How to group log files by date using dot-log

TL;DR

dot-log is a powerful, easily customizable logging tool. Version 3.1.1 adds the ability to use datetime formatter strings right in the stream option of a log writer, and fixes an issue where caching dot-log configs caused logs to be written to a single file instead of being grouped by date.

Prerequisites

• dot-log installed and configured inside your application. If it's not installed, follow the steps in Logging with dot-log in Zend Expressive and Dotkernel.
• Otherwise, make sure you're using the latest version by running:

composer update dotkernel/dot-log

If your application logs messages to a single file with a static name (e.g. log/dk.log), you can skip the rest of this guide - logging will work as before.

Configuring the logger with Dotkernel

Your application should already have a config/autoload/error-handling.global.php file similar to:

<?php

return [
    'dot-errorhandler' => [
        'loggerEnabled' => true,
        'logger' => 'dot-log.default_logger'
    ],
    'dot_log' => [
        'loggers' => [
            'default_logger' => [
                'writers' => [
                    'FileWriter' => [
                        'name' => 'stream',
                        'priority' => \Laminas\Log\Logger::ALERT,
                        'options' => [
                            'stream' => sprintf('%s/../../log/error-log-%s.log', __DIR__, date('Y-m-d')),
                            // explicitly log all messages
                            'filters' => [
                                'allMessages' => [
                                    'name' => 'priority',
                                    'options' => [
                                        'operator' => '>=',
                                        'priority' => \Laminas\Log\Logger::EMERG,
                                    ],
                                ],
                            ],
                            'formatter' => [
                                'name' => \Laminas\Log\Formatter\Json::class,
                            ],
                        ],
                    ],
                ],
            ],
        ],
    ],
];

1. Locate every log writer by navigating to dot_log -> loggers -> default_logger -> writers.

2. For each writer, find the stream option containing the path to the log file. If it looks like:

   'stream' => sprintf('%s/../../log/error-log-%s.log', __DIR__, date('Y-m-d'))
   

3. Replace it with:

   'stream' => __DIR__ . '/../../log/error-log-{Y}-{m}-{d}.log'
   

4. Clear the config cache:

   php bin/clear-config-cache.php
   

If the log path uses other date format specifiers, adapt them accordingly - the full list is in the PHP date() manual.

Configuring the logger without Dotkernel

Locate the dot-log config (probably /config/autoload/log.global.php), which should look similar to the Dotkernel example but keyed under a custom logger name (e.g. my_logger) and may define multiple writers (e.g. a general file writer, a warnings-only writer, and a warnings-or-higher writer).

1. Locate every writer by navigating to dot_log -> loggers -> my_logger -> writers.

2. For each writer, find the stream option. If it looks like:

   'stream' => sprintf('%s/../../log/dk-%s.log', __DIR__, date('Y-m-d'))
   

3. Replace it with:

   'stream' => __DIR__ . '/../../log/error-log-{Y}-{m}-{d}.log',
   

4. Make sure you clear your application's config before usage.

As before, adapt any other date format specifiers as needed - see the PHP date() manual.

Frequently Asked Questions