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Configuring Symfony

Configuration Files

Symfony applications are configured with the files stored in the config/ directory, which has this default structure:

your-project/
├─ config/
│  ├─ packages/
│  ├─ bundles.php
│  ├─ routes.yaml
│  └─ services.yaml
  • The routes.yaml file defines the routing configuration </routing>;
  • The services.yaml file configures the services of the service container </service_container>;
  • The bundles.php file enables/disables packages in your application;
  • The config/packages/ directory stores the configuration of every package installed in your application.

Packages (also called "bundles" in Symfony and "plugins/modules" in other projects) add ready-to-use features to your projects.

When using Symfony Flex <symfony-flex>, which is enabled by default in Symfony applications, packages update the bundles.php file and create new files in config/packages/ automatically during their installation. For example, this is the default file created by the "API Platform" bundle:

# config/packages/api_platform.yaml
api_platform:
    mapping:
        paths: ['%kernel.project_dir%/src/Entity']

Splitting the configuration into lots of small files might appear intimidating for some Symfony newcomers. However, you'll get used to them quickly and you rarely need to change these files after package installation.

Tip

To learn about all the available configuration options, check out the Symfony Configuration Reference </reference/index> or run the config:dump-reference command.

Configuration Formats

Unlike other frameworks, Symfony doesn't impose a specific format on you to configure your applications, but lets you choose between YAML, XML and PHP. Throughout the Symfony documentation, all configuration examples will be shown in these three formats.

There isn't any practical difference between formats. In fact, Symfony transforms all of them into PHP and caches them before running the application, so there's not even any performance difference.

YAML is used by default when installing packages because it's concise and very readable. These are the main advantages and disadvantages of each format:

  • YAML: simple, clean and readable, but not all IDEs support autocompletion and validation for it. Learn the YAML syntax </reference/formats/yaml>;
  • XML: autocompleted/validated by most IDEs and is parsed natively by PHP, but sometimes it generates configuration considered too verbose. Learn the XML syntax;
  • PHP: very powerful and it allows you to create dynamic configuration with arrays or a ConfigBuilder <config-config-builder>.

Note

By default Symfony loads the configuration files defined in YAML and PHP formats. If you define configuration in XML format, update the Symfony\\Bundle\\FrameworkBundle\\Kernel\\MicroKernelTrait::configureContainer and/or Symfony\\Bundle\\FrameworkBundle\\Kernel\\MicroKernelTrait::configureRoutes methods in the src/Kernel.php file to add support for the .xml file extension.

Importing Configuration Files

Symfony loads configuration files using the Config component </components/config>, which provides advanced features such as importing other configuration files, even if they use a different format:

# config/services.yaml
imports:
    - { resource: 'legacy_config.php' }

    # glob expressions are also supported to load multiple files
    - { resource: '/etc/myapp/*.yaml' }

    # ignore_errors: not_found silently discards errors if the loaded file doesn't exist
    - { resource: 'my_config_file.xml', ignore_errors: not_found }
    # ignore_errors: true silently discards all errors (including invalid code and not found)
    - { resource: 'my_other_config_file.xml', ignore_errors: true }

# ...
<!-- 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
        http://symfony.com/schema/dic/symfony
        https://symfony.com/schema/dic/symfony/symfony-1.0.xsd">

    <imports>
        <import resource="legacy_config.php"/>
        <!-- glob expressions are also supported to load multiple files -->
        <import resource="/etc/myapp/*.yaml"/>

        <!-- ignore-errors="not_found" silently discards errors if the loaded file doesn't exist -->
        <import resource="my_config_file.yaml" ignore-errors="not_found"/>
        <!-- ignore-errors="true" silently discards all errors (including invalid code and not found) -->
        <import resource="my_other_config_file.yaml" ignore-errors="true"/>
    </imports>

    <!-- ... -->
</container>
// config/services.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;

return static function (ContainerConfigurator $container): void {
    $container->import('legacy_config.php');

    // glob expressions are also supported to load multiple files
    $container->import('/etc/myapp/*.yaml');

    // the third optional argument of import() is 'ignore_errors'
    // 'ignore_errors' set to 'not_found' silently discards errors if the loaded file doesn't exist
    $container->import('my_config_file.yaml', null, 'not_found');
    // 'ignore_errors' set to true silently discards all errors (including invalid code and not found)
    $container->import('my_config_file.yaml', null, true);
};

// ...

Configuration Parameters

Sometimes the same configuration value is used in several configuration files. Instead of repeating it, you can define it as a "parameter", which is like a reusable configuration value. By convention, parameters are defined under the parameters key in the config/services.yaml file:

# config/services.yaml
parameters:
    # the parameter name is an arbitrary string (the 'app.' prefix is recommended
    # to better differentiate your parameters from Symfony parameters).
    app.admin_email: 'something@example.com'

    # boolean parameters
    app.enable_v2_protocol: true

    # array/collection parameters
    app.supported_locales: ['en', 'es', 'fr']

    # binary content parameters (encode the contents with base64_encode())
    app.some_parameter: !!binary VGhpcyBpcyBhIEJlbGwgY2hhciAH

    # PHP constants as parameter values
    app.some_constant: !php/const GLOBAL_CONSTANT
    app.another_constant: !php/const App\Entity\BlogPost::MAX_ITEMS

    # Enum case as parameter values
    app.some_enum: !php/enum App\Enum\PostState::Published

# ...
<!-- 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
        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">

    <parameters>
        <!-- the parameter name is an arbitrary string (the 'app.' prefix is recommended
             to better differentiate your parameters from Symfony parameters). -->
        <parameter key="app.admin_email">something@example.com</parameter>

        <!-- boolean parameters -->
        <parameter key="app.enable_v2_protocol">true</parameter>
        <!-- if you prefer to store the boolean value as a string in the parameter -->
        <parameter key="app.enable_v2_protocol" type="string">true</parameter>

        <!-- array/collection parameters -->
        <parameter key="app.supported_locales" type="collection">
            <parameter>en</parameter>
            <parameter>es</parameter>
            <parameter>fr</parameter>
        </parameter>

        <!-- binary content parameters (encode the contents with base64_encode()) -->
        <parameter key="app.some_parameter" type="binary">VGhpcyBpcyBhIEJlbGwgY2hhciAH</parameter>

        <!-- PHP constants as parameter values -->
        <parameter key="app.some_constant" type="constant">GLOBAL_CONSTANT</parameter>
        <parameter key="app.another_constant" type="constant">App\Entity\BlogPost::MAX_ITEMS</parameter>

        <!-- Enum case as parameter values -->
        <parameter key="app.some_enum" type="enum">App\Enum\PostState::Published</parameter>
    </parameters>

    <!-- ... -->
</container>
// config/services.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;

use App\Entity\BlogPost;
use App\Enum\PostState;

return static function (ContainerConfigurator $container): void {
    $container->parameters()
        // the parameter name is an arbitrary string (the 'app.' prefix is recommended
        // to better differentiate your parameters from Symfony parameters).
        ->set('app.admin_email', 'something@example.com')

        // boolean parameters
        ->set('app.enable_v2_protocol', true)

        // array/collection parameters
        ->set('app.supported_locales', ['en', 'es', 'fr'])

        // binary content parameters (use the PHP escape sequences)
        ->set('app.some_parameter', 'This is a Bell char: \x07')

        // PHP constants as parameter values
        ->set('app.some_constant', GLOBAL_CONSTANT)
        ->set('app.another_constant', BlogPost::MAX_ITEMS)

        // Enum case as parameter values
        ->set('app.some_enum', PostState::Published);
};

// ...

Caution

By default and when using XML configuration, the values between <parameter> tags are not trimmed. This means that the value of the following parameter will be '\n something@example.com\n':

<parameter key="app.admin_email">
    something@example.com
</parameter>

If you want to trim the value of your parameter, use the trim attribute. When using it, the value of the following parameter will be something@example.com:

<parameter key="app.admin_email" trim="true">
    something@example.com
</parameter>

Once defined, you can reference this parameter value from any other configuration file using a special syntax: wrap the parameter name in two % (e.g. %app.admin_email%):

# config/packages/some_package.yaml
some_package:
    # any string surrounded by two % is replaced by that parameter value
    email_address: '%app.admin_email%'
<!-- config/packages/some_package.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">

    <!-- any string surrounded by two % is replaced by that parameter value -->
    <some-package:config email-address="%app.admin_email%">
        <!-- ... -->
    </some-package:config>
</container>
// config/packages/some_package.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;
use function Symfony\Component\DependencyInjection\Loader\Configurator\param;

return static function (ContainerConfigurator $container): void {
    $container->extension('some_package', [
        // when using the param() function, you only have to pass the parameter name...
        'email_address' => param('app.admin_email'),

        // ... but if you prefer it, you can also pass the name as a string
        // surrounded by two % (same as in YAML and XML formats) and Symfony will
        // replace it by that parameter value
        'email_address' => '%app.admin_email%',
    ]);
};

Note

If some parameter value includes the % character, you need to escape it by adding another %, so Symfony doesn't consider it a reference to a parameter name:

# config/services.yaml
parameters:
    # Parsed as 'https://symfony.com/?foo=%s&amp;bar=%d'
    url_pattern: 'https://symfony.com/?foo=%%s&amp;bar=%%d'
<!-- config/services.xml -->
<parameters>
    <parameter key="url_pattern">http://symfony.com/?foo=%%s&amp;bar=%%d</parameter>
</parameters>
// config/services.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;

return static function (ContainerConfigurator $container): void {
    $container->parameters()
        ->set('url_pattern', 'http://symfony.com/?foo=%%s&amp;bar=%%d');
};

Configuration parameters are very common in Symfony applications. Some packages even define their own parameters (e.g. when installing the translation package, a new locale parameter is added to the config/services.yaml file).

Tip

By convention, parameters whose names start with a dot . (for example, .mailer.transport), are available only during the container compilation. They are useful when working with Compiler Passes </service_container/compiler_passes> to declare some temporary parameters that won't be available later in the application.

Later in this article you can read how to get configuration parameters in controllers and services <configuration-accessing-parameters>.

Configuration Environments

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

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

The files stored in config/packages/ are used by Symfony to configure the application services </service_container>. In other words, you can change the application behavior by changing which configuration files are loaded. That's the idea of Symfony's configuration environments.

A typical Symfony application begins with three environments:

  • dev for local development,
  • prod for production servers,
  • test for automated tests </testing>.

When running the application, Symfony loads the configuration files in this order (the last files can override the values set in the previous ones):

  1. The files in config/packages/*.<extension>;
  2. the files in config/packages/<environment-name>/*.<extension>;
  3. config/services.<extension>;
  4. config/services_<environment-name>.<extension>.

Take the framework package, installed by default, as an example:

  • First, config/packages/framework.yaml is loaded in all environments and it configures the framework with some options;
  • In the prod environment, nothing extra will be set as there is no config/packages/prod/framework.yaml file;
  • In the dev environment, there is no file either ( config/packages/dev/framework.yaml does not exist).
  • In the test environment, the config/packages/test/framework.yaml file is loaded to override some of the settings previously configured in config/packages/framework.yaml.

In reality, each environment differs only somewhat from others. This means that all environments share a large base of common configuration, which is put in files directly in the config/packages/ directory.

Tip

You can also define options for different environments in a single configuration file using the special when keyword:

# config/packages/webpack_encore.yaml
webpack_encore:
    # ...
    output_path: '%kernel.project_dir%/public/build'
    strict_mode: true
    cache: false

# cache is enabled only in the "prod" environment
when@prod:
    webpack_encore:
        cache: true

# disable strict mode only in the "test" environment
when@test:
    webpack_encore:
        strict_mode: false

# YAML syntax allows to reuse contents using "anchors" (&some_name) and "aliases" (*some_name).
# In this example, 'test' configuration uses the exact same configuration as in 'prod'
when@prod: &webpack_prod
    webpack_encore:
        # ...
when@test: *webpack_prod
<!-- config/packages/webpack_encore.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
        http://symfony.com/schema/dic/symfony
        https://symfony.com/schema/dic/symfony/symfony-1.0.xsd">
    <webpack-encore:config
        output-path="%kernel.project_dir%/public/build"
        strict-mode="true"
        cache="false"
    />

    <!-- cache is enabled only in the "test" environment -->
    <when env="prod">
        <webpack-encore:config cache="true"/>
    </when>

    <!-- disable strict mode only in the "test" environment -->
    <when env="test">
        <webpack-encore:config strict-mode="false"/>
    </when>
</container>
// config/packages/framework.php
use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;
use Symfony\Config\WebpackEncoreConfig;

return static function (WebpackEncoreConfig $webpackEncore, ContainerConfigurator $container): void {
    $webpackEncore
        ->outputPath('%kernel.project_dir%/public/build')
        ->strictMode(true)
        ->cache(false)
    ;

    // cache is enabled only in the "prod" environment
    if ('prod' === $container->env()) {
        $webpackEncore->cache(true);
    }

    // disable strict mode only in the "test" environment
    if ('test' === $container->env()) {
        $webpackEncore->strictMode(false);
    }
};

See the configureContainer() method of the Kernel class </configuration/front_controllers_and_kernel> to learn everything about the loading order of configuration files.

Selecting the Active Environment

Symfony applications come with a file called .env located at the project root directory. This file is used to define the value of environment variables and it's explained in detail later in this article <config-dot-env>.

Open the .env file (or better, the .env.local file if you created one) and edit the value of the APP_ENV variable to change the environment in which the application runs. For example, to run the application in production:

# .env (or .env.local)
APP_ENV=prod

This value is used both for the web and for the console commands. However, you can override it for commands by setting the APP_ENV value before running them:

# Use the environment defined in the .env file
$ php bin/console command_name

# Ignore the .env file and run this command in production
$ APP_ENV=prod php bin/console command_name

Creating a New Environment

The default three environments provided by Symfony are enough for most projects, but you can define your own environments too. For example, this is how you can define a staging environment where the client can test the project before going to production:

  1. Create a configuration directory with the same name as the environment (in this case, config/packages/staging/);
  2. Add the needed configuration files in config/packages/staging/ to define the behavior of the new environment. Symfony loads the config/packages/*.yaml files first, so you only need to configure the differences to those files;
  3. Select the staging environment using the APP_ENV env var as explained in the previous section.

Tip

It's common for environments to be similar to each other, so you can use symbolic links between config/packages/<environment-name>/ directories to reuse the same configuration.

Instead of creating new environments, you can use environment variables as explained in the following section. This way you can use the same application and environment (e.g. prod) but change its behavior thanks to the configuration based on environment variables (e.g. to run the application in different scenarios: staging, quality assurance, client review, etc.)

Configuration Based on Environment Variables

Using environment variables (or "env vars" for short) is a common practice to:

  • Configure options that depend on where the application is run (e.g. the database credentials are usually different in production versus your local machine);
  • Configure options that can change dynamically in a production environment (e.g. to update the value of an expired API key without having to redeploy the entire application).

In other cases, it's recommended to keep using configuration parameters <configuration-parameters>.

Use the special syntax %env(ENV_VAR_NAME)% to reference environment variables. The values of these options are resolved at runtime (only once per request, to not impact performance) so you can change the application behavior without having to clear the cache.

This example shows how you could configure the application secret using an env var:

# config/packages/framework.yaml
framework:
    # by convention the env var names are always uppercase
    secret: '%env(APP_SECRET)%'
    # ...
<!-- 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/framework"
    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">

    <!-- by convention the env var names are always uppercase -->
    <framework:config secret="%env(APP_SECRET)%"/>

</container>
// config/packages/framework.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;

return static function (ContainerConfigurator $container): void {
    $container->extension('framework', [
        // by convention the env var names are always uppercase
        'secret' => '%env(APP_SECRET)%',
    ]);
};

Note

Your env vars can also be accessed via the PHP super globals $_ENV and $_SERVER (both are equivalent):

$databaseUrl = $_ENV['DATABASE_URL']; // mysql://db_user:db_password@127.0.0.1:3306/db_name
$env = $_SERVER['APP_ENV']; // prod

However, in Symfony applications there's no need to use this, because the configuration system provides a better way of working with env vars.

The values of env vars can only be strings, but Symfony includes some env var processors </configuration/env_var_processors> to transform their contents (e.g. to turn a string value into an integer).

To define the value of an env var, you have several options:

  • Add the value to a .env file <config-dot-env>;
  • Encrypt the value as a secret <configuration-secrets>;
  • Set the value as a real environment variable in your shell or your web server.

If your application tries to use an env var that hasn't been defined, you'll see an exception. You can prevent that by defining a default value for the env var. To do so, define a parameter with the same name as the env var using this syntax:

# config/packages/framework.yaml
parameters:
    # if the SECRET env var value is not defined anywhere, Symfony uses this value
    env(SECRET): 'some_secret'

# ...
<!-- 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">

    <parameters>
        <!-- if the SECRET env var value is not defined anywhere, Symfony uses this value -->
        <parameter key="env(SECRET)">some_secret</parameter>
    </parameters>

    <!-- ... -->
</container>
// config/packages/framework.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;

use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Config\FrameworkConfig;

return static function (ContainerBuilder $container, FrameworkConfig $framework) {
    // if the SECRET env var value is not defined anywhere, Symfony uses this value
    $container->setParameter('env(SECRET)', 'some_secret');

    // ...
};

Tip

Some hosts - like Platform.sh - offer easy utilities to manage env vars in production.

Note

Some configuration features are not compatible with env vars. For example, defining some container parameters conditionally based on the existence of another configuration option. When using an env var, the configuration option always exists, because its value will be null when the related env var is not defined.

Danger

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.

The values of the env vars are also exposed in the web interface of the Symfony profiler </profiler>. In practice this shouldn't be a problem because the web profiler must never be enabled in production.

Configuring Environment Variables in .env Files

Instead of defining env vars in your shell or your web server, Symfony provides a convenient way to define them inside a .env (with a leading dot) file located at the root of your project.

The .env file is read and parsed on every request and its env vars are added to the $_ENV & $_SERVER PHP variables. Any existing env vars are never overwritten by the values defined in .env, so you can combine both.

For example, to define the DATABASE_URL env var shown earlier in this article, you can add:

# .env
DATABASE_URL="mysql://db_user:db_password@127.0.0.1:3306/db_name"

This file should be committed to your repository and (due to that fact) should only contain "default" values that are good for local development. This file should not contain production values.

In addition to your own env vars, this .env file also contains the env vars defined by the third-party packages installed in your application (they are added automatically by Symfony Flex <symfony-flex> when installing packages).

Tip

Since the .env file is read and parsed on every request, you don't need to clear the Symfony cache or restart the PHP container if you're using Docker.

.env File Syntax

Add comments by prefixing them with #:

# database credentials
DB_USER=root
DB_PASS=pass # this is the secret password

Use environment variables in values by prefixing variables with $:

DB_USER=root
DB_PASS=${DB_USER}pass # include the user as a password prefix

Caution

The order is important when some env var depends on the value of other env vars. In the above example, DB_PASS must be defined after DB_USER. Moreover, if you define multiple .env files and put DB_PASS first, its value will depend on the DB_USER value defined in other files instead of the value defined in this file.

Define a default value in case the environment variable is not set:

DB_USER=
DB_PASS=${DB_USER:-root}pass # results in DB_PASS=rootpass

Embed commands via $() (not supported on Windows):

START_TIME=$(date)

Caution

Using $() might not work depending on your shell.

Tip

As a .env file is a regular shell script, you can source it in your own shell scripts:

$ source .env

Overriding Environment Values via .env.local

If you need to override an environment value (e.g. to a different value on your local machine), you can do that in a .env.local file:

# .env.local
DATABASE_URL="mysql://root:@127.0.0.1:3306/my_database_name"

This file should be ignored by git and should not be committed to your repository. Several other .env files are available to set environment variables in just the right situation:

  • .env: defines the default values of the env vars needed by the application;
  • .env.local: overrides the default values for all environments but only on the machine which contains the file. This file should not be committed to the repository and it's ignored in the test environment (because tests should produce the same results for everyone);
  • .env.<environment> (e.g. .env.test): overrides env vars only for one environment but for all machines (these files are committed);
  • .env.<environment>.local (e.g. .env.test.local): defines machine-specific env var overrides only for one environment. It's similar to .env.local, but the overrides only apply to one environment.

Real environment variables always win over env vars created by any of the .env files. Note that this behavior depends on the variables_order configuration, which must contain an E to expose the $_ENV superglobal. This is the default configuration in PHP.

The .env and .env.<environment> files should be committed to the repository because they are the same for all developers and machines. However, the env files ending in .local (.env.local and .env.<environment>.local) should not be committed because only you will use them. In fact, the .gitignore file that comes with Symfony prevents them from being committed.

Overriding Environment Variables Defined By The System

If you need to override an environment variable defined by the system, use the overrideExistingVars parameter defined by the Symfony\\Component\\Dotenv\\Dotenv::loadEnv, Symfony\\Component\\Dotenv\\Dotenv::bootEnv, and Symfony\\Component\\Dotenv\\Dotenv::populate methods:

use Symfony\Component\Dotenv\Dotenv;

$dotenv = new Dotenv();
$dotenv->loadEnv(__DIR__.'/.env', overrideExistingVars: true);

// ...

This will override environment variables defined by the system but it won't override environment variables defined in .env files.

Configuring Environment Variables in Production

In production, the .env files are also parsed and loaded on each request. So the easiest way to define env vars is by creating a .env.local file on your production server(s) with your production values.

To improve performance, you can optionally run the dump-env Composer command:

# parses ALL .env files and dumps their final values to .env.local.php
$ composer dump-env prod

Dumping Environment Variables without Composer

If you don't have Composer installed in production, you can use the dotenv:dump command instead (available in Symfony Flex <symfony-flex> 1.2 or later). The command is not registered by default, so you must register first in your services:

# config/services.yaml
services:
    Symfony\Component\Dotenv\Command\DotenvDumpCommand: ~

Then, run the command:

# parses ALL .env files and dumps their final values to .env.local.php
$ APP_ENV=prod APP_DEBUG=0 php bin/console dotenv:dump

After running this command, Symfony will load the .env.local.php file to get the environment variables and will not spend time parsing the .env files.

Tip

Update your deployment tools/workflow to run the dotenv:dump command after each deploy to improve the application performance.

Storing Environment Variables In Other Files

By default, the environment variables are stored in the .env file located at the root of your project. However, you can store them in other files in multiple ways.

If you use the Runtime component </components/runtime>, the dotenv path is part of the options you can set in your composer.json file:

{
    // ...
    "extra": {
        // ...
        "runtime": {
            "dotenv_path": "my/custom/path/to/.env"
        }
    }
}

You can also set the SYMFONY_DOTENV_PATH environment variable at system level (e.g. in your web server configuration or in your Dockerfile):

# .env (or .env.local)
SYMFONY_DOTENV_PATH=my/custom/path/to/.env

Finally, you can directly invoke the Dotenv class in your bootstrap.php file or any other file of your application:

use Symfony\Component\Dotenv\Dotenv;

(new Dotenv())->bootEnv(dirname(__DIR__).'my/custom/path/to/.env');

Symfony will then look for the environment variables in that file, but also in the local and environment-specific files (e.g. .*.local and .*.<environment>.local). Read how to override environment variables <configuration-multiple-env-files> to learn more about this.

7.1

The SYMFONY_DOTENV_PATH environment variable was introduced in Symfony 7.1.

Encrypting Environment Variables (Secrets)

Instead of defining a real environment variable or adding it to a .env file, if the value of a variable is sensitive (e.g. an API key or a database password), you can encrypt the value using the secrets management system </configuration/secrets>.

Listing Environment Variables

Use the debug:dotenv command to understand how Symfony parses the different .env files to set the value of each environment variable:

$ php bin/console debug:dotenv

Dotenv Variables & Files
========================

Scanned Files (in descending priority)
--------------------------------------

* ⨯ .env.local.php
* ⨯ .env.dev.local
* ✓ .env.dev
* ⨯ .env.local
* ✓ .env

Variables
---------

---------- ------- ---------- ------
 Variable   Value   .env.dev   .env
---------- ------- ---------- ------
 FOO        BAR     n/a        BAR
 ALICE      BOB     BOB        bob
---------- ------- ---------- ------

# look for a specific variable passing its full or partial name as an argument
$ php bin/console debug:dotenv foo

Additionally, and regardless of how you set environment variables, you can see all environment variables, with their values, referenced in Symfony's container configuration, you can also see the number of occurrences of each environment variable in the container:

$ php bin/console debug:container --env-vars

------------ ----------------- ------------------------------------ -------------
 Name         Default value     Real value                           Usage count
------------ ----------------- ------------------------------------ -------------
 APP_SECRET   n/a               "471a62e2d601a8952deb186e44186cb3"   2
 BAR          n/a               n/a                                  1
 BAZ          n/a               "value"                              0
 FOO          "[1, "2.5", 3]"   n/a                                  1
------------ ----------------- ------------------------------------ -------------

# you can also filter the list of env vars by name:
$ php bin/console debug:container --env-vars foo

# run this command to show all the details for a specific env var:
$ php bin/console debug:container --env-var=FOO

Creating Your Own Logic To Load Env Vars

You can implement your own logic to load environment variables if the default Symfony behavior doesn't fit your needs. To do so, create a service whose class implements Symfony\\Component\\DependencyInjection\\EnvVarLoaderInterface.

Note

If you're using the default services.yaml configuration <service-container-services-load-example>, the autoconfiguration feature will enable and tag this service automatically. Otherwise, you need to register and tag your service </service_container/tags> with the container.env_var_loader tag.

Let's say you have a JSON file named env.json containing your environment variables:

{
    "vars": {
        "APP_ENV": "prod",
        "APP_DEBUG": false
    }
}

You can define a class like the following JsonEnvVarLoader to populate the environment variables from the file:

namespace App\DependencyInjection;

use Symfony\Component\DependencyInjection\EnvVarLoaderInterface;

final class JsonEnvVarLoader implements EnvVarLoaderInterface
{
    private const ENV_VARS_FILE = 'env.json';

    public function loadEnvVars(): array
    {
        $fileName = __DIR__.\DIRECTORY_SEPARATOR.self::ENV_VARS_FILE;
        if (!is_file($fileName)) {
            // throw an exception or just ignore this loader, depending on your needs
        }

        $content = json_decode(file_get_contents($fileName), true);

        return $content['vars'];
    }
}

That's it! Now the application will look for a env.json file in the current directory to populate environment variables (in addition to the already existing .env files).

Tip

If you want an env var to have a value on a certain environment but to fallback on loaders on another environment, assign an empty value to the env var for the environment you want to use loaders:

# .env (or .env.local)
APP_ENV=prod

# .env.prod (or .env.prod.local) - this will fallback on the loaders you defined
APP_ENV=

Accessing Configuration Parameters

Controllers and services can access all the configuration parameters. This includes both the parameters defined by yourself <configuration-parameters> and the parameters created by packages/bundles. Run the following command to see all the parameters that exist in your application:

$ php bin/console debug:container --parameters

In controllers extending from the AbstractController <the-base-controller-class-services>, use the getParameter() helper:

// src/Controller/UserController.php
namespace App\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\Response;

class UserController extends AbstractController
{
    // ...

    public function index(): Response
    {
        $projectDir = $this->getParameter('kernel.project_dir');
        $adminEmail = $this->getParameter('app.admin_email');

        // ...
    }
}

In services and controllers not extending from AbstractController, inject the parameters as arguments of their constructors. You must inject them explicitly because service autowiring </service_container/autowiring> doesn't work for parameters:

# config/services.yaml
parameters:
    app.contents_dir: '...'

services:
    App\Service\MessageGenerator:
        arguments:
            $contentsDir: '%app.contents_dir%'
<!-- 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">

    <parameters>
        <parameter key="app.contents_dir">...</parameter>
    </parameters>

    <services>
        <service id="App\Service\MessageGenerator">
            <argument key="$contentsDir">%app.contents_dir%</argument>
        </service>
    </services>
</container>
// config/services.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;

use App\Service\MessageGenerator;

return static function (ContainerConfigurator $container): void {
    $container->parameters()
        ->set('app.contents_dir', '...');

    $container->services()
        ->get(MessageGenerator::class)
            ->arg('$contentsDir', '%app.contents_dir%');
};

If you inject the same parameters over and over again, use the services._defaults.bind option instead. The arguments defined in that option are injected automatically whenever a service constructor or controller action defines an argument with that exact name. For example, to inject the value of the kernel.project_dir parameter <configuration-kernel-project-directory> whenever a service/controller defines a $projectDir argument, use this:

# config/services.yaml
services:
    _defaults:
        bind:
            # pass this value to any $projectDir argument for any service
            # that's created in this file (including controller arguments)
            $projectDir: '%kernel.project_dir%'

    # ...
<!-- 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>
        <defaults autowire="true" autoconfigure="true" public="false">
            <!-- pass this value to any $projectDir argument for any service
                 that's created in this file (including controller arguments) -->
            <bind key="$projectDir">%kernel.project_dir%</bind>
        </defaults>

        <!-- ... -->
    </services>
</container>
// config/services.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;

return static function (ContainerConfigurator $container): void {
    $container->services()
        ->defaults()
            // pass this value to any $projectDir argument for any service
            // that's created in this file (including controller arguments)
            ->bind('$projectDir', '%kernel.project_dir%');

    // ...
};

Read the article about binding arguments by name and/or type <services-binding> to learn more about this powerful feature.

Finally, if some service needs access to lots of parameters, instead of injecting each of them individually, you can inject all the application parameters at once by type-hinting any of its constructor arguments with the Symfony\\Component\\DependencyInjection\\ParameterBag\\ContainerBagInterface:

// src/Service/MessageGenerator.php
namespace App\Service;

// ...

use Symfony\Component\DependencyInjection\ParameterBag\ContainerBagInterface;

class MessageGenerator
{
    public function __construct(
        private ContainerBagInterface $params,
    ) {
    }

    public function someMethod(): void
    {
        // get any container parameter from $this->params, which stores all of them
        $sender = $this->params->get('mailer_sender');
        // ...
    }
}

Using PHP ConfigBuilders

Writing PHP config is sometimes difficult because you end up with large nested arrays and you have no autocompletion help from your favorite IDE. A way to address this is to use "ConfigBuilders". They are objects that will help you build these arrays.

Symfony generates the ConfigBuilder classes automatically in the kernel build directory <configuration-kernel-build-directory> for all the bundles installed in your application. By convention they all live in the namespace Symfony\Config:

// config/packages/security.php
use Symfony\Config\SecurityConfig;

return static function (SecurityConfig $security): void {
    $security->firewall('main')
        ->pattern('^/*')
        ->lazy(true)
        ->security(false);

    $security
        ->roleHierarchy('ROLE_ADMIN', ['ROLE_USER'])
        ->roleHierarchy('ROLE_SUPER_ADMIN', ['ROLE_ADMIN', 'ROLE_ALLOWED_TO_SWITCH'])
        ->accessControl()
            ->path('^/user')
            ->roles('ROLE_USER');

    $security->accessControl(['path' => '^/admin', 'roles' => 'ROLE_ADMIN']);
};

Note

Only root classes in the namespace Symfony\Config are ConfigBuilders. Nested configs (e.g. \Symfony\Config\Framework\CacheConfig) are regular PHP objects which aren't autowired when using them as an argument type.

Note

In order to get ConfigBuilders autocompletion in your IDE/editor, make sure to not exclude the directory where these classes are generated (by default, in var/cache/dev/Symfony/Config/).

Keep Going!

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

  • /forms
  • /doctrine
  • /service_container
  • /security
  • /mailer
  • /logging

And all the other topics related to configuration:

configuration/*