Why is PHP unable to write impressions back to Redis throwing error "NOAUTH Authentication required"?

 Problem

Using PHP SDK, Redis and Split Synchronizer setup, when SDK code calls getTreatment function, an exception occurred:

Fetching item ** SPLITIO.split.test ** from cache getTreatment method is throwing exceptions NOAUTH Authentication required.

 Root cause

Redis instance requires authentication, the PHP code is missing the password parameter in the Redis configuration structure.

$options = ['prefix' => ''];
$sdkConfig = array(
                'cache' => array('adapter' => 'predis', 
                                'parameters' => $parameters, 
                                'options' => $options
                                )
            );

 Solution

Since the Split PHP SDK uses predis library, we can add the password parameter to the configuration structure:

$options = [
                'prefix' => '',
                'parameters' => [
                    'password' => 'REDISPASSWORD'
                ],
            ];
$sdkConfig = array(
                'cache' => array('adapter' => 'predis', 
                                'parameters' => $parameters, 
                                'options' => $options
                                )
            );