HealthIndicatorWithMetric.java

/**
 * An extension of the Spring Boot Actuator health indicator. Implementing this abstract class will give you both a
 * health check on /health, as well as a Prometheus metric representing the health check on /metrics (1 for up, 0 for
 * down).
 * <p>
 * Note: Spring health indicators only run when /health is called.
 */
abstract class HealthIndicatorWithMetric implements HealthIndicator {
    private Logger log = LoggerFactory.getLogger(HealthIndicatorWithMetric.class);

    // Micrometer won't update a gauge metric unless you use an atomic number
    private AtomicInteger healthy = new AtomicInteger(0);

    private final String metricName;

    public HealthIndicatorWithMetric(MeterRegistry meterRegistry, String metricName) {
        this.metricName = metricName;
        meterRegistry.gauge(metricName, List.of(), healthy);
    }

    @Override
    public final Health health() {
        try {
            Health health = performHealthCheck();

            if (Status.UP.equals(health.getStatus())) {
                healthy.set(1);
            } else {
                healthy.set(0);
            }

            return health;
        } catch (Exception e) {
            log.error(metricName + " health check threw unhandled error", e);
            healthy.set(0);
            return Health.down().withException(e).build();
        }
    }

    public abstract Health performHealthCheck();
}