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Configuring Symfony (and Environments)

Configuring Symfony (and Environments)

Symfony applications can install third-party packages (bundles, libraries, etc.) to bring in new features (services) to your project. Each package can be customized via configuration files that live - by default - in the config/ directory.

Configuration: config/packages/

The configuration for each package can be found in config/packages/. For instance, the framework bundle is configured in config/packages/framework.yaml:

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    # config/packages/framework.yaml
    framework:
        secret: '%env(APP_SECRET)%'
        #default_locale: en
        #csrf_protection: ~
        #http_method_override: true
        #trusted_hosts: ~
        # https://symfony.com/doc/current/reference/configuration/framework.html#handler-id
        #session:
        #    # The native PHP session handler will be used
        #    handler_id: ~
        #esi: ~
        #fragments: ~
        php_errors:
            log: true
    
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    <!-- config/packages/framework.xml -->
    <?xml version="1.0" encoding="UTF-8" ?>
    <container xmlns="http://symfony.com/schema/dic/services"
        xmlns:framework="http://symfony.com/schema/dic/framework"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd
            http://symfony.com/schema/dic/framework http://symfony.com/schema/dic/framework/framework-1.0.xsd"
    >
        <framework:config secret="%env(APP_SECRET)%">
            <framework:php-errors log="true" />
        </framework:config>
    </container>
    
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    # config/packages/framework.php
    $container->loadFromExtension('framework', [
        'secret' => '%env(APP_SECRET)%',
        //'default_locale' => 'en',
        //'csrf_protection' => null,
        //'http_method_override' => true,
        //'trusted_hosts' => null,
        // https://symfony.com/doc/current/reference/configuration/framework.html#handler-id
        //'session' => [
        //    // The native PHP session handler will be used
        //    'handler_id' => null,
        //],
        //'esi' => null,
        //'fragments' => null,
        'php_errors' => [
            'log' => true,
        ],
    ]);
    

The top-level key (here framework) references configuration for a specific bundle (FrameworkBundle in this case).

Throughout the documentation, all configuration examples will be shown in three formats (YAML, XML and PHP). YAML is used by default, but you can choose whatever you like best. There is no performance difference:

  • The YAML Format: Simple, clean and readable;
  • XML: More powerful than YAML at times & supports IDE autocompletion;
  • PHP: Very powerful but less readable than standard configuration formats.

Configuration Reference & Dumping

There are two ways to know what keys you can configure:

  1. Use the Reference Section;
  2. Use the config:dump-reference command.

For example, if you want to configure something related to the framework bundle, you can see an example dump of all available configuration options by running:

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$ php bin/console config:dump-reference framework

The parameters Key: Parameters (Variables)

The configuration has some special top-level keys. One of them is called parameters: it's used to define variables that can be referenced in any other configuration file. For example, when you install the translation package, a locale parameter is added to config/services.yaml:

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    # config/services.yaml
    parameters:
        locale: en
    
    # ...
    
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    <!-- config/services.xml -->
    <?xml version="1.0" encoding="UTF-8" ?>
    <container xmlns="http://symfony.com/schema/dic/services"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:framework="http://symfony.com/schema/dic/symfony"
        xsi:schemaLocation="http://symfony.com/schema/dic/services
            http://symfony.com/schema/dic/services/services-1.0.xsd
            http://symfony.com/schema/dic/symfony
            http://symfony.com/schema/dic/symfony/symfony-1.0.xsd">
    
        <parameters>
            <parameter key="locale">en</parameter>
        </parameters>
    
        <!-- ... -->
    </container>
    
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    // config/services.php
    $container->setParameter('locale', 'en');
    // ...
    

This parameter is then referenced in the framework config in config/packages/translation.yaml:

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    # config/packages/translation.yaml
    framework:
        # any string surrounded by two % is replaced by that parameter value
        default_locale: '%locale%'
    
        # ...
    
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    <!-- config/packages/translation.xml -->
    <?xml version="1.0" encoding="UTF-8" ?>
    <container xmlns="http://symfony.com/schema/dic/services"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:framework="http://symfony.com/schema/dic/symfony"
        xsi:schemaLocation="http://symfony.com/schema/dic/services
            http://symfony.com/schema/dic/services/services-1.0.xsd
            http://symfony.com/schema/dic/symfony
            http://symfony.com/schema/dic/symfony/symfony-1.0.xsd">
    
        <!-- any string surrounded by two % is replaced by that parameter value -->
        <framework:config default-locale="%locale%">
            <!-- ... -->
        </framework:config>
    </container>
    
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    // config/packages/translation.php
    $container->loadFromExtension('framework', array(
        // any string surrounded by two % is replaced by that parameter value
        'default_locale' => '%locale%',
    
        // ...
    ));
    

You can define whatever parameter names you want under the parameters key of any configuration file. To reference a parameter, surround its name with two percent signs - e.g. %locale%.

You can also set parameters dynamically, like from environment variables. See How to Set external Parameters in the Service Container.

For more information about parameters - including how to reference them from inside a controller - see Service Parameters.

The .env File & Environment Variables

There is also a .env file which is loaded. Its contents become environment variables in the dev environment, making it easier to reference environment variables in your code. When you install packages, more environment variables are added to this file. But you can also add your own variables.

Environment variables can be referenced in any other configuration files by using a special syntax. For example, if you install the doctrine package, then you will have an environment variable called DATABASE_URL in your .env file. This is referenced inside config/packages/doctrine.yaml:

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# config/packages/doctrine.yaml
doctrine:
    dbal:
        url: '%env(DATABASE_URL)%'

        # the resolve: prefix will resolve parameters *inside* the env variable
        # url: '%env(resolve:DATABASE_URL)%'

For more details about environment variables, see Environment Variables.

The .env file is special, because it defines the values that usually change on each server. For example, the database credentials on your local development machine might be different from your workmates. That's why this file is not committed to the shared repository and is only stored on your machine. In fact, the .gitignore file that comes with Symfony prevents it from being committed.

However, a .env.dist file is committed (with dummy values). This file isn't read by Symfony: it's just a reference so that Symfony knows which variables need to be defined in the .env file. If you add or remove keys to .env, add or remove them from .env.dist too, so both files are always in sync.

Environments & the Other Config Files

You have just one app, but whether you realize it or not, you need it to behave differently at different times:

  • While developing, you want your app to log everything and expose nice debugging tools;
  • After deploying to production, you want that same app to be optimized for speed and only log errors.

How can you make one application behave in two different ways? With environments.

You've probably already been using the dev environment without even knowing it. After you deploy, you'll use the prod environment.

To learn more about how to execute and control each environment, see How to Master and Create new Environments.

Keep Going!

Congratulations! You've tackled the basics in Symfony. Next, learn about each part of Symfony individually by following the guides. Check out:

And the many other topics.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.