silverstripe-environmentcheck/code/checks/SolrIndexCheck.php

<?php

/**
 * Check the availability of all Solr indexes of given class.
 *
 * If there are no indexes of given class found, the returned status will still be "OK".
 */
class SolrIndexCheck implements EnvironmentCheck {
	/**
	 * @var null|string
	 */
	protected $indexClass;

	/**
	 * @param string $indexClass Limit the index checks to the specified class and all its subclasses.
	 */
	function __construct($indexClass = null) {
		$this->indexClass = $indexClass;
	}

	/**
	 * @inheritdoc
	 *
	 * @return array
	 */
	function check() {
		$brokenCores = array();

		if (!class_exists('Solr')) {
			return array(
				EnvironmentCheck::ERROR,
				'Class `Solr` not found. Is the fulltextsearch module installed?'
			);
		}

		$service = Solr::service();
		foreach (Solr::get_indexes($this->indexClass) as $index) {
			$core = $index->getIndexName();
			if (!$service->coreIsActive($core)) {
				$brokenCores[] = $core;
			}
		}

		if (!empty($brokenCores)) {
			return array(
				EnvironmentCheck::ERROR,
				'The following indexes are unavailable: ' . implode($brokenCores, ', ')
			);
		}

		return array(EnvironmentCheck::OK, 'Expected indexes are available.');
	}
}