Message: SQLSTATE[HY000] [2002] php_network_getaddresses: getaddrinfo failed: Name or service not known

Trace: #0 /var/www/html/vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOConnection.php(36): PDO->__construct('mysql:host=db;d...', 'db', 'db', Array)
#1 /var/www/html/vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOMySql/Driver.php(47): Doctrine\DBAL\Driver\PDOConnection->__construct('mysql:host=db;d...', 'db', 'db', Array)
#2 /var/www/html/vendor/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(350): Doctrine\DBAL\Driver\PDOMySql\Driver->connect(Array, 'db', 'db', Array)
#3 /var/www/html/vendor/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(949): Doctrine\DBAL\Connection->connect()
#4 /var/www/html/vendor/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php(313): Doctrine\DBAL\Connection->beginTransaction()
#5 /var/www/html/vendor/doctrine/orm/lib/Doctrine/ORM/EntityManager.php(355): Doctrine\ORM\UnitOfWork->commit(NULL)
#6 /var/www/html/src/Langify/Bundle/AppBundle/Controller/InstallController.php(39): Doctrine\ORM\EntityManager->flush()
#7 [internal function]: Langify\Bundle\AppBundle\Controller\InstallController->indexAction(Object(Symfony\Component\HttpFoundation\Request))
#8 /var/www/html/app/bootstrap.php.cache(2841): call_user_func_array(Array, Array)
#9 /var/www/html/app/bootstrap.php.cache(2815): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1)
#10 /var/www/html/app/bootstrap.php.cache(2944): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#11 /var/www/html/app/bootstrap.php.cache(2245): Symfony\Component\HttpKernel\DependencyInjection\ContainerAwareHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#12 /var/www/html/web/app_dev.php(23): Symfony\Component\HttpKernel\Kernel->handle(Object(Symfony\Component\HttpFoundation\Request))
#13 {main}