According to the Symfony documentation, env() parameters were introduced in version 3.2, allowing to use environment variables in service container configuration:
# app/config/config.yml doctrine: dbal: host: '%env(DATABASE_HOST)%'
However, when I try using this functionality in Drupal I get an exception stating:
The service XXX has a dependency on a non-existent parameter "env(DATABASE_HOST)"
Looking at the stack trace I only see references to the default
ResolveParameterPlaceholdersPass and not to
I'm using Drupal 8.6.5 which uses symfony/dependency-injection v3.4.20