Contributed by
Christophe Coevoet
in #522.

One of the best practice when developing a Symfony application is to make it configurable via a parameters.yml file. It contains information such as the database name, the mailer hostname, and custom configuration parameters.

As those parameters can be different on your local machine, your testing environment, your production servers, and even between developers working on the same project, it is not recommended to store it in the project repository. Instead, the repository should contain a paramaters.yml.dist file with sensible defaults that can be used as a good starting point for everyone.

Then, whenever a developer starts working on the project, the parameters`.yml file must be created by using the parameters.yml.dist as a template. That works quite well, but whenever a new value is added to the template, you must remember to update the main parameter file accordingly.

As of Symfony 2.3, the Standard Edition comes with a new bundle that automates the tedious work. Whenever you run composer install, a script creates the parameters.yml file if it does not exist and allows you to customize all the values interactively. Moreover, if you use the --no-interaction flag, it will silently fallback to the default values.

Please remember that storing password or any other sensitive information in the parameters.yml file is not a good idea, and Symfony provides other ways to do the same in a more secure way.