title: redis cache on codeigniter not supported?
body: <p>I'm working on a CI project and I'm trying to learn to use Redis caching, so I followed the instruction from the <a href="https://codeigniter.com/userguide3/libraries/caching.html#redis-caching" rel="nofollow noreferrer">CI documentation</a></p>
  <p>I've already run the Redis server with a command prompt
  <a href="https://i.stack.imgur.com/74KPo.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/74KPo.png" alt="redis-server" /></a></p>
  <p>and I put this in the <code>/application/config/redis.php</code></p>
  <pre><code>$config['socket_type'] = 'tcp'; // 'tcp' or 'unix'
  $config['socket'] = '/var/run/redis.sock'; // in case of 'unix' socket type
  $config['host'] = '127.0.0.1'; // change this to match your amazon redis cluster node endpoint
  $config['password'] = NULL;
  $config['port'] = 6379;
  $config['timeout'] = 0;
  </code></pre>
  <p>and this code in the <code>/application/core/MY_Controller.php</code></p>
  <pre><code>$this-&gt;load-&gt;driver('cache', array('adapter' =&gt; 'redis','backup' =&gt; 'file'));
  var_dump($this-&gt;cache-&gt;redis-&gt;is_supported());
  </code></pre>
  <p>according to the documentation, that's all I need to do to use Redis Caching in CI.. but somehow when I open the page, it only shows <code>bool(false)</code>. what am I doing wrong here?</p>