Deploying symfony to Heroku, get swiftmailer parameters via configvars - symfony

Question

I have deployed my symfony app to Heroku, but I want to configure the swiftmailer component with config_vars provided by Heroku. I already have two of them:
SYMFONY_ENV: prod
CLEARDB_DATABASE_URL: my-connection-string
Now what I would like to do is to decribe swiftmailer credentials in the config_prod.yml:
#config_prod.yml
swiftmailer:
transport: "%env(mail_transport)%"
host: "%env(mail_host)%"
username: "%env(mail_user)%"
password: "%env(mail_password)%"
spool: { type: memory }
I, then, set up the config_vars on Heroku, however when trying to deploy the app I got the following exception.
[Symfony\Component\DependencyInjection\Exception\EnvParameterException]
Incompatible use of dynamic environment variables "mail_transport" found in parameters.
[Symfony\Component\DependencyInjection\Exception\InvalidArgumentException]
Unable to replace alias "swiftmailer.mailer.default.transport.real" with actual definition "%env(mail_transport)%".
[Symfony\Component\DependencyInjection\Exception\ServiceNotFoundException]
You have requested a non-existent service "%env(mail_transport)%".
Script Sensio\Bundle\DistributionBundle\Composer\ScriptHandler::clearCache handling the symfony-scripts event terminated with an exception
If I hardcode the parameters in the config.yml then deploying to Heroku succeeds.
What am I messing up? Thx in advance.

Answer 1

I do not know much about heroku but i know how to get ENV_VAR inside symfony config ;)
inside app/config where your other configs files reside create a new file called parameters.php
<?php
if(isset($_SERVER['AWS_MAILER_HOST']) ){
$container->setParameter('mailer_transport', #$_SERVER['AWS_MAILER_TRANSPORT']);
$container->setParameter('mailer_host', #$_SERVER['AWS_MAILER_HOST']);
$container->setParameter('mailer_username', #$_SERVER['AWS_MAILER_USERNAME']);
$container->setParameter('mailer_password', #$_SERVER['AWS_MAILER_PASSWORD']);
$container->setParameter('mailer_port', #$_SERVER['AWS_MAILER_PORT']);
$container->setParameter('mailer_encryption', #$_SERVER['AWS_MAILER_ENCRYPTION']);
$container->setParameter('mailer_auth_mode', #$_SERVER['AWS_MAILER_AUTH_MODE']);
}
replace all 'AWS_MAILER_...' with your ENVIRONEMENT_VAR
Inside your app/config/config.yml put
imports:
- { resource: parameters.yml }
- { resource: parameters.php } <------------