How to Create Friendly Configuration for a Bundle
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Read the updated version of this page for Symfony 7.1 (the current stable version).
If you open your main application configuration directory (usually
config/packages/
), you'll see a number of different files, such as
framework.yaml
, twig.yaml
and doctrine.yaml
. Each of these
configures a specific bundle, allowing you to define options at a high level and
then let the bundle make all the low-level, complex changes based on your
settings.
For example, the following configuration tells the FrameworkBundle to enable the form integration, which involves the definition of quite a few services as well as integration of other related components:
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# config/packages/framework.yaml
framework:
form: 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:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:framework="http://symfony.com/schema/dic/symfony"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd
http://symfony.com/schema/dic/symfony
https://symfony.com/schema/dic/symfony/symfony-1.0.xsd"
>
<framework:config>
<framework:form/>
</framework:config>
</container>
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// config/packages/framework.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;
return static function (ContainerConfigurator $container) {
$container->extension('framework', [
'form' => true,
]);
};
Using the Bundle Extension
Imagine you are creating a new bundle - AcmeSocialBundle - which provides integration with Twitter. To make your bundle configurable to the user, you can add some configuration that looks like this:
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# config/packages/acme_social.yaml
acme_social:
twitter:
client_id: 123
client_secret: your_secret
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<!-- config/packages/acme_social.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:acme-social="http://example.org/schema/dic/acme_social"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd"
>
<acme-social:config>
<acme-social:twitter client-id="123"
client-secret="your_secret"
/>
</acme-social:config>
</container>
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// config/packages/acme_social.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;
return static function (ContainerConfigurator $container) {
$container->extension('acme_social', [
'twitter' => [
'client_id' => 123,
'client_secret' => 'your_secret',
],
]);
};
The basic idea is that instead of having the user override individual parameters, you let the user configure just a few, specifically created, options. As the bundle developer, you then parse through that configuration and load correct services and parameters inside an "Extension" class.
Note
The root key of your bundle configuration (acme_social
in the previous
example) is automatically determined from your bundle name (it's the
snake case of the bundle name without the Bundle
suffix ).
See also
Read more about the extension in How to Load Service Configuration inside a Bundle.
Tip
If a bundle provides an Extension class, then you should not generally override any service container parameters from that bundle. The idea is that if an Extension class is present, every setting that should be configurable should be present in the configuration made available by that class. In other words, the extension class defines all the public configuration settings for which backward compatibility will be maintained.
See also
For parameter handling within a dependency injection container see Using Parameters within a Dependency Injection Class.
Processing the $configs
Array
First things first, you have to create an extension class as explained in How to Load Service Configuration inside a Bundle.
Whenever a user includes the acme_social
key (which is the DI alias) in a
configuration file, the configuration under it is added to an array of
configurations and passed to the load()
method of your extension (Symfony
automatically converts XML and YAML to an array).
For the configuration example in the previous section, the array passed to your
load()
method will look like this:
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[
[
'twitter' => [
'client_id' => 123,
'client_secret' => 'your_secret',
],
],
]
Notice that this is an array of arrays, not just a single flat array of the
configuration values. This is intentional, as it allows Symfony to parse several
configuration resources. For example, if acme_social
appears in another
configuration file - say config/packages/dev/acme_social.yaml
- with
different values beneath it, the incoming array might look like this:
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[
// values from config/packages/acme_social.yaml
[
'twitter' => [
'client_id' => 123,
'client_secret' => 'your_secret',
],
],
// values from config/packages/dev/acme_social.yaml
[
'twitter' => [
'client_id' => 456,
],
],
]
The order of the two arrays depends on which one is set first.
But don't worry! Symfony's Config component will help you merge these values,
provide defaults and give the user validation errors on bad configuration.
Here's how it works. Create a Configuration
class in the
DependencyInjection
directory and build a tree that defines the structure
of your bundle's configuration.
The Configuration
class to handle the sample configuration looks like:
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// src/Acme/SocialBundle/DependencyInjection/Configuration.php
namespace Acme\SocialBundle\DependencyInjection;
use Symfony\Component\Config\Definition\Builder\TreeBuilder;
use Symfony\Component\Config\Definition\ConfigurationInterface;
class Configuration implements ConfigurationInterface
{
public function getConfigTreeBuilder()
{
$treeBuilder = new TreeBuilder('acme_social');
$treeBuilder->getRootNode()
->children()
->arrayNode('twitter')
->children()
->integerNode('client_id')->end()
->scalarNode('client_secret')->end()
->end()
->end() // twitter
->end()
;
return $treeBuilder;
}
}
4.2
Not passing the root node name to TreeBuilder
was deprecated in Symfony 4.2.
See also
The Configuration
class can be much more complicated than shown here,
supporting "prototype" nodes, advanced validation, XML-specific normalization
and advanced merging. You can read more about this in
the Config component documentation. You
can also see it in action by checking out some core Configuration
classes, such as the one from the FrameworkBundle Configuration or the
TwigBundle Configuration.
This class can now be used in your load()
method to merge configurations and
force validation (e.g. if an additional option was passed, an exception will be
thrown):
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// src/Acme/SocialBundle/DependencyInjection/AcmeSocialExtension.php
public function load(array $configs, ContainerBuilder $container)
{
$configuration = new Configuration();
$config = $this->processConfiguration($configuration, $configs);
// you now have these 2 config keys
// $config['twitter']['client_id'] and $config['twitter']['client_secret']
}
The processConfiguration()
method uses the configuration tree you've defined
in the Configuration
class to validate, normalize and merge all the
configuration arrays together.
Now, you can use the $config
variable to modify a service provided by your bundle.
For example, imagine your bundle has the following example config:
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<!-- src/Acme/SocialBundle/Resources/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"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd"
>
<services>
<service id="acme.social.twitter_client" class="Acme\SocialBundle\TwitterClient">
<argument></argument> <!-- will be filled in with client_id dynamically -->
<argument></argument> <!-- will be filled in with client_secret dynamically -->
</service>
</services>
</container>
In your extension, you can load this and dynamically set its arguments:
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// src/Acme/SocialBundle/DependencyInjection/AcmeSocialExtension.php
// ...
use Symfony\Component\Config\FileLocator;
use Symfony\Component\DependencyInjection\Loader\XmlFileLoader;
public function load(array $configs, ContainerBuilder $container)
{
$loader = new XmlFileLoader($container, new FileLocator(dirname(__DIR__).'/Resources/config'));
$loader->load('services.xml');
$configuration = new Configuration();
$config = $this->processConfiguration($configuration, $configs);
$definition = $container->getDefinition('acme.social.twitter_client');
$definition->replaceArgument(0, $config['twitter']['client_id']);
$definition->replaceArgument(1, $config['twitter']['client_secret']);
}
Tip
Instead of calling processConfiguration()
in your extension each time you
provide some configuration options, you might want to use the
ConfigurableExtension
to do this automatically for you:
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// src/Acme/HelloBundle/DependencyInjection/AcmeHelloExtension.php
namespace Acme\HelloBundle\DependencyInjection;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\HttpKernel\DependencyInjection\ConfigurableExtension;
class AcmeHelloExtension extends ConfigurableExtension
{
// note that this method is called loadInternal and not load
protected function loadInternal(array $mergedConfig, ContainerBuilder $container)
{
// ...
}
}
This class uses the getConfiguration()
method to get the Configuration
instance.
Processing the Configuration yourself
Using the Config component is fully optional. The load()
method gets an
array of configuration values. You can instead parse these arrays yourself
(e.g. by overriding configurations and using isset to check
for the existence of a value). Be aware that it'll be very hard to support XML:
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public function load(array $configs, ContainerBuilder $container)
{
$config = [];
// let resources override the previous set value
foreach ($configs as $subConfig) {
$config = array_merge($config, $subConfig);
}
// ... now use the flat $config array
}
Modifying the Configuration of Another Bundle
If you have multiple bundles that depend on each other, it may be useful to
allow one Extension
class to modify the configuration passed to another
bundle's Extension
class. This can be achieved using a prepend extension.
For more details, see How to Simplify Configuration of Multiple Bundles.
Dump the Configuration
The config:dump-reference
command dumps the default configuration of a
bundle in the console using the Yaml format.
As long as your bundle's configuration is located in the standard location
(YourBundle\DependencyInjection\Configuration
) and does not have
a constructor, it will work automatically. If you
have something different, your Extension
class must override the
Extension::getConfiguration()
method and return an instance of your Configuration
.
Supporting XML
Symfony allows people to provide the configuration in three different formats: Yaml, XML and PHP. Both Yaml and PHP use the same syntax and are supported by default when using the Config component. Supporting XML requires you to do some more things. But when sharing your bundle with others, it is recommended that you follow these steps.
Make your Config Tree ready for XML
The Config component provides some methods by default to allow it to correctly process XML configuration. See "Defining and Processing Configuration Values" of the component documentation. However, you can do some optional things as well, this will improve the experience of using XML configuration:
Choosing an XML Namespace
In XML, the XML namespace is used to determine which elements belong to the
configuration of a specific bundle. The namespace is returned from the
Extension::getNamespace()
method. By convention, the namespace is a URL (it doesn't have to be a valid
URL nor does it need to exist). By default, the namespace for a bundle is
http://example.org/schema/dic/DI_ALIAS
, where DI_ALIAS
is the DI alias of
the extension. You might want to change this to a more professional URL:
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// src/Acme/HelloBundle/DependencyInjection/AcmeHelloExtension.php
// ...
class AcmeHelloExtension extends Extension
{
// ...
public function getNamespace()
{
return 'http://acme_company.com/schema/dic/hello';
}
}
Providing an XML Schema
XML has a very useful feature called XML schema. This allows you to describe all possible elements and attributes and their values in an XML Schema Definition (an XSD file). This XSD file is used by IDEs for auto completion and it is used by the Config component to validate the elements.
In order to use the schema, the XML configuration file must provide an
xsi:schemaLocation
attribute pointing to the XSD file for a certain XML
namespace. This location always starts with the XML namespace. This XML
namespace is then replaced with the XSD validation base path returned from
Extension::getXsdValidationBasePath()
method. This namespace is then followed by the rest of the path from the base
path to the file itself.
By convention, the XSD file lives in the Resources/config/schema/
, but you
can place it anywhere you like. You should return this path as the base path:
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// src/Acme/HelloBundle/DependencyInjection/AcmeHelloExtension.php
// ...
class AcmeHelloExtension extends Extension
{
// ...
public function getXsdValidationBasePath()
{
return __DIR__.'/../Resources/config/schema';
}
}
Assuming the XSD file is called hello-1.0.xsd
, the schema location will be
https://acme_company.com/schema/dic/hello/hello-1.0.xsd
:
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<!-- config/packages/acme_hello.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:acme-hello="http://acme_company.com/schema/dic/hello"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd
http://acme_company.com/schema/dic/hello
https://acme_company.com/schema/dic/hello/hello-1.0.xsd"
>
<acme-hello:config>
<!-- ... -->
</acme-hello:config>
<!-- ... -->
</container>