How to Define a Custom Logging Formatter

Warning: You are browsing the documentation for Symfony 4.0, which is no longer maintained.

Read the updated version of this page for Symfony 6.1 (the current stable version).

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 easily. 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:

YAML
XML
PHP

        1
2
3
4
5
6
7
8
9
10
11
12
13
        # config/services.yaml
services:
    # ...

    Monolog\Formatter\JsonFormatter: ~

# config/packages/prod/monolog.yaml (and/or config/packages/dev/monolog.yaml)
monolog:
    handlers:
        file:
            type: stream
            level: debug
            formatter: Monolog\Formatter\JsonFormatter
    

        1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
        <!-- 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
        http://symfony.com/schema/dic/services/services-1.0.xsd
        http://symfony.com/schema/dic/monolog
        http://symfony.com/schema/dic/monolog/monolog-1.0.xsd">

    <services>
        <service id="Monolog\Formatter\JsonFormatter" />
    </services>

    <!-- 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\JsonFormatter"
        />
    </monolog:config>
</container>
    

        1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
        // config/services.php
use Monolog\Formatter\JsonFormatter;

$container->register(JsonFormatter::class);

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