Flex recipes

Your new Symfony project is tiny on purpose: no mailer, no ORM, no templates until you decide you need them. When you do, install the feature with Composer.

Here is the magic: Symfony Flex, a Composer plugin, applies the package's recipe automatically. It creates the configuration files, registers the bundle and adds the environment variables the package needs. Zero manual setup.

Secrets and machine-specific values live in environment variables, following the twelve-factor app philosophy. The recipe already added a sensible default to your .env file. And don't worry: this file only stores harmless development defaults. In production, you define real environment variables or use Symfony's encrypted secrets vault.

This works for hundreds of packages: try composer require orm, composer require security or composer require debug. Un-installing is just as clean: composer remove mailer reverts all the changes made by the recipe.