How to Add extra Data to Log Messages via a Processor
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How to Add extra Data to Log Messages via a Processor
Monolog allows you to process the record before logging it to add some extra data. A processor can be applied for the whole handler stack or only for a specific handler.
A processor is simply a callable receiving the record as its first argument.
Processors are configured using the monolog.processor DIC tag. See the
reference about it.
Adding a Session/Request Token
Sometimes it is hard to tell which entries in the log belong to which session and/or request. The following example will add a unique token for each request using a processor.
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namespace AppBundle\Logger;
use Symfony\Component\HttpFoundation\Session\SessionInterface;
class SessionRequestProcessor
{
private $session;
private $sessionId;
public function __construct(SessionInterface $session)
{
$this->session = $session;
}
public function processRecord(array $record)
{
if (!$this->session->isStarted()) {
return $record;
}
if (!$this->sessionId) {
$this->sessionId = substr($this->session->getId(), 0, 8) ?: '????????';
}
$record['extra']['token'] = $this->sessionId.'-'.substr(uniqid('', true), -8);
return $record;
}
}Next, register your class as a service, as well as a formatter that uses the extra information:
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# app/config/services.yml
services:
monolog.formatter.session_request:
class: Monolog\Formatter\LineFormatter
arguments:
- "[%%datetime%%] [%%extra.token%%] %%channel%%.%%level_name%%: %%message%% %%context%% %%extra%%\n"
AppBundle\Logger\SessionRequestProcessor:
autowire: true
tags:
- { name: monolog.processor, method: processRecord }Finally, set the formatter to be used on whatever handler you want:
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# app/config/config.yml
monolog:
handlers:
main:
type: stream
path: '%kernel.logs_dir%/%kernel.environment%.log'
level: debug
formatter: monolog.formatter.session_requestIf you use several handlers, you can also register a processor at the handler level or at the channel level instead of registering it globally (see the following sections).
Registering Processors per Handler
You can register a processor per handler using the handler option of
the monolog.processor tag:
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# app/config/config.yml
services:
AppBundle\Logger\SessionRequestProcessor:
autowire: true
tags:
- { name: monolog.processor, method: processRecord, handler: main }Registering Processors per Channel
You can register a processor per channel using the channel option of
the monolog.processor tag:
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# app/config/config.yml
services:
AppBundle\Logger\SessionRequestProcessor:
autowire: true
tags:
- { name: monolog.processor, method: processRecord, channel: main }
