config.yml

doctrine:
    dbal:
        #driver:   "%database.driver%"
        driver:   "%database.driver%" # this does not work
        host:     "%database_host%"
        port:     "%database_port%"
        dbname:   "%database_name%"
        user:     "%database_user%"
        password: "%database_password%"
        charset:  UTF8

parameters.yml

# This file is auto-generated during the composer install
parameters:
    database:
        driver: pdo_mysql
    #database_driver: pdo_mysql
    database_host: 127.0.0.1
    database_port: null
    database_name: database
    database_user: user
    database_password: password
    mailer_transport: smtp
    mailer_host: 127.0.0.1
    mailer_user: null
    mailer_password: null
    locale: de
    secret: ThisTokenIsNotSoSecretChangeIt
    debug_toolbar: true
    debug_redirects: false
    use_assetic_controller: true