Composer plugin and a library for config assembling

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dev-master / 1.0.x-dev 2021-09-07 20:54 UTC

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Last update: 2021-09-16 15:48:20 UTC


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Yii Config

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This Composer plugin provides assembling of configurations distributed with composer packages. It allows putting configuration needed to use a package right inside thus implementing a plugin system. The package becomes a plugin holding both the code and its configuration.


  • PHP 7.4 or higher.
  • JSON PHP extension.
  • Composer 2.0 or higher.


composer require yiisoft/config --prefer-dist

How it works?

The package consist of two parts: Composer plugin and config loader.

After composer updates its autoload file, and that happens after dump-autoload, require, update or remove, Composer plugin:

  • Scans installed packages for config-plugin extra option in their composer.json.
  • Copies missing config files into the project configs.
  • Writes a merge plan into config/packages/merge_plan.php. It includes configuration from each package composer.json.
  • Tracks change to configuration files from the vendor by storing metadata in the config/packages/dist.lock file.
  • In the interactive console mode it asks what to do with modified configs after updating packages in the vendor.

In the application entry point, usually index.php, we create an instance of config loader and require a configuration we need:

$config = new \Yiisoft\Config\Config(dirname(__DIR__));
$webConfig = $config->get('web');

The web in the above is a config group. The config loader obtains it runtime according to the merge plan.

Config groups

Each config group represents a set of configs that is merged into a single array. It is defined per package in each package composer.json:

"extra": {
    "config-plugin": {
        "params": [
        "common": "config/common.php",
        "web": [
        "other": "config/other.php"


  • ? - marks optional files. Absence of files not marked with it will cause exception.

    "params": [

    It's okay if params-local.php will not found, but it's not okay if params.php will be absent.

  • * - marks wildcard path. It means zero or more matches by wildcard mask.

    "web": [

    It will collect all web.php in any sub-folders of src/Modules/ in config folder.

  • $ - reference to another config.

    "params": [
    "params-console": [
    "params-web": [

    Output files params-console.php and params-web.php will contain params.php and params-local.php.

Define your configs like the following:


return [
    'components' => [
        'db' => [
            'class' => \my\Db::class,
            'name' => $params['db.name'],
            'password' => $params['db.password'],

A special variable $params is read from params config.

Using sub-configs

In order to access a sub-config, use the following in your config:

'routes' => $config->get('routes');


A number of options is available both for Composer plugin and a config loader. Composer options are specified in composer.json:

"extra": {
    "config-plugin-options": {
      "output-directory": "/config/packages",
      "source-directory": "/config",
    "config-plugin": {
        // ...


In the above output-directory points to where configs will be copied to. The path is relative to where composer.json is. The option is read for the root package, which is typically an application. Default is "/config/packages".

If you change output directory, don't forget to adjust configs path when creating an instance of Config. Usually that is index.php:

$config = new \Yiisoft\Config\Config(
    'config/packages', // Configs path.

$webConfig = $config->get('web');

source-directory points to where to read configs from for the package the option is specified for. The option is read for all packages. The value is a path relative to where package composer.json is. Default value is empty string.

Recursive merge of arrays

By default, recursive merging of arrays in configuration files is not performed. If you want to recursively merge arrays in a certain group of configs, such as params, you must pass group names to the Config constructor:

use \Yiisoft\Config\Config;

$config = new Config(

$appConfig = $config->get('events-web'); // merged recursively


The plugin supports creating additional environments added to the base configuration. This allows you to create multiple configurations for the application such as production and development.

The environment configuration options are added to the main configuration options, but do not replace them.

The environments are specified in the composer.json file of your application:

"extra": {
    "config-plugin": {
        "params": "config/params.php",
        "web": "config/web.php",
    "config-plugin-environments": {
        "dev": {
            "params": "config/dev/params.php",
            "app": [
        "prod": {
            "app": "config/prod/app.php"

Configuration defines the merge process. One of the environments from config-plugin-environments is merged with the main configuration defined by config-plugin. In given example, in the dev environment we use $web configuration from the main environment.

This configuration has the following structure:

config/             Configuration root directory.
    dev/            Development environment files.
        app.php     Development environment app group configuration.
        params.php  Development environment parameters.
    prod/           Production environment files.
        app.php     Production environment app group configuration.
    params.php      Main configuration parameters.
    web.php         Мain configuration web group configuration.

To choose an environment to be used you must specify its name when creating an instance of Config:

$config = new \Yiisoft\Config\Config(

$appConfig = $config->get('app');

If defined in an environment, params will be merged with params from the main configuration, and could be used as $params in all configurations.


The plugin adds extra config-diff command to composer. It displays the difference between the vendor and application configuration files in the console.

# For all config files
composer config-diff

# For the config files of the specified packages
composer config-diff yiisoft/aliases yiisoft/view


Unit testing

The package is tested with PHPUnit. To run tests:

./vendor/bin/phpunit --testdox --no-interaction

Mutation testing

The package tests are checked with Infection mutation framework with Infection Static Analysis Plugin. To run it:


Static analysis

The code is statically analyzed with Psalm. To run static analysis:



The config package is free software. It is released under the terms of the BSD License. Please see LICENSE for more information.

Maintained by Yii Software.


The plugin is heavily inspired by Composer config plugin originally created by HiQDev (http://hiqdev.com/) in 2016 and then adopted by Yii.

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