def service_is_up(service):
    """Check whether a service is up based on last heartbeat."""
    last_heartbeat = service['updated_at'] or service['created_at']
    # Timestamps in DB are UTC.
    elapsed = total_seconds(utcnow() - last_heartbeat)
    LOG.warning("abs(elapsed): %s, FLAGS.service_down_time: %s" % (abs(elapsed), FLAGS.service_down_time))
    return abs(elapsed) <= FLAGS.service_down_time