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

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

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';
  }
 
}

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.
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
 
```

Configuration

External docs

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