->addCompilerPass(new MyCompilerPass($this->kernel));
}

// My\Bundle\DependencyInjection\MyCompilerPass.php
use Symfony\Component\HttpKernel\KernelInterface;

class MyCompilerPass implements CompilerPassInterface
protected $kernel;

public function __construct(KernelInterface $kernel)
{
   $this->kernel = $kernel;
}

public function process(ContainerBuilder $container)
{
    // Do something with $this->kernel
}