src/DependencyInjection/ContainerInitializer/DefaultInitializer.php
public function initializeContainer(Application $application, array $extensions = array(), array $compilerPasses = array())
    {
        $container = $this->getContainerBuilder();
        $container->addObjectResource($application);
        $container->setParameter('app.env', $application->getEnvironment());
        $container->setParameter('app.debug', $application->isDebug());
        $container->setParameter('app.cache', $application->isCacheEnabled());
        $container->setParameter('app.root_dir', $application->getRootDir());
        $container->setParameter('app.cache_dir', $application->getCacheDir());
        $container->setParameter('app.log_dir', $application->getLogDir());

        $container->register('event_dispatcher', 'Symfony\Component\EventDispatcher\ContainerAwareEventDispatcher')
            ->setArguments(array(new Reference('service_container')));

        $container->register('app', 'Symfony\Component\HttpKernel\HttpKernelInterface')
            ->setSynthetic(true);

        $container->register('request', 'Symfony\Componenet\HttpKernel\Request')
            ->setSynthetic(true)
            ->setSynchronized(true)
            ->setScope('request');

        $container->addScope(new Scope('request'));

        $extensionAliases = array();
        foreach ($extensions as $extension) {
            $container->registerExtension($extension);
            $extensionAliases[] = $extension->getAlias();

            if ($extension instanceof CompilerAwareExtensionInterface) {
                $passes = $extension->getCompilerPasses();
                if (!is_array($passes)) {
                    $passes = array($passes);
                }

                $compilerPasses = array_merge($compilerPasses, $passes);
            }
        }

        $container->getCompilerPassConfig()->setMergePass(new MergeExtensionConfigurationPass($extensionAliases));
        $container->addCompilerPass(new RegisterListenersPass());

        foreach ($compilerPasses as $pass) {
            if (is_array($pass)) {
                $container->addCompilerPass($pass[0], $pass[1]);
            } else {
                $container->addCompilerPass($pass);
            }
        }

        $this->configProvider->load($container);

        $container->compile();

        return $container;
    }
public function initializeContainer(Application $application, array $extensions = array(), array $compilerPasses = array())
    {
        $container = $this->getContainerBuilder();
        $container->addObjectResource($application);
        $container->setParameter('app.env', $application->getEnvironment());
        $container->setParameter('app.debug', $application->isDebug());
        $container->setParameter('app.cache', $application->isCacheEnabled());
        $container->setParameter('app.root_dir', $application->getRootDir());
        $container->setParameter('app.cache_dir', $application->getCacheDir());
        $container->setParameter('app.log_dir', $application->getLogDir());

        $container->register('event_dispatcher', 'Symfony\Component\EventDispatcher\ContainerAwareEventDispatcher')
            ->setArguments(array(new Reference('service_container')));

        $container->register('app', 'Symfony\Component\HttpKernel\HttpKernelInterface')
            ->setSynthetic(true);

        $container->register('request', 'Symfony\Componenet\HttpKernel\Request')
            ->setSynthetic(true)
            ->setSynchronized(true)
            ->setScope('request');

        $container->addScope(new Scope('request'));

        $extensionAliases = array();
        foreach ($extensions as $extension) {
            $container->registerExtension($extension);
            $extensionAliases[] = $extension->getAlias();

            if ($extension instanceof CompilerAwareExtensionInterface) {
                $passes = $extension->getCompilerPasses();
                if (!is_array($passes)) {
                    $passes = array($passes);
                }

                $compilerPasses = array_merge($compilerPasses, $passes);
            }
        }

        $container->getCompilerPassConfig()->setMergePass(new MergeExtensionConfigurationPass($extensionAliases));
        $container->addCompilerPass(new RegisterListenersPass());

        foreach ($compilerPasses as $pass) {
            if (is_array($pass)) {
                $container->addCompilerPass($pass[0], $pass[1]);
            } else {
                $container->addCompilerPass($pass);
            }
        }

        $this->configProvider->load($container);

        $container->compile();

        return $container;
    }
Returns a fully built, ready to use Container

@param Application                   $application
@param array|ExtensionInterface[]    $extensions
@param array|CompilerPassInterface[] $compilerPasses

@return ContainerInterface