.. index::
    single: Environments; External parameters

How to Set external Parameters in the Service Container
=======================================================

In the article :doc:`/configuration`, 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
---------------------

Symfony will grab any environment variable prefixed with ``SYMFONY__`` and
set it as a parameter in the service container. Some transformations are
applied to the resulting parameter name:

* ``SYMFONY__`` prefix is removed;
* Parameter name is lowercased;
* Double underscores are replaced with a period, as a period is not
  a valid character in an environment variable name.

For example, if you're using Apache, environment variables can be set using the
`SetEnv`_ directive with the following ``VirtualHost`` configuration:

.. code-block:: apache

    <VirtualHost *:80>
        ServerName      Symfony
        DocumentRoot    "/path/to/symfony_2_app/web"
        DirectoryIndex  index.php index.html
        SetEnv          SYMFONY__DATABASE__USER user
        SetEnv          SYMFONY__DATABASE__PASSWORD secret

        <Directory "/path/to/symfony_2_app/web">
            AllowOverride All
            Allow from All
        </Directory>
    </VirtualHost>

For Nginx web servers, the environment variables can be set with the `fastcgi_param`_
directive. For example, in the configuration file where the ``fastcgi_params``
file is included:

.. code-block:: nginx

    server {
        server_name domain.tld www.domain.tld;
        root /var/www/project/web;

        location / {
            try_files $uri /app.php$is_args$args;
        }

        location ~ ^/app\.php(/|$) {
            fastcgi_pass unix:/var/run/php5-fpm.sock;
            fastcgi_split_path_info ^(.+\.php)(/.*)$;
            include fastcgi_params;
            fastcgi_param SCRIPT_FILENAME $realpath_root$fastcgi_script_name;
            fastcgi_param DOCUMENT_ROOT $realpath_root;
            fastcgi_param SYMFONY__DATABASE__USER user;
            fastcgi_param SYMFONY__DATABASE__PASSWORD secret;
            internal;
        }

        # ...
    }

.. note::

    The examples above are for an Apache and Nginx configuration. However, this
    will work for any web server which supports the setting of environment
    variables.

    Also, in order for your console to work (which does not use a web server),
    you must export these as shell variables. On a Unix system, you can run
    the following:

    .. code-block:: terminal

        $ export SYMFONY__DATABASE__USER=user
        $ export SYMFONY__DATABASE__PASSWORD=secret

Now that you have declared an environment variable, it will be present
in the PHP ``$_SERVER`` global variable. Symfony then automatically sets all
``$_SERVER`` variables prefixed with ``SYMFONY__`` as parameters in the service
container.

You can now reference these parameters wherever you need them.

.. configuration-block::

    .. code-block:: yaml

        doctrine:
            dbal:
                driver:   pdo_mysql
                dbname:   symfony_project
                user:     '%database.user%'
                password: '%database.password%'

    .. code-block:: xml

        <!-- app/config/config.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
                    driver="pdo_mysql"
                    dbname="symfony_project"
                    user="%database.user%"
                    password="%database.password%"
                />
            </doctrine:config>

        </container>

    .. code-block:: php

        $container->loadFromExtension('doctrine', array(
            'dbal' => array(
                'driver'   => 'pdo_mysql',
                'dbname'   => 'symfony_project',
                'user'     => '%database.user%',
                'password' => '%database.password%',
            )
        ));

Constants
---------

The container also has support for setting PHP constants as parameters.
See :ref:`component-di-parameters-constants` for more details.

Miscellaneous Configuration
---------------------------

The ``imports`` directive can be used to pull in parameters stored elsewhere.
Importing a PHP file gives you the flexibility to add whatever is needed
in the container. The following imports a file named ``parameters.php``.

.. configuration-block::

    .. code-block:: yaml

        # app/config/config.yml
        imports:
            - { resource: parameters.php }

    .. code-block:: xml

        <!-- app/config/config.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">

            <imports>
                <import resource="parameters.php" />
            </imports>

        </container>

    .. code-block:: php

        // app/config/config.php
        $loader->import('parameters.php');

.. note::

    A resource file can be one of many types. PHP, XML, YAML, INI, and
    closure resources are all supported by the ``imports`` directive.

In ``parameters.php``, tell the service container the parameters that you wish
to set. This is useful when important configuration is in a non-standard
format. The example below includes a Drupal database configuration in
the Symfony service container::

    // app/config/parameters.php
    include_once('/path/to/drupal/sites/default/settings.php');
    $container->setParameter('drupal.database.url', $db_url);

.. _`SetEnv`: http://httpd.apache.org/docs/current/env.html
.. _`fastcgi_param`: http://nginx.org/en/docs/http/ngx_http_fastcgi_module.html#fastcgi_param