<?php
namespace SalvoCanna\RedisNotificationBundle\DependencyInjection;

use Symfony\Component\Config\Definition\Builder\TreeBuilder;
use Symfony\Component\Config\Definition\ConfigurationInterface;

class Configuration implements ConfigurationInterface
{
    /**
     * {@inheritDoc}
     */
    public function getConfigTreeBuilder()
    {
        $treeBuilder = new TreeBuilder();
        $rootNode = $treeBuilder->root('rnb');
        $rootNode
            ->children()
            ->scalarNode('redis_connection')
            ->defaultValue('snc_redis.default')
            ->info('Redis connection to use')
            ->end();

        return $treeBuilder;
    }
}

<?php

namespace SalvoCanna\RedisNotificationBundle\DependencyInjection;

use Symfony\Component\Config\Definition\Builder\TreeBuilder;
use Symfony\Component\Config\Definition\ConfigurationInterface;

class Configuration implements ConfigurationInterface
{
    /**
     * {@inheritDoc}
     */
    public function getConfigTreeBuilder()
    {
        $treeBuilder = new TreeBuilder();
        $rootNode = $treeBuilder->root('sc_redis_notification_bundle');
        /*$rootNode
            ->children()
            ->scalarNode('notification_class')
            ->cannotBeEmpty()
            ->defaultValue('AppBundle\\Entity\\Notification')
            ->info('Entity for a notification (default: AppBundle\\Entity\\Notification)')
            ->end();
         */

        return $treeBuilder;
    }
}

--- 
+++ 
@@ -1,5 +1,4 @@
 <?php
-
 namespace SalvoCanna\RedisNotificationBundle\DependencyInjection;
 
 use Symfony\Component\Config\Definition\Builder\TreeBuilder;
@@ -13,15 +12,13 @@
     public function getConfigTreeBuilder()
     {
         $treeBuilder = new TreeBuilder();
-        $rootNode = $treeBuilder->root('sc_redis_notification_bundle');
-        /*$rootNode
+        $rootNode = $treeBuilder->root('rnb');
+        $rootNode
             ->children()
-            ->scalarNode('notification_class')
-            ->cannotBeEmpty()
-            ->defaultValue('AppBundle\\Entity\\Notification')
-            ->info('Entity for a notification (default: AppBundle\\Entity\\Notification)')
+            ->scalarNode('redis_connection')
+            ->defaultValue('snc_redis.default')
+            ->info('Redis connection to use')
             ->end();
-         */
 
         return $treeBuilder;
     }
[Config] Set a basic config tree
