afup/sources/AppBundle/Command/SynchTechLetterCommand.php

<?php

namespace AppBundle\Command;

use Symfony\Bundle\FrameworkBundle\Command\ContainerAwareCommand;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Output\OutputInterface;

class SynchTechLetterCommand extends ContainerAwareCommand
{
    /**
     * @see Command
     */
    protected function configure()
    {
        $this->setName('sync-techletter');
    }

    /**
     * @see Command
     */
    protected function execute(InputInterface $input, OutputInterface $output)
    {
        $container = $this->getContainer();

        $container
           ->get('app.techletter_mailchimp_synchronizer')
           ->setLogger($container->get('logger'))
           ->synchronize()
        ;
    }
}