module-logger

PSR-3 compliant PHP logging library with browser console and CLI output support. Designed for use in Magento 2 modules but has no Magento dependency.

Features

• BrowserConsoleLogger — outputs logs to browser DevTools console via injected <script> tags
  • Colored output by log level
  • Grouped logs with nesting
  • Global window.plog storage for in-browser debugging
  • Memory usage tracking per log entry
• CliLogger — outputs logs to terminal
  • ANSI colored output with auto-detection
  • Proper STDOUT/STDERR routing (errors → STDERR)
  • Grouped logs with indentation
  • Immediate or buffered output modes
• LoggerSingleton — keyed singleton, one logger instance per debug constant
  • Auto-selects CLI or Browser logger based on PHP_SAPI
  • Returns NullLogger when debug mode is off (zero overhead in production)

Installation

composer require swissup/module-logger

Usage

LoggerSingleton (recommended)

Enable debug mode by defining a constant before Magento bootstrap:

// in pub/index.php or app/etc/env.php
define('MY_MODULE_DEBUG', true);

Then use anywhere in your module:

use Swissup\Logger\Logger\LoggerSingleton;

$logger = LoggerSingleton::getInstance('MY_MODULE_DEBUG', '[MyModule]');

$logger->info('Processing started');
$logger->debug('Item loaded', ['id' => 42]);
$logger->warning('Cache miss', ['key' => 'product_1']);
$logger->error('Failed to connect', ['host' => 'localhost']);

When MY_MODULE_DEBUG is not defined or not true, getInstance() returns NullLogger — no overhead.

PSR-3 wrapper in your module

use Psr\Log\AbstractLogger;
use Swissup\Logger\Logger\LoggerSingleton;

class MyLogger extends AbstractLogger
{
    #[\ReturnTypeWillChange]
    public function log($level, $message, array $context = []): void
    {
        LoggerSingleton::getInstance('MY_MODULE_DEBUG', '[MyModule]')->log($level, $message, $context);
    }
}

Then bind it in di.xml:

<preference for="Psr\Log\LoggerInterface" type="MyVendor\MyModule\Logger\MyLogger"/>

BrowserConsoleLogger

Outputs logs as JavaScript to the browser console. Call flush() to get the <script> block and inject it into your HTML response.

use Swissup\Logger\Logger\BrowserConsoleLogger;

$logger = new BrowserConsoleLogger(enableGlobalStorage: true, prefix: '[MyModule]');

$logger->group('Processing request');
$logger->info('Step 1 complete');
$logger->debug('Data loaded', ['rows' => 150]);
$logger->warning('Slow query', ['ms' => 320]);
$logger->groupEnd();

// Inject into response HTML
echo $logger->flush();

Browser output example:

▼ [MyModule] Processing request
  14:05:59.123 INFO  Step 1 complete
  14:05:59.145 DEBUG Data loaded {rows: 150}
  14:05:59.201 WARN  Slow query {ms: 320}

Access all logs in DevTools console:

window.plog         // keyed by timestamp
window.plog._entries // ordered array

CliLogger

Outputs logs to terminal. Immediate output by default.

use Swissup\Logger\Logger\CliLogger;

$logger = new CliLogger(prefix: '[MyModule]');

$logger->group('Processing');
$logger->debug('Step 1', ['size' => 1024]);
$logger->warning('Patch failed', ['nodeId' => 123]);
$logger->groupEnd();

Terminal output:

┌─ [MyModule] Processing
│ 14:05:59.123 DEBUG   Step 1 {"size":1024}
│ 14:05:59.145 WARNING Patch failed {"nodeId":123}
└─

Buffered mode (accumulate then flush):

$logger = new CliLogger(prefix: '[MyModule]', immediateOutput: false);
$logger->info('Step 1');
$logger->info('Step 2');
$output = $logger->flush(); // write all at once

Log Levels

All PSR-3 log levels are supported:

Level	CLI color	Browser color	Console method
emergency	Red bg	#8B0000	console.error
alert	Magenta bold	#DC143C	console.error
critical	Red bold	#FF0000	console.error
error	Red	#FF4500	console.error
warning	Yellow	#FFA500	console.warn
notice	Cyan	#4169E1	console.info
info	Green	#008000	console.info
debug	Gray	#808080	console.debug

Message Interpolation

Context values are interpolated into {placeholder} patterns in messages:

$logger->info('User {id} logged in from {ip}', ['id' => 42, 'ip' => '127.0.0.1']);
// → "User 42 logged in from 127.0.0.1"

Context Sanitization

Context arrays are automatically sanitized before JSON encoding:

• Resources → "resource(stream)"
• Exceptions/Throwable → {_type, class, message, code, file, line}
• Objects with __toString → string value
• JsonSerializable objects → JSON serialized
• Other objects → "object(ClassName)"
• Nested arrays → recursively sanitized