AutoLogin.php

<?php

namespace AppBundle\Security\Authentication;

use AGILEmentBundle\Entity\User;
use Symfony\Component\Security\Core\Authentication\Token\Storage\TokenStorageInterface;
use Symfony\Component\Security\Core\Authentication\Token\UsernamePasswordToken;

class AutoLogin
{
    const FIREWALL_APP = 'main';

    private $tokenStorage;

    public function __construct(TokenStorageInterface $tokenStorage)
    {
        $this->tokenStorage = $tokenStorage;
    }

    public function login(User $user, $firewall = self::FIREWALL_APP)
    {
        $token = new UsernamePasswordToken($user, null, $firewall, $user->getRoles());
        $this->tokenStorage->setToken($token);
    }
}