Configuration and Dependency Injection

Configuration and dependency injection in one PSR-11 container, with environments that inherit from each other and autowiring only where you choose it.

Why

Every application has a dev, a test, a staging and a production configuration that are mostly the same. Copying the files means a change has to be made in four places, and the container that builds your services usually decides for you how much is wired by magic.

Config builds the environments as a hierarchy:

$dev     = new Environment('dev');
$test    = new Environment('test', [$dev]);                  // dev, plus what test changes
$base    = new Environment('base', [$dev], abstract: true);  // shared, never loaded directly
$prod    = new Environment('prod', [$base], final: true);    // nothing may inherit from prod

• Write a value once. An environment inherits everything from its parents and only states what is different. abstract and final keep the hierarchy honest.
• Explicit bindings, autowiring when you want it. DI::bind() declares a service and its decisions (implementation, singleton, constructor arguments); an Autowire::rule() resolves a whole namespace by type hints. You choose per namespace, trading convenience for a plain lookup.

Features

• PSR-11 Compatible: Implements PSR-11 Container Interface for standardized dependency injection
• Auto-Initialization: Automatically loads configuration from a bootstrap file with zero setup
• Static Facade: Clean, Laravel-style static API for accessing configuration anywhere
• Environment-Based Configuration: Easily switch between development, production, and custom environments
• Multiple Configuration Formats: Support for both PHP arrays and .env files
• Dependency Injection: Simple API for defining and resolving dependencies
• Type Conversion: Built-in parsers for converting configuration values to specific types
• Caching Support: Optional caching of configuration values for improved performance
• Environment Inheritance: Environments can inherit from one another to reduce configuration duplication
• Abstract & Final Environments: Design flexible environment hierarchies with constraints
• Performance Optimizations: Configure caching modes for different use cases

Quick Start with Auto-Initialization

The fastest way to get started is using the auto-initialization feature:

<?php
// 1. Create config/ConfigBootstrap.php
use ByJG\Config\ConfigInitializeInterface;
use ByJG\Config\Definition;
use ByJG\Config\Environment;

return new class implements ConfigInitializeInterface {
    public function loadDefinition(?string $env = null): Definition {
        $dev = new Environment('dev');
        $prod = new Environment('prod', [$dev]);

        return (new Definition())
            ->addEnvironment($dev)
            ->addEnvironment($prod);
    }
};

<?php
// 2. Create your config file (config/config-dev.php)
return [
    'database' => [
        'host' => 'localhost',
        'port' => 3306
    ],
    'app_name' => 'My Application',
    'debug' => true
];

<?php
// 3. Use Config anywhere in your app - no initialization needed!
use ByJG\Config\Config;

$appName = Config::get('app_name'); // "My Application"
$dbHost = Config::get('database')['host']; // "localhost"

Traditional Example

You can also use the traditional approach without auto-initialization:

<?php
// 1. Create a config file (config/config-dev.php)
return [
    'database' => [
        'host' => 'localhost',
        'port' => 3306
    ],
    'app_name' => 'My Application',
    'debug' => true
];

// 2. Set up and load the configuration
use ByJG\Config\Definition;
use ByJG\Config\Environment;

// Define the environments
$dev = new Environment('dev');
$prod = new Environment('prod', [$dev]); // prod inherits from dev

// Create and build the definition
$definition = (new Definition())
    ->addEnvironment($dev)
    ->addEnvironment($prod);

// Build with the current environment (using APP_ENV environment variable)
$container = $definition->build();

// 3. Use the configuration values
$appName = $container->get('app_name'); // "My Application"
$dbHost = $container->get('database')['host']; // "localhost"

Dependency Injection Example

<?php
// 1. Define your classes
namespace MyApp;

class DatabaseService 
{
    private $host;
    private $port;
    
    public function __construct(array $database) 
    {
        $this->host = $database['host'];
        $this->port = $database['port'];
    }
}

class UserRepository 
{
    private $db;
    
    public function __construct(DatabaseService $db) 
    {
        $this->db = $db;
    }
}

// 2. Register them in your config file
use ByJG\Config\DependencyInjection as DI;
use ByJG\Config\Param;

return [
    'database' => [
        'host' => 'localhost',
        'port' => 3306
    ],
    
    // Register the database service. A Param refers to the whole entry, so it receives the array
    \MyApp\DatabaseService::class => DI::bind(\MyApp\DatabaseService::class)
        ->withConstructorArgs([Param::get('database')])
        ->toSingleton(),
    
    // Register the repository with auto-injection
    \MyApp\UserRepository::class => DI::bind(\MyApp\UserRepository::class)
        ->withInjectedConstructor()
        ->toInstance(),

    // For mixed injection (auto-inject classes, manually provide scalars)
    \MyApp\UserService::class => DI::bind(\MyApp\UserService::class)
        ->withInjectedConstructorOverrides([
            'apiKey' => 'my-secret-key'  // Manually provide scalar values
        ])
        ->toInstance()
];

// 3. Use the services from the container
$userRepo = $container->get(\MyApp\UserRepository::class);

Documentation

Start with the fundamentals and move toward the advanced features following this order:

• Set up the configuration files – Define environments, file naming, and directory structure;
• Load the configuration – Build Definition instances and work with the PSR-11 container;
• Using the Config Facade – Access container values through the static API;
• Auto-Initialization – Let Config bootstrap itself from config/ConfigBootstrap.php;
• Define dependency injection – Bind services, constructor parameters, and factories;
• Work with special types – Parse .env values through built-in or custom parsers;
• Configure your webserver – Expose environment variables in different runtimes;
• Follow good practices – Apply conventions that keep configuration manageable;
• Explore advanced features – Use caching, inheritance constraints, and container helpers;

Installation

composer require "byjg/config"

Running Tests

./vendor/bin/phpunit

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Open source ByJG