java 45 lines · 8 steps

Instrumenting orders with Micrometer in Spring

A Spring service records order metrics using Micrometer counters, summaries, timers, and gauges.

Explained by highlit

Spring Intermediate metrics micrometer observability dependency-injection generics

1@Service
2public class OrderMetricsService {
3 
  private final MeterRegistry registry;
  private final Counter placedOrders;
  private final Counter failedOrders;
7 
  public OrderMetricsService(MeterRegistry registry) {
      this.registry = registry;
      this.placedOrders = Counter.builder("orders.placed")
              .description("Number of successfully placed orders")
              .baseUnit("orders")
              .register(registry);
      this.failedOrders = Counter.builder("orders.failed")
              .description("Number of orders that failed to process")
              .register(registry);
  }
18 
  public void recordPlaced(Order order) {
      placedOrders.increment();
      registry.summary("orders.value", "currency", order.getCurrency())
              .record(order.getTotal().doubleValue());
      registry.counter("orders.items", "channel", order.getChannel())
              .increment(order.getItemCount());
  }
26 
  public void recordFailed(String reason) {
      failedOrders.increment();
      registry.counter("orders.failed.reasons", "reason", reason).increment();
  }
31 
  public <T> T timeCheckout(String paymentProvider, Supplier<T> checkout) {
      return Timer.builder("orders.checkout.duration")
              .tag("provider", paymentProvider)
              .publishPercentiles(0.5, 0.95, 0.99)
              .register(registry)
              .record(checkout);
  }
39 
  public void trackPending(Supplier<Number> pendingCount) {
      Gauge.builder("orders.pending", pendingCount)
              .description("Orders awaiting fulfillment")
              .register(registry);
  }
45}

01 / 01

STEP 01

Walkthrough

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Three takeaways

1Register hot-path counters once at construction and reuse them, but build tagged metrics on demand to avoid cardinality explosions from unbounded tag values.
2Different metric types answer different questions: counters count events, summaries track value distributions, timers measure latency, and gauges sample live state.
3A gauge holds a reference to a supplier rather than a value, so it re-reads the current state each time metrics are scraped.

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