AWS Elasticache – phpredis – ‘RedisCluster’ not found

Hi there,

I can connect to an AWS Redis cluster and am using the phpredis client as I’ve noted from docs https://github.com/rhubarbgroup/redis-cache?tab=readme-ov-file#scaling and another forum post: https://www.ads-software.com/support/topic/group-flush-not-working-on-aws-elasticache-serverless/

However, when I enable object caching I get an error:

[04-Mar-2024 10:14:32 UTC] PHP Fatal error:  Uncaught Error: Class 'RedisCluster' not found in /bitnami/wordpress/wp-content/object-cache.php:693

Stack trace:

#0 /bitnami/wordpress/wp-content/object-cache.php(536): WP_Object_Cache->connect_using_phpredis()

#1 /bitnami/wordpress/wp-content/object-cache.php(256): WP_Object_Cache->__construct()

#2 /opt/bitnami/wordpress/wp-includes/load.php(856): wp_cache_init()

#3 /opt/bitnami/wordpress/wp-settings.php(131): wp_start_object_cache()

#4 /bitnami/wordpress/wp-config.php(198): require_once('/opt/bitnami/wo...')

#5 /opt/bitnami/wordpress/wp-load.php(50): require_once('/bitnami/wordpr...')

#6 /opt/bitnami/wordpress/wp-blog-header.php(13): require_once('/opt/bitnami/wo...')

#7 /opt/bitnami/wordpress/index.php(17): require('/opt/bitnami/wo...')

#8 {main}

  thrown in /bitnami/wordpress/wp-content/object-cache.php on line 693

I’ve consulted the phpredis docs https://github.com/phpredis/phpredis/blob/develop/INSTALL.md and installed phpredis via:

pecl install redis

enabling said extension within php.ini

Status: Not enabled
Client: phpredis
Drop-in: Not installed
Disabled: No
PhpRedis: Not loaded
Relay: Not loaded
Predis: 2.1.2
Credis: Not loaded
PHP Version: 7.4.27
Plugin Version: 2.5.1
Redis Version: Unknown
Multisite: No
Metrics: Disabled
Metrics recorded: 0
Filesystem: Writable
WP_REDIS_CLIENT: "phpredis"
WP_REDIS_CLUSTER: [
    "tcp://xxx-0001-001.yyy.zzz.euw1.cache.amazonaws.com:6379?alias=node-01",
    "tcp://xxx-0001-002.yyy.zzz.euw1.cache.amazonaws.com:6379?alias=node-02"
]
WP_REDIS_PLUGIN_PATH: "/bitnami/wordpress/wp-content/plugins/redis-cache"
Drop-ins: []

define( 'WP_REDIS_CLIENT', 'phpredis' );

define( 'WP_REDIS_CLUSTER', [
    'tcp://xxx-0001-001.yyy.zzz.euw1.cache.amazonaws.com:6379?alias=node-01',
    'tcp://xxx-0001-002.yyy.zzz.euw1.cache.amazonaws.com:6379?alias=node-02',
] );

Any pointers as to what I’m missing? Thanks in advance.