configure memcached

//..

'default' => env('CACHE_DRIVER', 'memcached'),

// ...

'memcached' => [
    'driver' => 'memcached',
    'persistent_id' => 'memcached_pool_id',
    'sasl' => [
        config('memcachier.MEMCACHIER_USERNAME'),
        config('memcachier.MEMCACHIER_PASSWORD'),
    ],
    'options' => [
        // some nicer default options
        // - nicer TCP options
        Memcached::OPT_TCP_NODELAY => TRUE,
        Memcached::OPT_NO_BLOCK => FALSE,
        // - timeouts
        Memcached::OPT_CONNECT_TIMEOUT => 2000,    // ms
        Memcached::OPT_POLL_TIMEOUT => 2000,       // ms
        Memcached::OPT_RECV_TIMEOUT => 750 * 1000, // us
        Memcached::OPT_SEND_TIMEOUT => 750 * 1000, // us
        // - better failover
        Memcached::OPT_DISTRIBUTION => Memcached::DISTRIBUTION_CONSISTENT,
        Memcached::OPT_LIBKETAMA_COMPATIBLE => TRUE,
        Memcached::OPT_RETRY_TIMEOUT => 2,
        Memcached::OPT_SERVER_FAILURE_LIMIT => 1,
        Memcached::OPT_AUTO_EJECT_HOSTS => TRUE,

    ],
    'servers' => array_map(function($s) {
        $parts = explode(":", $s);
        return [
            'host' => $parts[0],
            'port' => $parts[1],
            'weight' => 100,
        ];
      }, explode(",", config('memcachier.MEMCACHIER_SERVERS')))
],