How to Log Messages to different Files

How to Log Messages to different Files

The Symfony Framework organizes log messages into channels. By default, there are several channels, including doctrine, event, security, request and more. The channel is printed in the log message and can also be used to direct different channels to different places/files.

By default, Symfony logs every message into a single file (regardless of the channel).

Note

Each channel corresponds to a logger service (monolog.logger.XXX) in the container (use the debug:container command to see a full list) and those are injected into different services.

Switching a Channel to a different Handler

Now, suppose you want to log the security channel to a different file. To do this, just create a new handler and configure it to log only messages from the security channel. You might add this in config.yml to log in all environments, or just config_prod.yml to happen only in prod:

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    # app/config/config.yml
    monolog:
        handlers:
            security:
                # log all messages (since debug is the lowest level)
                level:    debug
                type:     stream
                path:     "%kernel.logs_dir%/security.log"
                channels: [security]
    
            # an example of *not* logging security channel messages for this handler
            main:
                # ...
                # channels: ["!security"]
    
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    <!-- app/config/config.xml -->
    <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"
    >
        <monolog:config>
            <monolog:handler name="security" type="stream" path="%kernel.logs_dir%/security.log">
                <monolog:channels>
                    <monolog:channel>security</monolog:channel>
                </monolog:channels>
            </monolog:handler>
    
            <monolog:handler name="main" type="stream" path="%kernel.logs_dir%/main.log">
                <!-- ... -->
                <monolog:channels>
                    <monolog:channel>!security</monolog:channel>
                </monolog:channels>
            </monolog:handler>
        </monolog:config>
    </container>
    
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    // app/config/config.php
    $container->loadFromExtension('monolog', array(
        'handlers' => array(
            'security' => array(
                'type'     => 'stream',
                'path'     => '%kernel.logs_dir%/security.log',
                'channels' => array(
                    'security',
                ),
            ),
            'main'     => array(
                // ...
                'channels' => array(
                    '!security',
                ),
            ),
        ),
    ));
    

YAML Specification

You can specify the configuration by many forms:

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channels: ~    # Include all the channels

channels: foo  # Include only channel "foo"
channels: "!foo" # Include all channels, except "foo"

channels: [foo, bar]   # Include only channels "foo" and "bar"
channels: ["!foo", "!bar"] # Include all channels, except "foo" and "bar"

Creating your own Channel

You can change the channel monolog logs to one service at a time. This is done either via the configuration below or by tagging your service with monolog.logger and specifying which channel the service should log to. With the tag, the logger that is injected into that service is preconfigured to use the channel you've specified.

Configure Additional Channels without Tagged Services

With MonologBundle 2.4 you can configure additional channels without the need to tag your services:

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    # app/config/config.yml
    monolog:
        channels: ["foo", "bar"]
    
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    <!-- app/config/config.xml -->
    <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"
    >
        <monolog:config>
            <monolog:channel>foo</monolog:channel>
            <monolog:channel>bar</monolog:channel>
        </monolog:config>
    </container>
    
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    // app/config/config.php
    $container->loadFromExtension('monolog', array(
        'channels' => array(
            'foo',
            'bar',
        ),
    ));
    

With this, you can now send log messages to the foo channel by using the automatically registered logger service monolog.logger.foo.

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