Acquia Auth to Selenium Client for Update (post)

auth.php

    /**
     * Update a Solarium client object for an 'Update' query
     * with acquia authentication
     *
     * Needs to add following to, Solarium\Plugin\BufferedAdd\BufferedAdd.php:flush()
     * after addDocuments call, so all flush queries get auth cookies:
     *
     *  $sdsSolrBase = new SolrBase();
     *  $this->client = $sdsSolrBase->clientAttachAuth($this->client, $this->updateQuery);
     *
     * @param $client
     *
     * @param $update
     *
     * @return $client
     */
    function clientAttachAuth($client, $update) {
        $request = $client->createRequest($update);
        $endpoint = $client->getEndpoint();

        // Acquia bit
        $signature = new Signature($endpoint->getKey());
        $acquia_solr_hmac = $signature->generate($request->getRawData());
        $acquia_solr_time = $signature->getRequestTime();
        $acquia_solr_nonce = $signature->getNonce();

        // Add cookies to request through Solarium adapter Zend2Http
        $client->setAdapter('Solarium\Core\Client\Adapter\Zend2Http');
        $zendHttp = $client->getAdapter()->getZendHttp();
        $zendHttp->addCookie('acquia_solr_time', $acquia_solr_time);
        $zendHttp->addCookie('acquia_solr_nonce', $acquia_solr_nonce);
        $zendHttp->addCookie('acquia_solr_hmac', $acquia_solr_hmac);

        return $client;
    }