service.scala

case object ClusterDown

case class ClusterUp(status: String)

trait ElasticSearchService[F[_]] {
  def clusterHealth: F[Either[ClusterDown.type, ClusterUp]]
}

object ElasticSearchService {
  private[this] val log = getLogger.logger

  def impl[F[_] : Sync](client: RestHighLevelClient): ElasticSearchService[F] = new ElasticSearchService[F] {
    override def clusterHealth: F[Either[ClusterDown.type, ClusterUp]] = {
      for {
        request <- Sync[F].pure(new ClusterHealthRequest("question", "answer"))
        response <- Sync[F].delay(client.cluster().health(request, RequestOptions.DEFAULT)) // <- This will make an actual call to ElasticSearch cluster, how do I test this?
          .attempt
          .onError(t => logError(t)) // Is this a good approach to log errors?
      } yield response.map(r => ClusterUp(r.getStatus.toString)).leftMap(_ => ClusterDown)
    }

    private def logError(t: Throwable) = Sync[F].delay(log.error("ElasticSearch error.", t))
  }
}