RatioGaugeHealthCheck.java

/**
 * Gauge-based health check that will return unhealthy if the
 * gauge value falls below the threshold
 */
public class RatioGaugeHealthCheck extends HealthCheck {

    private final RatioGauge gauge;
    private final double threshold;
    private final String name;

    public RatioGaugeHealthCheck(String name, RatioGauge gauge, double threshold) {
        this.name = requireNonNull(name);
        this.gauge = requireNonNull(gauge);
        this.threshold = threshold;

        checkArgument(!name.isEmpty(), "name must be specified");
        checkArgument(threshold >= 0 && threshold <= 1, String.format("threshold out of range: [%.02f]", threshold));
    }

    public String getName() {
        return name;
    }

    @Override
    protected Result check() throws Exception {
        final Double value =  gauge.getValue();
        if (Double.isNaN(value)) {
            return Result.healthy("Unable to determine health. Gauge value is Double.NaN. The gauge may have no data or there may be a problem.");
        } else if ( value >= threshold ) {
            return Result.healthy();
        } else {
            return Result.unhealthy("Healthcheck [%s] value of %.02f is below threshold %.02f", name, value, threshold);
        }
    }
}

Usage.java

    // mark these meters on success/failure
    private static final Meter PUBLISH_STATE_OK = new Meter();
    private static final Meter PUBLISH_STATE_NOT_OK = new Meter();
    private static final RatioGauge PUBLISH_STATE_GAUGE = new RatioGauge() {
        @Override
        protected Ratio getRatio() {
            final double numerator = PUBLISH_STATE_OK.getOneMinuteRate();
            final double denominator = numerator + PUBLISH_STATE_NOT_OK.getOneMinuteRate();
            return Ratio.of(numerator, denominator);
        }
    };
    
    
    // register a health check
    
        final RatioGaugeHealthCheck check =
            new RatioGaugeHealthCheck("publish-success", PUBLISH_STATE_GAUGE, configuration.getPublishHealthThreshold());
        environment.healthChecks().register(check.getName(), check);