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

        $node
            ->addDefaultsIfNotSet()
            ->fixXmlConfig('hostname')
            ->children()
                ->scalarNode('connection_id')->defaultNull()->end()
                ->arrayNode('hostnames')
                    ->prototype('scalar')->end()
                    ->defaultValue(array('%doctrine_cache.couchbase.hostnames%'))
                ->end()
                ->scalarNode('username')->defaultNull()->end()
                ->scalarNode('password')->defaultNull()->end()
                ->scalarNode('bucket_name')->defaultValue('doctrine_cache')->end()
            ->end()
        ;

        return $node;
    }