yii\elasticsearch\Connection::populateNodes PHP Method

    protected function populateNodes()
    {
        $node = reset($this->nodes);
        $host = $node['http_address'];
        $protocol = isset($node['protocol']) ? $node['protocol'] : $this->defaultProtocol;
        if (strncmp($host, 'inet[/', 6) === 0) {
            $host = substr($host, 6, -1);
        }
        $response = $this->httpRequest('GET', "{$protocol}://{$host}/_nodes");
        if (!empty($response['nodes'])) {
            $nodes = $response['nodes'];
        } else {
            $nodes = [];
        }
        foreach ($nodes as $key => &$node) {
            // Make sure that nodes have an 'http_address' property, which is not the case if you're using AWS
            // Elasticsearch service (at least as of Oct., 2015). - TO BE VERIFIED
            // Temporary workaround - simply ignore all invalid nodes
            if (!isset($node['http_address'])) {
                unset($nodes[$key]);
            }
            //Protocol is not a standard ES node property, so we add it manually
            $node['protocol'] = $this->defaultProtocol;
        }
        if (!empty($nodes)) {
            $this->nodes = array_values($nodes);
        } else {
            curl_close($this->_curl);
            throw new Exception('Cluster autodetection did not find any active nodes.');
        }
    }