Elasticsearch-PHP supports logging, but it is not enabled by default for performance reasons. If you wish to enable logging, you need to select a logging implementation, install it, then enable the logger in the Client. The recommended logger is Monolog, but any logger that implements the PSR/Log interface will work.

You might have noticed that Monolog was suggested during installation. To begin using Monolog, add it to your composer.json:

{
    "require": {
        ...
        "elasticsearch/elasticsearch" : "~5.0",
        "monolog/monolog": "~1.0"
    }
}

And then update your composer installation:

php composer.phar update

Once Monolog (or another logger) is installed, you need to create a log object and inject it into the client:

use Monolog\Logger;
use Monolog\Handler\StreamHandler;

$logger = new Logger('name');
$logger->pushHandler(new StreamHandler('path/to/your.log', Logger::WARNING));

$client = ClientBuilder::create()       // Instantiate a new ClientBuilder
            ->setLogger($logger)        // Set your custom logger
            ->build();                  // Build the client object