public function is_server_configured() {

        if (empty($this->config->server_hostname) || empty($this->config->indexname)) {
            return 'No solr configuration found';
        }

        if (!$client = $this->get_search_client(false)) {
            return get_string('engineserverstatus', 'search');
        }

        try {
            if ($this->get_solr_major_version() < 4) {
                // Minimum solr 4.0.
                return get_string('minimumsolr4', 'search_solr');
            }
        } catch (\SolrClientException $ex) {
            debugging('Solr client error: ' . html_to_text($ex->getMessage()), DEBUG_DEVELOPER);
            return get_string('engineserverstatus', 'search');
        } catch (\SolrServerException $ex) {
            debugging('Solr server error: ' . html_to_text($ex->getMessage()), DEBUG_DEVELOPER);
            return get_string('engineserverstatus', 'search');
        }

        return true;
    }