CakePHP Monolog Plugin (Addtion Datadog processor)

Despite the very advanced logging system offered in CakePHP, I still would have had to write a lot more code to be able to handle logs the way I needed. To write the least code possible, I chose to go with the popular monolog library.

DatadogProcessor append Datadog APM Trace ID and Span ID. This processor append the identifiers to all the log messages automatically. See: https://docs.datadoghq.com/tracing/advanced/connect_logs_and_traces/?tab=php

Install

Because monolog is a composer package and to avoid having to manually write a lot of includes (vs. auto-loading), I decided to release this also as a composer package and take advantage of the auto-loading magic.

First, add this plugin as a requirement to your composer.json

{
	"repositories": [
		{
			"type": "vcs",
			"url": "https://github.com/SNakano/cakephp-monolog"
		}
	],
	"require": {
		"snakano/monolog": "dev-master"
	}
}

And then update:

php composer.phar update

That's it! You should now be ready to start configuring your channels.

Configuration

Start by creating a logging configuration file (i.e. app/Config/log.php) that you will include early in your app/Config/bootstrap.php:

include 'log.php';

A basic configuration, to replicate what Cake does but using Monolog (to give you a good starting example), would look something like this:

require VENDORS . 'autoload.php';
App::build([
	'Plugin' => [ROOT . DS . 'Plugin' . DS]
]);

CakePlugin::load('Monolog');

CakeLog::config('debug', array(
	'engine' => 'Monolog.Monolog',
	'channel' => 'app',
	'handlers' => array(
		'Stream' => array(
			LOGS . 'debug.log',
			'formatters' => array(
				'Line' => array("%datetime% %channel% %level_name%: %message%\n")
			)
		)
	)
));

Note that with CakePHP versions < 2.4 the engine name should instead be Monolog.MonologLog.

Simple, no? But let's really do some serious logging, otherwise why bother moving away from the default CakePHP logging system?

The example below shows how to setup:

• rotating logs that are kept from 30 days and readable by logstash with memory peak usage info
• normal log file with much more details about the request
• email notifications for critical and alert levels including only the error message

CakeLog::config('logstash', array(
	'engine' => 'Monolog.Monolog',
	'channel' => 'app',
	'handlers' => array(
		'RotatingFile' => array(
			LOGS . 'application.log',
			30
		),
		'Stream' => array(
			LOGS . 'logstash.log',
			'formatters' => array(
				'Line' => array("%datetime% %channel% %level_name%: %message%\n")
			),
			'processors' => array(
				'DatadogProcessor' => array(
					'search' => CakePlugin::path('Monolog') . 'Lib' . DS . 'Log' . DS . 'Processor'
				),
				'MemoryUsage' => array(),
				'Web' => array()
			)
		),
		'CakeEmail' => array(
			'admin@domain.com',
			'ALERT: APPLICATION REQUIRES IMMEDIATE ATTENTION.',
			'default'
		)
	)
));