How to set up file-based logging in Symfony?

To set up file-based logging in Symfony, you'll need to follow these steps:

Install Monolog bundle: Monolog is the logging library used in Symfony, and it comes pre-installed with Symfony. However, you may need to install the Monolog bundle if it's not already installed in your project. You can do this by running the following command in your terminal:

composer require symfony/monolog-bundle

Configure Monolog in config.yml: Open your config.yml file and add the following configuration to enable file-based logging with Monolog:

monolog:
    handlers:
        file:
            type: stream
            path: "%kernel.logs_dir%/%kernel.environment%.log"
            level: debug

This configuration sets up a file handler that logs messages in the app/logs/ directory with the environment name (e.g., dev.log for the dev environment).

Add logger service to services.yml: To utilize the logger service in your application, you have to configure it in the services.yml file like so:

services:
    _defaults:
        autowire: true

    Psr\Log\LoggerInterface: '@monolog.logger'

This configuration sets up the LoggerInterface to use the Monolog logger service.

Start logging in your application: You can now start logging messages in your Symfony application by injecting the LoggerInterface service into your classes and using it to log messages as needed. For example:

// In a controller or service
use Psr\Log\LoggerInterface;

class MyController
{
    private $logger;

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

    public function index()
    {
        $this->logger->info('This is an info message');
        $this->logger->error('An error occurred');
        
        // Additional logging statements...
    }
}

With these steps, you have successfully set up file-based logging in Symfony using Monolog. You can now start logging messages to files in your application for debugging and monitoring purposes.