[5.8] Use ClusterInterface instead of PredisCluster

[matthew-inamdar]

The issue

There is an issue when running the artisan cache:clear command with a redis cluster using the Predis library:

php artisan cache:clear

Predis\NotSupportedException  : Cannot use 'FLUSHDB' with redis-cluster.

The reason why

There is logic to check whether the connection is using a cluster or single node, which determines how the flush command should be executed. However the condition for this check isn't working correctly.

The current logic checks to see if the connection is an instance of Predis\Connection\Aggregate\PredisCluster, however when I was debugging the error I noticed the instance I got was of Predis\Connection\Aggregate\RedisCluster.

The proposed solution

Both of these classes implement the Predis\Connection\Aggregate\ClusterInterface interface, so by checking if the connection is an instance of this interface instead, the error no longer occurs.

Supporting info

My Redis config in config/database.php is:

'redis' => [
    'client' => 'predis',

    'options' => [
        'cluster' => 'redis',
    ],

    'clusters' => [
        'default' => [
            'parameters' => [
                'host' => '127.0.0.1',
                'password' => null,
                'port' => 6379,
            ],
        ],
    ],

],