logger.rst

.. index::
    single: Console; Logger

Using the Logger

.. versionadded:: 2.5
    The :class:`Symfony\\Component\\Console\\Logger\\ConsoleLogger` was
    introduced in Symfony 2.5.

The Console component comes with a standalone logger complying with the PSR-3 standard. Depending on the verbosity setting, log messages will be sent to the :class:`Symfony\\Component\\Console\\Output\\OutputInterface` instance passed as a parameter to the constructor.

The logger does not have any external dependency except php-fig/log. This is useful for console applications and commands needing a lightweight PSR-3 compliant logger:

namespace Acme;

use Psr\Log\LoggerInterface;

class MyDependency
{
    private $logger;

    public function __construct(LoggerInterface $logger)
    {
        $this->logger = $logger;
    }

    public function doStuff()
    {
        $this->logger->info('I love Tony Vairelles\' hairdresser.');
    }
}

You can rely on the logger to use this dependency inside a command:

namespace Acme\Console\Command;

use Acme\MyDependency;
use Symfony\Component\Console\Command\Command;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Output\OutputInterface;
use Symfony\Component\Console\Logger\ConsoleLogger;

class MyCommand extends Command
{
    protected function configure()
    {
        $this
            ->setName('my:command')
            ->setDescription(
                'Use an external dependency requiring a PSR-3 logger'
            )
        ;
    }

    protected function execute(InputInterface $input, OutputInterface $output)
    {
        $logger = new ConsoleLogger($output);

        $myDependency = new MyDependency($logger);
        $myDependency->doStuff();
    }
}

The dependency will use the instance of :class:`Symfony\\Component\\Console\\Logger\\ConsoleLogger` as logger. Log messages emitted will be displayed on the console output.

Verbosity

Depending on the verbosity level that the command is run, messages may or may not be sent to the :class:`Symfony\\Component\\Console\\Output\\OutputInterface` instance.

By default, the console logger behaves like the :doc:`Monolog's Console Handler </cookbook/logging/monolog_console>`. The association between the log level and the verbosity can be configured through the second parameter of the :class:`Symfony\\Component\\Console\\ConsoleLogger` constructor:

// ...
$verbosityLevelMap = array(
    LogLevel::NOTICE => OutputInterface::VERBOSITY_NORMAL,
    LogLevel::INFO   => OutputInterface::VERBOSITY_NORMAL,
);
$logger = new ConsoleLogger($output, $verbosityLevelMap);

Color

The logger outputs the log messages formatted with a color reflecting their level. This behavior is configurable through the third parameter of the constructor:

// ...
$formatLevelMap = array(
    LogLevel::CRITICAL => self::INFO,
    LogLevel::DEBUG    => self::ERROR,
);
$logger = new ConsoleLogger($output, array(), $formatLevelMap);