private function addPredisNode()
    {
        $builder = new TreeBuilder('predis');
        $node    = $this->getRootNode($builder, 'predis');

        $node
            ->addDefaultsIfNotSet()
            ->children()
                ->scalarNode('client_id')->defaultNull()->end()
                ->scalarNode('scheme')->defaultValue('tcp')->end()
                ->scalarNode('host')->defaultValue('%doctrine_cache.redis.host%')->end()
                ->scalarNode('port')->defaultValue('%doctrine_cache.redis.port%')->end()
                ->scalarNode('password')->defaultNull()->end()
                ->scalarNode('timeout')->defaultNull()->end()
                ->scalarNode('database')->defaultNull()->end()
                ->arrayNode('options')
                  ->useAttributeAsKey('name')
                  ->prototype('scalar')->end()
                ->end()
            ->end()
        ;

        return $node;
    }