Full list of configurations

$paramDefaults = array(
    'connectionClass'       => '\Elasticsearch\Connections\GuzzleConnection',
    'connectionFactoryClass'=> '\Elasticsearch\Connections\ConnectionFactory',
    'connectionPoolClass'   => '\Elasticsearch\ConnectionPool\StaticNoPingConnectionPool',
    'selectorClass'         => '\Elasticsearch\ConnectionPool\Selectors\RoundRobinSelector',
    'serializerClass'       => '\Elasticsearch\Serializers\ArrayToJSONSerializer',
    'sniffOnStart'          => false,
    'connectionParams'      => array(),
    'logging'               => false,
    'logObject'             => null,
    'logPath'               => 'elasticsearch.log',
    'logLevel'              => Log\LogLevel::WARNING,
    'traceObject'           => null,
    'tracePath'             => 'elasticsearch.log',
    'traceLevel'            => Log\LogLevel::WARNING,
    'guzzleOptions'         => array(),
    'connectionPoolParams'  => array(
        'randomizeHosts' => true
    ),
    'retries'               => null
);