doctrine:
    dbal:
        default_connection: db1
        connections:
            db1:
                driver:   pdo_mysql
                host:     "%database_host2%"
                port:     "%database_port2%"
                dbname:   "%database_name2%"
                user:     "%database_user2%"
                password: "%database_password2%"
                charset:  UTF8
            db2:
                driver:   pdo_mysql
                host:     "%database_host%"
                port:     "%database_port%"
                dbname:   "%database_name%"
                user:     "%database_user%"
                password: "%database_password%"
                charset:  UTF8
    orm:
        default_entity_manager: em1
        entity_managers:
            em1:
                connection: db1
                mapping:
                    FirstBundle: ~
            em2:
                connection: db2
                mappings:
                    SecondBundle: ~

[SymfonyComponentConfigDefinitionExceptionInvalidConfigurationException]
  The attribute "name" must be set for path "doctrine.orm.entity_managers.em2.mappings".