Symfony Validation / Caching ClassMetadata information using Doctrine FilesystemCache.

config.yml

framework:
    validation:      { enable_annotations: true, cache: validator.mapping.cache.doctrine.filesystem_cache }

services.yml

services:

    cache.doctrine.filesystem_cache:
        class: Doctrine\Common\Cache\FilesystemCache
        arguments: ["%kernel.cache_dir%/validations"]
        public: false
        calls:
            - [setNamespace, ["%validator.mapping.cache.prefix%"]]

    validator.mapping.cache.doctrine.filesystem_cache:
        class: Symfony\Component\Validator\Mapping\Cache\DoctrineCache
        public: false
        arguments: ["@cache.doctrine.filesystem_cache"]