(PSR-3) Loggers and Logging Utilities

Utilities for and Loggers for PSR-3: Logger Interface.

• LogLevelFilter - LogLevelFilter is a PSR Logger that filters logs based on the log level. It can be used to filter out log messages that are not needed for a specific use case.
• LogLevelLoggerMux - LogLevelLoggerMux is a PSR Logger that multiplexes logs to different loggers based on the log level.
• LoggerVerbosityFilter - LoggerVerbosityFilter mutes log messages based on a given integer verbosity level.
• LoggerWithContext - LoggerWithContext is a logger that adds a given context to all log messages before delegating to another logger.
• MemoryLogger - MemoryLogger is a PSR Logger that stores all logs in local memory.
• MultiLogger - MultiLogger is a PSR Logger that delegates logs to multiple other loggers.
• StreamResourceLogger - StreamResourceLogger is a PSR Logger that writes to a stream resource.

Requirements

• psr/log: ^1 || ^2 || ^3
• php: ^7.4 || ^8.0

Installing

Install the latest version with:

composer require 'corpus/loggers'

Example

This example demonstrates how the loggers may be chained together to create complex interactions

<?php

use Corpus\Loggers\LoggerWithContext;
use Corpus\Loggers\LogLevelFilter;
use Corpus\Loggers\MemoryLogger;
use Corpus\Loggers\MultiLogger;
use Corpus\Loggers\StreamResourceLogger;
use Psr\Log\LogLevel;

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

$memoryLogger = new MemoryLogger;
$cliLogger    = new StreamResourceLogger(
	fopen('php://output', 'w')
);

$logger = new MultiLogger(
	new LogLevelFilter(
		(new LoggerWithContext($memoryLogger))->withContext([ 'Logger' => 'Number 1' ]),
		[ Psr\Log\LogLevel::INFO ]
	),
	new LogLevelFilter(
		(new LoggerWithContext($cliLogger))->withContext([ 'Logger' => 'Number 2' ]),
		[ Psr\Log\LogLevel::INFO, LogLevel::DEBUG ]
	),
	new LogLevelFilter(
		(new LoggerWithContext($cliLogger))->withContext([ 'Logger' => 'Number 3' ]),
		[ Psr\Log\LogLevel::INFO, LogLevel::DEBUG ],
		true // reverse filter - only log levels NOT in the array
	)
);

$logger->info('Hello World', [ 'hello' => 'world' ]);
$logger->debug('How are you?', [ 'foo' => 'bar' ]);
$logger->error('I am fine', [ 'bar' => 'baz', 'baz' => 'qux' ]);

echo "\n--- dumping memory logger ---\n\n";

var_export($memoryLogger->getLogs());

2023-11-30T05:34:35+00:00      info: Hello World
    Logger: 'Number 2'
     hello: 'world'
2023-11-30T05:34:35+00:00     debug: How are you?
    Logger: 'Number 2'
       foo: 'bar'
2023-11-30T05:34:35+00:00     error: I am fine
    Logger: 'Number 3'
       bar: 'baz'
       baz: 'qux'

--- dumping memory logger ---

array (
  0 =>
  array (
    'level' => 'info',
    'message' => 'Hello World',
    'context' =>
    array (
      'Logger' => 'Number 1',
      'hello' => 'world',
    ),
  ),
)

Documentation

Class: \Corpus\Loggers\Interfaces\LoggerWithContextInterface

Method: LoggerWithContextInterface->withContext

function withContext(array $context) : self

Returns a new instance with the given context
replacing the existing context.

---

Method: LoggerWithContextInterface->withAddedContext

function withAddedContext(array $context) : self

Returns a new instance with the given context
added to the existing context.

Class: \Corpus\Loggers\Interfaces\MultiLoggerInterface

Method: MultiLoggerInterface->withAdditionalLoggers

function withAdditionalLoggers(\Psr\Log\LoggerInterface ...$loggers) : self

withAdditionalLoggers returns a new instance with the given loggers
added to the list of loggers to delegate to.

Class: \Corpus\Loggers\Interfaces\WithAdditionalLoggersInterface

Method: WithAdditionalLoggersInterface->withAdditionalLoggers

function withAdditionalLoggers(\Psr\Log\LoggerInterface ...$loggers) : self

withAdditionalLoggers returns a new instance with the given loggers
added to the list of loggers to delegate to.

Class: \Corpus\Loggers\Interfaces\WithContextInterface

Method: WithContextInterface->withContext

function withContext(array $context) : self

Returns a new instance with the given context
replacing the existing context.

---

Method: WithContextInterface->withAddedContext

function withAddedContext(array $context) : self

Returns a new instance with the given context
added to the existing context.

Class: \Corpus\Loggers\LoggerVerbosityFilter

LoggerVerbosityFilter mutes log messages based on a given integer verbosity level.

By default,

• level 0 logs no messages.
• level 1 logs emergency, alert, critical, and error messages.
• level 2 logs emergency, alert, critical, error, warning, and notice messages.
• level 3 logs emergency, alert, critical, error, warning, notice, and info messages.
• level 4 or greater logs emergency, alert, critical, error, warning, notice, info, and debug messages.

The levels can be changed by passing a callback redefine the verbosity level for each log level.

The verbosity level can be changed by calling withVerbosity()

Method: LoggerVerbosityFilter->__construct

function __construct(\Psr\Log\LoggerInterface $logger [, int $verbosity = 0 [, ?callable $verbosityFromLevelCallback = null]])

Parameters:

• callable | null $verbosityFromLevelCallback - A callback that takes a Psr\Log\LogLevel log level string and returns an integer verbosity level. If null, the default callback will be used.

---

Method: LoggerVerbosityFilter->withVerbosity

function withVerbosity(int $verbosity) : self

Returns a new instance with the specified verbosity level.

---

Method: LoggerVerbosityFilter->withVerbosityFromLevelCallback

function withVerbosityFromLevelCallback(callable $verbosityFromLevelCallback) : self

Returns a new instance with the specified verbosity level callback.

Class: \Corpus\Loggers\LoggerWithContext

LoggerWithContext is a logger that adds a given context to all log messages before delegating to another logger.

This is useful for adding context to all log messages, such as the current request ID, IP address or the current user ID.

Method: LoggerWithContext->__construct

function __construct(\Psr\Log\LoggerInterface $logger [, array $context = []])

Create a new LoggerWithContext instance with the given logger and context.

The given context will be added to all log messages.

Parameters:

• \Psr\Log\LoggerInterface $logger - The logger to delegate to.
• array $context - The context to add to all log messages.

---

Method: LoggerWithContext->withContext

function withContext(array $context) : self

Returns a new instance with the given context
replacing the existing context.

---

Method: LoggerWithContext->withAddedContext

function withAddedContext(array $context) : self

Returns a new instance with the given context
added to the existing context.

Class: \Corpus\Loggers\LogLevelFilter

LogLevelFilter is a PSR Logger that filters logs based on the log level.

It can be used to filter out log messages that are not needed for a specific use case.

For example, you may want to log all messages at the DEBUG level to a file, but only log messages at the ERROR level or higher to the console.

This logger can be used to filter out the DEBUG messages from the console logger.

This logger accepts a list of log levels to filter, and a boolean indicating whether to exclude or include the given log levels.

Method: LogLevelFilter->__construct

function __construct(\Psr\Log\LoggerInterface $logger, array $levels [, bool $exclude = false])

Parameters:

• string[] $levels - The log levels to filter.
• bool $exclude - Whether to exclude the given levels, or include them.

Class: \Corpus\Loggers\LogLevelLoggerMux

LogLevelLoggerMux is a PSR Logger that multiplexes logs to different loggers based on the log level.

Method: LogLevelLoggerMux->__construct

function __construct([ ?\Psr\Log\LoggerInterface $defaultLogger = null [, ?\Psr\Log\LoggerInterface $emergencyLogger = null [, ?\Psr\Log\LoggerInterface $alertLogger = null [, ?\Psr\Log\LoggerInterface $criticalLogger = null [, ?\Psr\Log\LoggerInterface $errorLogger = null [, ?\Psr\Log\LoggerInterface $warningLogger = null [, ?\Psr\Log\LoggerInterface $noticeLogger = null [, ?\Psr\Log\LoggerInterface $infoLogger = null [, ?\Psr\Log\LoggerInterface $debugLogger = null]]]]]]]]])

Parameters:

• \Psr\Log\LoggerInterface | null $defaultLogger - The default logger to use for levels where no other logger is specified. If null, a Psr\Log\NullLogger will be used.

---

Method: LogLevelLoggerMux->withEmergencyLogger

function withEmergencyLogger(\Psr\Log\LoggerInterface $logger) : self

Returns a new instance with the specified logger handling the Emergency log level.

---

Method: LogLevelLoggerMux->withAlertLogger

function withAlertLogger(\Psr\Log\LoggerInterface $logger) : self

Returns a new instance with the specified logger handling the Alert log level.

---

Method: LogLevelLoggerMux->withCriticalLogger

function withCriticalLogger(\Psr\Log\LoggerInterface $logger) : self

Returns a new instance with the specified logger handling the Critical log level.

---

Method: LogLevelLoggerMux->withErrorLogger

function withErrorLogger(\Psr\Log\LoggerInterface $logger) : self

Returns a new instance with the specified logger handling the Error log level.

---

Method: LogLevelLoggerMux->withWarningLogger

function withWarningLogger(\Psr\Log\LoggerInterface $logger) : self

Returns a new instance with the specified logger handling the Warning log level.

---

Method: LogLevelLoggerMux->withNoticeLogger

function withNoticeLogger(\Psr\Log\LoggerInterface $logger) : self

Returns a new instance with the specified logger handling the Notice log level.

---

Method: LogLevelLoggerMux->withInfoLogger

function withInfoLogger(\Psr\Log\LoggerInterface $logger) : self

Returns a new instance with the specified logger handling the Info log level.

---

Method: LogLevelLoggerMux->withDebugLogger

function withDebugLogger(\Psr\Log\LoggerInterface $logger) : self

Returns a new instance with the specified logger handling the Debug log level.

Class: \Corpus\Loggers\MemoryLogger

MemoryLogger is a PSR Logger that stores all logs in local memory.

This is primarily useful for testing purposes.

<?php
namespace Corpus\Loggers;

class MemoryLogger {
	public const KEY_LEVEL = 'level';
	public const KEY_MESSAGE = 'message';
	public const KEY_CONTEXT = 'context';
}

---

Method: MemoryLogger->getLogs

function getLogs() : array

getLogs returns all logs that have been logged to this logger.

The returned array is a list of log records, each of which is an array keyed by

• MemoryLogger::KEY_LEVEL : The log level
• MemoryLogger::KEY_MESSAGE : The log message
• MemoryLogger::KEY_CONTEXT : The log context

Returns:

• array[]

---

Method: MemoryLogger->clearLogs

function clearLogs() : void

clearLogs clears all logs that have been logged to this logger.

Class: \Corpus\Loggers\MultiLogger

MultiLogger is a PSR Logger that delegates logs to multiple other loggers.

Method: MultiLogger->__construct

function __construct(\Psr\Log\LoggerInterface ...$loggers)

Create a new MultiLogger instance with the given loggers to delegate to.

---

Method: MultiLogger->withAdditionalLoggers

function withAdditionalLoggers(\Psr\Log\LoggerInterface ...$loggers) : self

withAdditionalLoggers returns a new instance with the given loggers
added to the list of loggers to delegate to.

Class: \Corpus\Loggers\StreamResourceLogger

StreamResourceLogger is a PSR Logger that writes to a stream resource.

This is particularly useful for writing to STDERR or STDOUT, or to a file.

Method: StreamResourceLogger->__construct

function __construct($resource)

Parameters:

• resource $resource - Writable stream resource

Throws: \Corpus\Loggers\Exceptions\LoggerArgumentException - If the given resource is not a stream

Throws: \Corpus\Loggers\Exceptions\LoggerInitException - If the given resource is not writable