$ cat app/config/config_prod.yml

imports:
    - { resource: config.yml }

#framework:
#    validation:
#        cache: validator.mapping.cache.doctrine.apc
#    serializer:
#        cache: serializer.mapping.cache.apc

#doctrine:
#    orm:
#        metadata_cache_driver: apc
#        result_cache_driver: apc
#        query_cache_driver: apc

monolog:
    handlers:
        main:
            type: stream
            path: '%kernel.logs_dir%/%kernel.environment%.log'
            level: debug
            channels: ['!event']
        console:
            type: console
            channels: ['!event', '!propel']