The container can accept the following variables:
$ACTIVITI_HOST: Activiti host address (default: localhost)
$ACTIVITI_USER: Activiti user name (default: user)
$ACTIVITI_PASSWORD: Activiti password (default: changeme)
$DB_HOST: Database host address (default: localhost)
$RACK_ENV: Ruby runtime environment (available options: development, production, test; default: development)