I think this is caused by the special logic in the Configuration class that wraps a string into an array with 1 element when getting a string in trusted_hosts. This logic does not currently check whether the string it receives is an env placeholder.

Thank you.

Here is the code you reference

So this issue is specifically for trusted_hosts.

Well, we could have similar issues in other places doing some logic in beforeNormalization.
Custom normalization logic is not automatically aware of env placeholders (precisely because it is custom logic)

see #27683, #37836, #40654 :)

i think #40654 (comment) is the ideal solution

To my understanding, this fails because "json" declares returning "string|int|bool|...|array".
But the logic in Config considers that such a return-type is not compatible with a config option that accepts only "array".
I think this logic is too restrictive and that it should be fixed.

json declares type array|null.

The issue is ifString then array($str) during config normalization. The env placeholder technically matches as such, but then from the env type POV we see array(array|null) for path trusted_hosts.0

The way I see it, we are using too many normalisations. The ifString then array($str) should be removed.

I agree we're trying to be too smart with these shortcuts.
At least here we can check if the value is an env placeholder, and not wrap it when yes.

If we dont convert a string to an array, we will get the following exception:

A dynamic value is not compatible with a "Symfony\Component\Config\Definition\PrototypedArrayNode" node type at path "framework.trusted_hosts".

it inherits

for prototyped arrays we can allow array-typed placeholders 👍 In this regard i agree with @nicolas-grekas more or less that we can loosen it a bit. Stricly spoken the env doesnt tell us the expected child prototype (eg. string[]) nor can we be compatible with minNumberOfElements. I really do think it should be restricted to array envs only though.

At least here we can check if the value is an env placeholder, and not wrap it when yes

By making ifString() opt-out from envs? eg. #40654 (comment) (maybe via a ifString(true) migration path?)

The ifString then array($str) should be removed.

What's the proposal ... case by case? Deprecate beforeNorm() as a whole? The above?

another issue is $config['prototyped_node'] will start giving strings at compile-time ...

I don't think we should deprecated beforeNormalization. This hook is useful when wanting to provide BC layer. And it also allows doing custom normalizations when needed.
However, we should potentially deprecated some places doing such custom normalizations when removing them would allow supporting env placeholders in the node.

potentially deprecated some places

the "some places" is exactly what started bugging me in #29270 (comment) 😅 but perhaps exposing $isEnv works after all.

Hey, thanks for your report!
There has not been a lot of activity here for a while. Is this bug still relevant? Have you managed to find a workaround?

Relevant for me. But my case is about allowPlaceholders(): false
Found that It restricts specification of emails in mailer.envelope.recipients via env variable

Relevant to me too; And the documentation at https://symfony.com/doc/current/configuration/env_var_processors.html#built-in-environment-variable-processors is still wrong, as far as I understand ...

Hey, thanks for your report!
There has not been a lot of activity here for a while. Is this bug still relevant? Have you managed to find a workaround?

Friendly reminder that this issue exists. If I don't hear anything I'll close this.

I haven't seen any new developments on this, I would still like to see it.

still need this

same here, i need a solution to this. Thanks

same too me

same too

Hey, thanks for your report!
There has not been a lot of activity here for a while. Is this bug still relevant? Have you managed to find a workaround?

I would like to see a solution to convert environment variables into arrays without custom code, just writing configurations.

this works form me (symfony 4.4) :

# env
PRIVATE_PROJECTS="'test.localhost', 'test1.localhost'"

# security.yaml :
- { path: ^/.*, allow_if: "is_authenticated() || request.getHost() not in [%env(string:PRIVATE_PROJECTS)%]" }

hope this will help ;)

Same error with symfony/mailer recipients field

A dynamic value is not compatible with a "Symfony\Component\Config\Definition\PrototypedArrayNode" node type at path "framework.mailer.envelope.recipients".

Same with framework.lock. I'm trying to pass an array of memcached servers, but it not work.
MEMCACHE_SERVERS='memcached://m1.docker:11211,memcached://m2.docker:11211'
or
MEMCACHE_SERVERS="['memcached://m1.docker:11211','memcached://m2.docker:11211']"
not working

The lock memcache store looks following if I'm passing csv:

-store: Symfony\Component\Lock\Store\MemcachedStore {#22171 ▼
    -memcached: Memcached {#23004 ▼
      servers: array:1 [▼
        0 => array:3 [▼
          "host" => "m1.docker:11211,memcached"
          "port" => 11211
          "type" => "TCP"
        ]
      ]
      options: {▶}
    }
    -initialTtl: 300
    -useExtendedReturn: null
  }

and exception Invalid type for path "framework.lock.resources.default.0". Expected one of "bool", "int", "float", "string", but got "array" if I'm passing array in .ENV and trying to env processor as "json" or "array". As I understand it is due env-vars processors loads after framework configuration parsing.

Custom solution 1 via Extension:

Solved it via custom extension. Created parameter and then reused it in the yaml file. Correct me if it's bad practice, but it's only way I have found how to solve it for me.

    public function prepend(ContainerBuilder $container): void
    {
        $envName = 'MEMCACHE_SERVERS';

        $serversAsCsv = getenv($envName);
        
        if (empty($serversAsCsv)) {
            throw new LogicException(sprintf('Check that %s env is set and not empty', $envName));
        }

        $hostsList = str_getcsv($serversAsCsv, ',', '"', PHP_VERSION_ID >= 70400 ? '' : '\\');

        $container->setParameter('cache.memcached.servers', $hostsList);
    }

Custom solution 2 via framework.php:

<?php

use Symfony\Config\FrameworkConfig;

return static function (FrameworkConfig $framework): void {
    $framework->lock()
        ->resource('default', explode(',', getenv('MEMCACHE_SERVERS_2')))
    ;
};

I tried with a Extension and the prepend method, but it seems that at this point the .env file is not loaded yet.

So for the mailer config i just did not use the framework.mailer.envelope.recipients config but wrote a dedicated Listener for the onMessage event that gets the ENV var injected and will transform it to an array.

...
class MailerCatchallListener implements EventSubscriberInterface
{
    /**
     * @var null|Address[]
     */
    private ?array $recipients = null;
    public function __construct(?string $recipients)
    {
        if($recipients) {
            $recipientsArray = explode(',', $recipients);
            $this->recipients = Address::createArray($recipientsArray);
        }
    }

    public function onMessage(MessageEvent $event): void
    {
        if ($this->recipients) {
            $event->getEnvelope()->setRecipients($this->recipients);
        }
    }

    public static function getSubscribedEvents(): array
    {
        return [
            // framework.mailer.catchall_recipients will override
            MessageEvent::class => ['onMessage', -254],
        ];
    }
}

App\Listener\MailerCatchallListener:
  arguments:
    $recipients: '%env(string:MAILER_CATCHALL_RECIPIENTS)%'

Would still be handy though to be able to use the FrameworkBundle config option.

@ivoba, I suppose, the mine suggestions not worked well cause I forgot to mention that we force to use putenv in bootstrap (bad practice, but as it is). It was long ago when started to use that, but as I remember this is key moment why my code works. Correct me someone, please, if I'm wrong.

$dontEnv = (new Dotenv());
// Nicolas Grekas: "Injecting variables via dependency injection, that's the recommended way. i.e. code shouldn't care where the value comes from."
// https://github.com/symfony/symfony/issues/35388#issuecomment-576027130
$dontEnv->usePutenv(true); // <---- THIS ONE. By default it is turn off
$dontEnv->bootEnv(dirname(__DIR__).'/.env');

Why can't trusted_hosts just be handled like trusted_headers? They are also just a list of strings, right?

Edit: ok, this causes other problems because of the dynamic value check and ArrayNode not allowing placeholders.

It would be really helpful, if trusted_hosts could be set to an array using an env variable though.

I'm facing this issue too on a Symfony 6.4 app. Is there still no way to pass an array parsed from en environment variable to properties framework.trusted_proxies and framework.trusted_hosts?

Using the JSON trick (e.g. trusted_hosts: '%env(json:TRUSTED_HOSTS)%') still triggers the following error:
Invalid type for path "framework.trusted_hosts.0". Expected one of "bool", "int", "float", "string", but got "array".

Instead, I altered my index.php file to add the following to it, but it feels hacky:
(Variables are made available in $_SERVER earlier thanks to Dotenv)

if ($trustedProxies = $_SERVER['TRUSTED_PROXIES'] ?? false) {
    Request::setTrustedProxies(explode(',', $trustedProxies), Request::HEADER_X_FORWARDED_FOR | Request::HEADER_X_FORWARDED_PORT | Request::HEADER_X_FORWARDED_PROTO);
}

if ($trustedHosts = $_SERVER['TRUSTED_HOSTS'] ?? false) {
    Request::setTrustedHosts(explode(',', $trustedHosts));
}

Up, still not able to use env var to populate trusted_proxy configuration.

This behaviour is not documented anywhere, and the other "trusted_" configuration works fine with env vars.

I'm not expert in the core of the symfony framework, but the fact that the custom logic to validate the input is done before the environment resolution breaks the ability to use env for this specific configuration, and break the consistency in configurability.

So, this bug is still relevant :)

Fixed by #58161 actually.

Oh fine, that closes a 3.5years old bug :), thank you @nicolas-grekas 👍

@nicolas-grekas is there another ticket for a generic solution or is it a wont-fix?

i was hoping to be able to parse all kind of variables into arrays. i tried to configure the admin_recipients of the notifier with an environment variable which brought me to this ticket.

also other projects like a2lix/TranslationFormBundle#349 would depend on a more generic solution.

related symfony issues/PRs:

• [DI] Preserve placeholder exception for dynamic arrays #29270
• run-time json encoded environment variable string does not work in security.yml #27683

No generic solution is possible unfortunately: the way the config defines or checks the passed values requires special handling for env vars.
It's always possible to contribute the require changes to make env var supported where that'd make sense.