Symfony 5.4 environmental variables in services.yaml::parameters - php

Question

Recently I decided to use Symfony 5.4 container in one of the projects to provide some comprehensive DI. It works well as usual, until I tried to use some env vars in services.yaml::parameters section.
Docs state that to bind to an env var I should
# services.yaml
parameters:
my_var: '%env(SOME_ENV_VAR)%'
and it will be resolved from an env var on first call. Okay. I did it this way and here what I get:
echo $container->getParameter('my_var');
// env_b057c2b619f37f36_SOME_ENV_VAR_222ed306d0932595cbdeada438ccbb2a
I do see SOME_ENV_VAR in both $_SERVER and $_ENV. I also tried Dotenv component to be sure I'm not missing something, but vainly. Any env var turns into this sort of env_{hash}_{VAR_NAME}_{hash} pattern.
I'm not using complete Symfony installation, just some spare components. What I'm missing? Should I manually populate each env var on container build stage?
Container is instantiated as follows:
// $_ENV and $_SERVER already contain `SOME_ENV_VAR` here
require_once __DIR__ . '/vendor/autoload.php';
// `use` statements go here
$containerBuilder = new ContainerBuilder();
$loader = new YamlFileLoader(
$containerBuilder,
new FileLocator(implode(DIRECTORY_SEPARATOR, [__DIR__, 'config']))
);
$loader->load('services.yaml');
$containerBuilder->compile();
$container = $containerBuilder;
$my_var = $container->getParameter('SOME_ENV_VAR');
echo $my_var;

Answer 1

Based on your updated snippet, you need to use:
$container->compile(true); // false is the default
The argument is called resolveEnvPlaceholders. I remember it catching me some time ago.
Still find it a bit puzzling that you have $_ENV set but I'll take your word for it.
This is an old test case I dug up that still works:
use Symfony\Component\DependencyInjection\ContainerBuilder;
class Service
{
public function __construct(string $dsn)
{
echo $dsn . "\n";
}
}
$container = new ContainerBuilder();
$container->autowire(Service::class,Service::class)->setPublic(true)
->setArguments([
'%env(DSN)%'
]);
$container->setParameter('my_var','%env(DSN)%');
putenv('DSN=dsn_value');
$container->compile(true);
$service = $container->get(Service::class);
echo $container->getParameter('my_var') . "\n";

Answer 2

The signature for ContainerBuilder::compile() is:
public function compile(bool $resolveEnvPlaceholders = false)
If you do not pass it true, it won't resolve the environment variables' placeholders.
Additionally, there is an issue with your example.
You are calling:
$my_var = $container->getParameter('SOME_ENV_VAR');
But SOME_ENV_VAR is not a container parameter, but an environment variable. The correct call would be:
$my_var = $container->getParameter('my_var');
The whole thing would be:
use Symfony\Component\Config\FileLocator;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Loader\YamlFileLoader;
require_once __DIR__ . '/vendor/autoload.php';
$containerBuilder = new ContainerBuilder();
$loader = new YamlFileLoader(
$containerBuilder,
new FileLocator(implode(DIRECTORY_SEPARATOR, [__DIR__, 'config']))
);
$loader->load(__DIR__ . '/services.yaml');
$containerBuilder->compile(true);
$container = $containerBuilder;
$my_var = $container->getParameter('my_var');
echo $my_var;