formatter.rst

How to Define a Custom Logging Formatter

Each logging handler uses a Formatter to format the record before logging it. All Monolog handlers use an instance of Monolog\Formatter\LineFormatter by default but you can replace it. Your formatter must implement Monolog\Formatter\FormatterInterface.

For example, to use the built-in JsonFormatter, register it as a service then configure your handler to use it:

.. configuration-block::

    .. code-block:: yaml

        # config/packages/prod/monolog.yaml (and/or config/packages/dev/monolog.yaml)
        monolog:
            handlers:
                file:
                    type: stream
                    level: debug
                    formatter: 'monolog.formatter.json'

    .. code-block:: xml

        <!-- config/services.xml -->
        <?xml version="1.0" encoding="UTF-8" ?>
        <container xmlns="http://symfony.com/schema/dic/services"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xmlns:monolog="http://symfony.com/schema/dic/monolog"
            xsi:schemaLocation="http://symfony.com/schema/dic/services
                https://symfony.com/schema/dic/services/services-1.0.xsd
                http://symfony.com/schema/dic/monolog
                https://symfony.com/schema/dic/monolog/monolog-1.0.xsd">

            <!-- config/packages/prod/monolog.xml (and/or config/packages/dev/monolog.xml) -->
            <monolog:config>
                <monolog:handler
                    name="file"
                    type="stream"
                    level="debug"
                    formatter="monolog.formatter.json"
                />
            </monolog:config>
        </container>

    .. code-block:: php

        // config/services.php
        use Monolog\Formatter\JsonFormatter;

        // config/packages/prod/monolog.php (and/or config/packages/dev/monolog.php)
        $container->loadFromExtension('monolog', [
            'handlers' => [
                'file' => [
                    'type'      => 'stream',
                    'level'     => 'debug',
                    'formatter' => 'monolog.formatter.json',
                ],
            ],
        ]);