Craft localisation caching error long time listener, first time caller.

I'm having some issues getting localisation setup on my homestead/vagrant craft 2 site. I'm running into issues, I believe, with the craft cache when I try to visit a localised url I have set up. 

I've been following the guide here, but haven't been able to have any luck with it. 

I am using the folder structure in my public folder as follows  

    /public  
      -index.php  
      -.htaccess  
      /es
        -index.php  
        -.htaccess


My config/general.php file is like this,

    define('URI_SCHEME', (isset($_SERVER['HTTPS'] ) ) ? "https://" : 
    "http://");
    define('SITE_URL',    URI_SCHEME.$_SERVER['SERVER_NAME']);
    define('BASEPATH',     realpath(dirname(__FILE__) . '/../'));

    return array(


    '*' =&gt; array(
      'appId' =&gt; 'app',
      'validationKey' =&gt; getenv('VALIDATION_KEY'),
      'devMode' =&gt; true,
      'backupDbOnUpdate' =&gt; false,
      'omitScriptNameInUrls' =&gt; true,

      'siteUrl' =&gt; array(
         'en' =&gt; 'http://example.test/',
         'es' =&gt; 'http://example.test/es/'
      ),
      'cacheMethod' =&gt; getenv('CACHE_METHOD'),

      'environmentVariables' =&gt; array(
        'basePath' =&gt; BASEPATH,
        'siteUrl'  =&gt; SITE_URL

      ),
     ),

    ),
    )


My public/es/index.php file is pointing to the correct craft folder and has a define(CRAFT_LOCALE, 'es'). I'm stuck as how to progress and any pointers or tips are very appreciated
Heres a screen shot of the actual error on example.test/es
My guess is this is the cause:

'cacheMethod' =&gt; getenv('CACHE_METHOD'),


getenv('CACHE_METHOD') is probably returning null because that environment variable isn't being set like you expect or its set to an unknown caching driver.