Enable 2 factor module configuration via environment variables about 2fa

[scheb]

Feature released with version 5.5.0.

[Spomky]

What about the bool env processor ?
https://symfony.com/doc/current/configuration/env_var_processors.html#built-in-environment-variable-processors

scheb_two_factor:
  email:
    enabled: '%env(bool:ENABLE_2FA)%'

[aturki]

That was my first approach indeed. But it seems that Symfony is delaying the evaluation of these variables until later in the container's construction process.
Since we are actually executing code in the bundle's configuration it's not possible to use the processors ref

[scheb]

Ok, I just learned something new. Environment variables are only replaced after the container building phase and are represented by their placeholder string until then (which is in our case always evaluating to true).

When you need the environment variable value during container building, you have to take care of transforming the variables. resolveEnvPlaceholders (as suggested in your PR) seems to be the way to go: symfony/symfony#21420 (comment)