app/Config/Logger.php
<?php namespace Config;

use CodeIgniter\Config\BaseConfig;

class Logger extends BaseConfig
{
	/*
	|--------------------------------------------------------------------------
	| Error Logging Threshold
	|--------------------------------------------------------------------------
	|
	| You can enable error logging by setting a threshold over zero. The
	| threshold determines what gets logged. Any values below or equal to the
	| threshold will be logged. Threshold options are:
	|
	|	0 = Disables logging, Error logging TURNED OFF
	|	1 = Emergency Messages  - System is unusable
	|	2 = Alert Messages      - Action Must Be Taken Immediately
	|   3 = Critical Messages   - Application component unavailable, unexpected exception.
	|   4 = Runtime Errors      - Don't need immediate action, but should be monitored.
	|   5 = Warnings               - Exceptional occurrences that are not errors.
	|   6 = Notices            - Normal but significant events.
	|   7 = Info             - Interesting events, like user logging in, etc.
	|   8 = Debug                - Detailed debug information.
	|   9 = All Messages
	|
	| You can also pass an array with threshold levels to show individual error types
	|
	| 	array(1, 2, 3, 8) = Emergency, Alert, Critical, and Debug messages
	|
	| For a live site you'll usually enable Critical or higher (3) to be logged otherwise
	| your log files will fill up very fast.
	|
	*/
	public $threshold = 3;

	/*
	|--------------------------------------------------------------------------
	| Error Logging Directory Path
	|--------------------------------------------------------------------------
	| By default, logs are written to WRITEPATH . 'logs/'
	| Specify a different destination here, if desired.
	*/
	public $path = '';

	/*
	|--------------------------------------------------------------------------
	| Date Format for Logs
	|--------------------------------------------------------------------------
	|
	| Each item that is logged has an associated date. You can use PHP date
	| codes to set your own date formatting
	|
	*/
	public $dateFormat = 'Y-m-d H:i:s';

	/*
	|--------------------------------------------------------------------------
	| Log Handlers
	|--------------------------------------------------------------------------
	|
	| The logging system supports multiple actions to be taken when something
	| is logged. This is done by allowing for multiple Handlers, special classes
	| designed to write the log to their chosen destinations, whether that is
	| a file on the getServer, a cloud-based service, or even taking actions such
	| as emailing the dev team.
	|
	| Each handler is defined by the class name used for that handler, and it
	| MUST implement the CodeIgniter\Log\Handlers\HandlerInterface interface.
	|
	| The value of each key is an array of configuration items that are sent
	| to the constructor of each handler. The only required configuration item
	| is the 'handles' element, which must be an array of integer log levels.
	| This is most easily handled by using the constants defined in the
	| Psr\Log\LogLevel class.
	|
	| Handlers are executed in the order defined in this array, starting with
	| the handler on top and continuing down.
	|
	*/
	public $handlers = [

		//--------------------------------------------------------------------
		// File Handler
		//--------------------------------------------------------------------

		'CodeIgniter\Log\Handlers\FileHandler' => [

			/*
			 * The log levels that this handler will handle.
			 */
			'handles'         => [
				'critical',
				'alert',
				'emergency',
				'debug',
				'error',
				'info',
				'notice',
				'warning',
			],

			/*
			 * The default filename extension for log files.
			 * An extension of 'php' allows for protecting the log files via basic
			 * scripting, when they are to be stored under a publicly accessible directory.
			 *
			 * Note: Leaving it blank will default to 'log'.
			 */
			'fileExtension'   => '',

			/*
			 * The file system permissions to be applied on newly created log files.
			 *
			 * IMPORTANT: This MUST be an integer (no quotes) and you MUST use octal
			 * integer notation (i.e. 0700, 0644, etc.)
			 */
			'filePermissions' => 0644,
		],

		/**
		 * The ChromeLoggerHandler requires the use of the Chrome web browser
		 * and the ChromeLogger extension. Uncomment this block to use it.
		 */
		//      'CodeIgniter\Log\Handlers\ChromeLoggerHandler' => [
		//          /*
		//           * The log levels that this handler will handle.
		//           */
		//          'handles' => ['critical', 'alert', 'emergency', 'debug',
		//                        'error', 'info', 'notice', 'warning'],
		//      ]
	];
}
