Redis cache configuration on Pantheon

Redis provides an alternative caching backend for Drupal, taking that work off the database, which is vital for scaling to a larger number of logged-in users. It also provides a number of other nice features for develoeprs looking to use it to manage queues, or do custom caching of their own.

Particularly, it does a really great job of speeding up the content editing experience for logged in users quite a bit and makes Panopoly/the IPE much, much zippier with very little work.

See the docs here: 

Configuration

1. request that Pantheon enable redis via a help ticket
2. install drupal redis module

3. In settings.php we drop in

   /**
    * Perform web and drush operations on Pantheon
    * see http://helpdesk.getpantheon.com/customer/portal/articles/708588
    */
   if (defined('PANTHEON_ENVIRONMENT')) {
    
     // Use Redis for caching on TEST and LIVE
     if (in_array(PANTHEON_ENVIRONMENT, array('test', 'live'))) {
       $conf['redis_client_interface'] = 'PhpRedis';
       $conf['cache_backends'][] = 'sites/all/modules/contrib/redis/redis.autoload.inc';
       $conf['cache_default_class'] = 'Redis_Cache';
       $conf['cache_prefix'] = array('default' => 'pantheon-redis');
       // Do not use Redis for cache_form (no performance difference).
       $conf['cache_class_cache_form'] = 'DrupalDatabaseCache';
       // Use Redis for Drupal locks (semaphore).
       $conf['lock_inc'] = 'sites/all/modules/contrib/redis/redis.lock.inc';
     }
    
   }

4. to access Pantheon redis, you will need local command line tools.
   this is easiest with homebrew on OS X:

   $ brew install redis

   or you can download at http://redis.io/download for all OSes.

   To install with Docker:
   docker pull shopigniter/redis-cli

   


5. Once install you will need to log in using the credentials from the pantheon dashboard
   to flush the cache on DEV.
   This is useful so that we have a baseline for testing speed gains and debugging. 

   $ redis-cli -h XXX.XXX.XXX.XXX -p XXXX -a xxxxxxxxxxxxxxxxxxxxxxxxxxx
   > flushall
   
   $ docker run -i -t --rm=true shopigniter/redis-cli -h XXX.XXX.XXX.XXX -p XXXX -a xxxxxxxxxxxxxxxxxxxxxxxxxxx
   > flushall

External docs

• http://redis.io/topics/config
• http://helpdesk.getpantheon.com/customer/portal/articles/401317-understanding-redis-cache

Related articles

• Page:
  Conditional Caching - DEPRECATED
• Page:
  Redis cache configuration on Pantheon
• Page:
  Varnish Installation/Configuration