docs: def is_cluster_ssh_available(cluster_instances, opts):
      """
      Check if SSH is available on all the instances in a cluster.
      """
      for i in cluster_instances:
          dns_name = get_dns_name(i, opts.private_ips)
          if not is_ssh_available(host=dns_name, opts=opts):
              return False
      else:
          return True