You are browsing the documentation for Symfony 3.4 which is not maintained anymore.
Consider upgrading your projects to Symfony 5.3.
The Config Component
The Config Component¶
The Config component provides several classes to help you find, load, combine, fill and validate configuration values of any kind, whatever their source may be (YAML, XML, INI files, or for instance a database).
$ composer require symfony/config:^3.4
If you install this component outside of a Symfony application, you must
vendor/autoload.php file in your code to enable the class
autoloading mechanism provided by Composer. Read
this article for more details.
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