Monitoring

Implement production monitoring for Spring Boot applications — Micrometer metrics, Prometheus integration, Grafana dashboards, and distributed tracing with Micrometer Tracing.

@Service
@RequiredArgsConstructor
public class OrderMetricsService {

    private final MeterRegistry meterRegistry;

    // Counter: total orders created
    public void recordOrderCreated(String region, String paymentMethod) {
        meterRegistry.counter("orders.created",
            "region", region,
            "payment_method", paymentMethod
        ).increment();
    }

    // Timer: order processing duration
    public void recordOrderProcessingTime(Duration duration, OrderStatus finalStatus) {
        meterRegistry.timer("orders.processing.duration",
            "status", finalStatus.name()
        ).record(duration);
    }

    // Gauge: current pending orders count
    public void registerPendingOrdersGauge(OrderRepository orderRepository) {
        Gauge.builder("orders.pending.count",
                orderRepository,
                repo -> repo.countByStatus(OrderStatus.PENDING))
            .description("Number of orders in PENDING status")
            .register(meterRegistry);
    }

    // Distribution summary: order value distribution
    public void recordOrderValue(BigDecimal amount) {
        meterRegistry.summary("orders.value",
            "currency", "USD"
        ).record(amount.doubleValue());
    }
}

// Usage in service:
@Service
@Timed("order.service.place")  // Auto-times this method
public class OrderService {
    public Order placeOrder(CreateOrderRequest request) {
        long start = System.currentTimeMillis();
        try {
            Order order = processOrder(request);
            metricsService.recordOrderCreated(request.getRegion(), request.getPaymentMethod());
            return order;
        } finally {
            metricsService.recordOrderProcessingTime(
                Duration.ofMillis(System.currentTimeMillis() - start),
                OrderStatus.CONFIRMED);
        }
    }
}

The RED method is the standard for microservice monitoring: Rate (requests per second), Errors (error rate), Duration (latency percentiles). Create a Grafana dashboard with these three metrics for every service. Add USE metrics for infrastructure: Utilization, Saturation, Errors for CPU, memory, and DB connections. These 6 metrics tell you 90% of what you need to know about service health.