How to configure a service with a class name defined on an environment variable?

Question

I would like to load a different file/class depending on an environment variable.

I installed "symfony/expression-language" and tried this:

App\Foo\Bar\MyClass:
    class: '@=env("MY_CLASS_NAME")'

Which leads to this error message:

Invalid service "App\Foo\Bar\MyClass": class "@=env("MY_CLASS_NAME")" does not exist.

Is there any other way to load a different class depending on an env variable?

Answer 1

For the record: I don't think what you are doing is a great idea. For the scenario you describe, it would likely make more sense to use different environments, and define the service differently depending on the environment:

services:
    App\Service\ServiceInterface:
        class: App\Service\GoodService

    when@aws:
        App\Service\ServiceInterface:
            class: App\Service\FooService

    when@test:
        App\Service\ServiceInterface:
            class: App\Service\BarService

I don't really see, at the moment, a scenario where it makes sense to let an environment variable hold a class name, and not have that configuration made explicit in your config somewhere. It's not something where infinite configurability works, there is only a finite (and likely small) number of classes that can be used within the domain of your application.

---

But if you still want to do this, it's much simpler that what you are trying. Simply do:

services:
    App\Service\ServiceInterface:
        class: '%env(APP_SERVICE_CLASS)%'

and then:

#.env
APP_SERVICE_CLASS=App\\Service\\BarService

And that's it.

(Just in case: Logically, you'll have "console clear:cache" to rebuild the container after each change in the environment variable)