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How to Set external Parameters in the Service Container
How to Set external Parameters in the Service Container¶
In Configuring Symfony (and Environments), you learned how to manage your application configuration. At times, it may benefit your application to store certain credentials outside of your project code. Database configuration is one such example. The flexibility of the Symfony service container allows you to easily do this.
Environment Variables¶
You can reference environment variables by using special parameters named after
the variables you want to use enclosed between env()
. Their actual values
will be resolved at runtime (once per request), so that dumped containers can be
reconfigured dynamically even after being compiled.
For example, when installing the doctrine
recipe, database configuration is
put in a DATABASE_URL
environment variable:
1 2 | # .env
DATABASE_URL="mysql://db_user:db_password@127.0.0.1:3306/db_name"
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This variable is referenced in the service container configuration using
%env(DATABASE_URL)%
:
- YAML
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# config/packages/doctrine.yaml doctrine: dbal: url: '%env(DATABASE_URL)%' # ...
- XML
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<!-- config/packages/doctrine.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:doctrine="http://symfony.com/schema/dic/doctrine" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd http://symfony.com/schema/dic/doctrine http://symfony.com/schema/dic/doctrine/doctrine-1.0.xsd"> <doctrine:config> <doctrine:dbal url="%env(DATABASE_URL)%" /> </doctrine:config> </container>
- PHP
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// config/packages/doctrine.php $container->loadFromExtension('doctrine', array( 'dbal' => array( 'url' => '%env(DATABASE_URL)%', ) ));
You can also give the env()
parameters a default value: the default value
will be used whenever the corresponding environment variable is not found:
- YAML
1 2 3
# config/services.yaml parameters: env(DATABASE_HOST): localhost
- XML
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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" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"> <parameters> <parameter key="env(DATABASE_HOST)">localhost</parameter> </parameters> </container>
- PHP
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// config/services.php $container->setParameter('env(DATABASE_HOST)', 'localhost');
Configuring Environment Variables in Production¶
During development, you'll use the .env
file to configure your environment
variables. On your production server, it is recommended to configure these at
the web server level. If you're using Apache or Nginx, you can use e.g. one of
the following:
- Apache
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<VirtualHost *:80> # ... SetEnv DATABASE_URL "mysql://db_user:db_password@127.0.0.1:3306/db_name" </VirtualHost>
- Nginx
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fastcgi_param DATABASE_URL "mysql://db_user:db_password@127.0.0.1:3306/db_name";
Caution
Beware that dumping the contents of the $_SERVER
and $_ENV
variables
or outputting the phpinfo()
contents will display the values of the
environment variables, exposing sensitive information such as the database
credentials.
Constants¶
The container also has support for setting PHP constants as parameters. See Constants as Parameters for more details.
Miscellaneous Configuration¶
You can mix whatever configuration format you like (YAML, XML and PHP) in
config/packages/
. Importing a PHP file gives you the flexibility to add
whatever is needed in the container. For instance, you can create a
drupal.php
file in which you set a database URL based on Drupal's database
configuration:
1 2 3 4 5 6 7 | // config/packages/drupal.php
// import Drupal's configuration
include_once('/path/to/drupal/sites/default/settings.php');
// set a app.database_url parameter
$container->setParameter('app.database_url', $db_url);
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This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.