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Symfony2 – Franz Jordán 2011
Configuration Formats
Throughout the chapters, all configuration examples will be shown in all three formats (YAML,
XML and PHP). Each has its own advantages and disadvantages. The choice of which to use is up
to you:
YAML: Simple, clean and readable;
XML: More powerful than YAML at times and supports IDE autocompletion;
PHP: Very powerful but less readable than standard configuration formats.
Environments
An application can run in various environments. The different environments share the same PHP
code (apart from the front controller), but use different configuration. For instance,
a devenvironment will log warnings and errors, while a prod environment will only log errors.
Some files are rebuilt on each request in the dev environment (for the developer's convenience),
but cached in the prod environment. All environments live together on the same machine and
execute the same application.
A Symfony2 project generally begins with three environments (dev, test and prod), though
creating new environments is easy. You can view your application in different environments
simply by changing the front controller in your browser. To see the application in
the dev environment, access the application via the development front controller:
http://localhost/app_dev.php/hello/Ryan
If you'd like to see how your application will behave in the production environment, call
the prodfront controller instead:
http://localhost/app.php/hello/Ryan
If you open the web/app.php file, you'll find that it's configured explicitly to use
theprod environment:
$kernel = new AppKernel('prod', false);
You can create a new front controller for a new environment by copying this file and
changing prod to some other value.
Since the prod environment is optimized for speed; the configuration, routing and Twig
templates are compiled into flat PHP classes and cached. When viewing changes in
the prod environment, you'll need to clear these cached files and allow them to rebuild:
php app/console cache:clear --env=prod
The test environment is used when running automated tests and cannot be accessed directly
through the browser. See the testing chapter for more details.
Environment Configuration
The AppKernel class is responsible for actually loading the configuration file of your choice:
// app/AppKernel.php
public function registerContainerConfiguration(LoaderInterface $loader)
{
$loader->load(__DIR__.'/config/config_'.$this->getEnvironment().'.yml');
}
You already know that the .yml extension can be changed to .xml or .php if you prefer to use
either XML or PHP to write your configuration. Notice also that each environment loads its own
configuration file. Consider the configuration file for the dev environment.
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