How to Import Configuration Files/Resources
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Read the updated version of this page for Symfony 7.2 (the current stable version).
Tip
In this section, service configuration files are referred to as resources. This is to highlight the fact that, while most configuration resources will be files (e.g. YAML, XML, PHP), Symfony is so flexible that configuration could be loaded from anywhere (e.g. a database or even via an external web service).
The service container is built using a single configuration resource
(app/config/config.yml
by default). All other service configuration
(including the core Symfony and third-party bundle configuration) must
be imported from inside this file in one way or another. This gives you absolute
flexibility over the services in your application.
External service configuration can be imported in two different ways. The first
method, commonly used to import other resources, is via the imports
directive. The second method, using dependency injection extensions, is used by
third-party bundles to load the configuration. Read on to learn more about both
methods.
Importing Configuration with imports
So far, you've placed your app.mailer
service container definition directly
in the services configuration file (e.g. app/config/services.yml
). If your
application ends up having many services, this file becomes huge and hard to
maintain. To avoid this, you can split your service configuration into multiple
service files:
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# app/config/services/mailer.yml
parameters:
app.mailer.transport: sendmail
services:
app.mailer:
class: AppBundle\Mailer
arguments: ['%app.mailer.transport%']
The definition itself hasn't changed, only its location. To make the service
container load the definitions in this resource file, use the imports
key
in any already loaded resource (e.g. app/config/services.yml
or
app/config/config.yml
):
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# app/config/services.yml
imports:
- { resource: services/mailer.yml }
The resource
location, for files, is either a relative path from the
current file or an absolute path.
Note
Due to the way in which parameters are resolved, you cannot use them to build paths in imports dynamically. This means that something like the following doesn't work:
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# app/config/config.yml
imports:
- { resource: '%kernel.root_dir%/parameters.yml' }
Importing Configuration via Container Extensions
Third-party bundle container configuration, including Symfony core services, are usually loaded using another method that's more flexible and easy to configure in your application.
Internally, each bundle defines its services like you've seen so far. However,
these files aren't imported using the import
directive. These bundles use a
dependency injection extension to load the files. The extension also allows
bundles to provide configuration to dynamically load some services.
Take the FrameworkBundle - the core Symfony Framework bundle - as an example. The presence of the following code in your application configuration invokes the service container extension inside the FrameworkBundle:
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# app/config/config.yml
framework:
secret: xxxxxxxxxx
form: true
# ...
When the resources are parsed, the container looks for an extension that
can handle the framework
directive. The extension in question, which lives
in the FrameworkBundle, is invoked and the service configuration for the
FrameworkBundle is loaded.
The settings under the framework
directive (e.g. form: true
) indicate
that the extension should load all services related to the Form component. If
form was disabled, these services wouldn't be loaded and Form integration would
not be available.
When installing or configuring a bundle, see the bundle's documentation for how the services for the bundle should be installed and configured. The options available for the core bundles can be found inside the Reference Guide.
See also
If you want to use dependency injection extensions in your own shared bundles and provide user friendly configuration, take a look at the How to Load Service Configuration inside a Bundle article.