New in Symfony 3.4: Advanced environment variables
September 22, 2017
•
Published by
Javier Eguiluz
Warning: This post is about an unsupported Symfony version. Some of this information may be out of date. Read the most recent Symfony Docs.
Symfony 4 will promote and leverage environment variables to configure some parts of the applications. In Symfony 3.4 we're working hard to make that fully possible. The last big hurdle was that environment variables are always transformed into strings. That's a big problem when using PHP 7.1 type-hints:
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public function connect(string hostname, int port)
{
// ...
}If the value of the port argument is obtained through an env var, the
application won't work because the argument will be a string instead of the
expected integer:
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parameters:
app.connection.port: '%env(DATABASE_PORT)%'In Symfony 3.4 we improved the processing of environment variables to support type casting. When referencing an env var, you can now set the type you want its value converted to:
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parameters:
# roughly equivalent to "(int) getenv('DATABASE_PORT')"
app.connection.port: '%env(int:DATABASE_PORT)%'We included support for the usual bool:, int:, float: and
string: casting. But we didn't stop there! We also added some utilities to
perform the most common operations related to env vars (and you can combine
them all).
The resolve: processor replaces container parameter names by their values:
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parameters:
project_dir: '/foo/bar'
env(DB): 'sqlite://%%project_dir%%/var/data.db'
db_dsn: '%env(resolve:DB)%'The file: processor gets the contents of the given file and the json:
processor decodes the given contents into a PHP array, so you can combine them
to get the secrets stored in some file:
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parameters:
env(SECRETS_FILE): '/etc/secure/example.com/secrets.json'
app.secrets: '%env(json:file:SECRETS_FILE)%'The base64: processor decodes the given base64 content and const: allows
you to refer to any PHP constant:
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parameters:
env(SOME_VALUE): 'NWE3OWExYzg2NmVmZWY5Y2ExODAwZjk3MWQ2ODlmM2U='
app.some_value: '%env(base64:SOME_VALUE)%'
env(NUM_ITEMS): 'App\Entity\BlogPost::NUM_ITEMS'
app.num_items: '%env(const:NUM_ITEMS)%'Last but not least, you can define your own processors to manipulate the
content of the environment variables before using them. To do so, define a
service implementing the new EnvVarProcessorInterface and tag it with
container.env_var_processor.
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Comments are closed.
To ensure that comments stay relevant, they are closed for old posts.
Also `container.env_provider` is actually `container.env_var_processor` :)
Like `%env(myDecoder:API_PASSWORD)%`, which will decrypt the environment value into something usable.
class MyDecoder implements EnvironmentOperator {
public function resolve(string $value): string {
// magic stuff for decryption
return $value;
}
}
What about former yaml arrays like locales: [de,en]? Currently they are strings when using env vars.
but good to hear at all. Now i can cast APP_DEBUG(int) to bool. Cool.
```
bind:
$dbSecret: '@=parameter("app.secrets")["dbSecret"]'
```