@Override
    public void unHealth(String reason) {
        log.warn("Health check fails. reason: {}", reason);
        metrics.setValue(1);
    }
HealthCheckMetrics intends to record health status.
oap-server/server-telemetry/telemetry-api/src/main/java/org/apache/skywalking/oap/server/telemetry/api/HealthCheckMetrics.java