PHP log collection

Use Composer to add Monolog as a dependency:

composer require "monolog/monolog"

Alternatively, install it manually:

1. Download Monolog from the repository and include it to the libraries

2. Initialize the instance in the application’s bootstrap

   <?php
     require __DIR__ . '/vendor/autoload.php';
   
     // load Monolog library
     use Monolog\Logger;
     use Monolog\Handler\StreamHandler;
     use Monolog\Formatter\JsonFormatter;
   

Zend-log is a part of the Zend framework. Use Composer to add Zend-Log:

composer require "zendframework/zend-log"

Alternatively, install it manually:

1. Download the source from the repository and include it to the libraries
2. Initialize the instance in the application’s bootstrap

<?php
  require __DIR__ . '/vendor/autoload.php';

  use Zend\Log\Logger;
  use Zend\Log\Writer\Stream;
  use Zend\Log\Formatter\JsonFormatter;

Declare a Monolog JSON formatter as a service:

services:
    monolog.json_formatter:
        class: Monolog\Formatter\JsonFormatter

The following configuration enables the JSON formatting and writes the logs and events into the application-json.log file. Edit your code, right after the initialization of the Monolog instance and add a new handler:

 <?php
  require __DIR__ . '/vendor/autoload.php';

  // load Monolog library
  use Monolog\Logger;
  use Monolog\Handler\StreamHandler;
  use Monolog\Formatter\JsonFormatter;

  // create a log channel
  $log = new Logger('channel_name');

  // create a Json formatter
  $formatter = new JsonFormatter();

  // create a handler
  $stream = new StreamHandler(__DIR__.'/application-json.log', Logger::DEBUG);
  $stream->setFormatter($formatter);

  // bind
  $log->pushHandler($stream);

  // an example
  $log->info('Adding a new user', array('username' => 'Seldaek'));

The following configuration enables the JSON formatting and writes the logs and events into the application-json.log file. Edit your code, right after the initialization of the Zend-Log instance and add a new handler.

<?php
  use Zend\Log\Logger;
  use Zend\Log\Writer\Stream;
  use Zend\Log\Formatter\JsonFormatter;

  // create a logger
  $logger = new Logger();

  // create a writer
  $writer = new Stream('file://' . __DIR__ . '/application-json.log');

  // create a Json formatter
  $formatter = new JsonFormatter();
  $writer->setFormatter($formatter);

  // bind
  $logger->addWriter($writer);
  Zend\Log\Logger::registerErrorHandler($logger);

Then Stream your log files to Datadog

Configure the formatter in your Monolog configuration: declare the formatter field as follows:

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

It’s useful to add additional context data to your logs and events. Monolog makes this convenient by providing methods for setting thread-local context data that is then submitted automatically with all events. At any moment, log an event with contextual data:

<?php
  $logger->info('Adding a new user', array('username' => 'Seldaek'));

Monolog comes with a pre-processor feature. It’s a simple callback that enriches your events with metadata you can set (for example, the session ID, or the request id):

 <?php
  $log->pushProcessor(function ($record) {

      // record the current user
      $user = Acme::getCurrentUser();
      $record['context']['user'] = array(
          'name' => $user->getName(),
          'username' => $user->getUsername(),
          'email' => $user->getEmail(),
      );

      // Add various tags
      $record['ddtags'] = array('key' => 'value');

      // Add various generic context
      $record['extra']['key'] = 'value';

      return $record;
  });

Useful logging information comes from additional context data that you can add to your logs and events. Zend-Log makes this convenient by providing methods to set thread local context data that is then submitted automatically with all events. At any moment, log an event with contextual data:

<?php
  $logger->info('Adding a new user', array('username' => 'Seldaek'));

But, most importantly, the library comes with a Processor feature. Processors allow you to provide additional information to logs in an automated fashion. They are called from the logger before the event is passed to the writers; they receive the event array, and return an event array on completion.

Use cases include:

• Providing exception backtrace information.
• Injecting substitutions into the message.
• Injecting a request identifier (in order to later inspect logs for a specific identifier).

Take a peek to this code if you want to use it:

<?php
  $logger->addProcessor(new Zend\Log\Processor\Backtrace());
  $logger->addProcessor(new Zend\Log\Processor\PsrPlaceholder());
  $logger->addProcessor(new Zend\Log\Processor\ReferenceId());
  $logger->addProcessor(new Zend\Log\Processor\RequestId());

If you want to develop yours, refer the Zend documentation.

Add a session Processor to add variable context within your logs:

1. Implement your session Processor: This is an example of such a Processor. It knows the current session and it enriches the content of the log record with valuable information such as the requestId, sessionId, …

   <?php
     namespace Acme\Bundle\MonologBundle\Log;
   
     use Symfony\Component\HttpFoundation\Session\Session;
   
     class SessionRequestProcessor {
       private $session;
       private $sessionId;
       private $requestId;
       private $_server;
       private $_get;
       private $_post;
   
       public function __construct(Session $session) {
         $this->session = $session;
       }
   
       public function processRecord(array $record) {
         if (null === $this->requestId) {
           if ('cli' === php_sapi_name()) {
             $this->sessionId = getmypid();
           } else {
             try {
               $this->session->start();
               $this->sessionId = $this->session->getId();
             } catch (\RuntimeException $e) {
               $this->sessionId = '????????';
             }
           }
           $this->requestId = substr(uniqid(), -8);
           $this->_server = array(
             'http.url' => (@$_SERVER['HTTP_HOST']).'/'.(@$_SERVER['REQUEST_URI']),
             'http.method' => @$_SERVER['REQUEST_METHOD'],
             'http.useragent' => @$_SERVER['HTTP_USER_AGENT'],
             'http.referer' => @$_SERVER['HTTP_REFERER'],
             'http.x_forwarded_for' => @$_SERVER['HTTP_X_FORWARDED_FOR']
           );
           $this->_post = $this->clean($_POST);
           $this->_get = $this->clean($_GET);
         }
         $record['http.request_id'] = $this->requestId;
         $record['http.session_id'] = $this->sessionId;
         $record['http.url'] = $this->_server['http.url'];
         $record['http.method'] = $this->_server['http.method'];
         $record['http.useragent'] = $this->_server['http.useragent'];
         $record['http.referer'] = $this->_server['http.referer'];
         $record['http.x_forwarded_for'] = $this->_server['http.x_forwarded_for'];
   
         return $record;
       }
   
       protected function clean($array) {
         $toReturn = array();
         foreach(array_keys($array) as $key) {
           if (false !== strpos($key, 'password')) {
             // Do not add
           } else if (false !== strpos($key, 'csrf_token')) {
             // Do not add
           } else {
             $toReturn[$key] = $array[$key];
           }
         }
   
         return $toReturn;
       }
     }
   

2. Wire the Processor with Symfony:

 services:
    monolog.processor.session_request:
        class: Acme\Bundle\MonologBundle\Log\SessionRequestProcessor
        arguments:  [ @session ]
        tags:
            - { name: monolog.processor, method: processRecord }

3. Stream generated JSON file to Datadog.