Installation

Requirements

• PHP 8.3 or higher
• Composer
• For file output: a local filesystem that supports flock() and renaming a file within its directory

Composer

Install the package via Composer:

composer require solophp/logger

Dependencies

{
    "require": {
        "php": "^8.3",
        "psr/log": "^3.0",
        "psr/clock": "^1.0"
    }
}

• psr/log — the LoggerInterface the logger implements; the package provides psr/log-implementation 3.0
• psr/clock — the PSR-20 ClockInterface the logger and the file writer read the time from

No PHP extension beyond the default build is needed.

Basic Setup

use Psr\Log\LogLevel;
use Solo\Logger\Logger;
use Solo\Logger\Rotation\RotationOptions;

$logger = Logger::file(
    path: '/var/log/app/app.log',
    minLevel: LogLevel::INFO,
    rotation: new RotationOptions(maxBytes: 10 * 1024 * 1024, maxFiles: 14),
);

$logger->info('Application started');

Logger::file() builds the common setup: a FileWriter for the path, the formatter you pass — LineFormatter by default — and a clock in the given timezone, UTC by default. The directory is created on the first write, not before.

In a container, or for a worker whose standard error is collected, write there instead:

use Solo\Logger\Formatter\JsonFormatter;

$logger = Logger::stream(minLevel: LogLevel::INFO, formatter: new JsonFormatter());

See Streams.

As a PSR-3 Service

The logger implements Psr\Log\LoggerInterface, so any library that accepts a PSR-3 logger takes it as is. Build it once — in a factory or your container — and share it:

use Psr\Log\LoggerInterface;
use Psr\Log\LogLevel;
use Solo\Logger\Formatter\JsonFormatter;
use Solo\Logger\Logger;
use Solo\Logger\Rotation\RotationOptions;
use Solo\Logger\Rotation\Schedule;

final class LoggerFactory
{
    public static function create(string $logDirectory, bool $debug): LoggerInterface
    {
        return Logger::file(
            path: $logDirectory . '/app.log',
            minLevel: $debug ? LogLevel::DEBUG : LogLevel::INFO,
            formatter: new JsonFormatter(),
            rotation: new RotationOptions(schedule: Schedule::Daily, maxFiles: 30),
            filePermissions: 0640,
        );
    }
}

A logger keeps no state between records, and every FileWriter coordinates with the other processes that write the same file, so one instance per application is enough — also under PHP-FPM, queue workers and cron jobs running at the same time.

Disabling Logging

A Logger always has a destination. Where no output is wanted, inject PSR-3's Psr\Log\NullLogger instead.

Next Steps

• Quick Start — Levels, placeholders, exceptions, channels and formats
• Log Rotation — Size and time limits, retention, many processes
• Decorators — Several destinations, fail-safe logging, shared context