Implementing Monitoring and Observability

<dependency>
  <groupId>io.micrometer</groupId>
  <artifactId>micrometer-registry-prometheus</artifactId>
</dependency>

management:
  endpoints.web.exposure.include: prometheus,health
  metrics.tags:
    application: ${spring.application.name}
    env: ${ENV:dev}

<dependency>
  <groupId>io.micrometer</groupId>
  <artifactId>micrometer-tracing-bridge-otel</artifactId>
</dependency>
<dependency>
  <groupId>io.opentelemetry</groupId>
  <artifactId>opentelemetry-exporter-otlp</artifactId>
</dependency>

management:
  tracing:
    sampling.probability: 0.1
  otlp:
    tracing.endpoint: http://collector:4318/v1/traces

@Component
@Endpoint(id = "cache-stats")
public class CacheStatsEndpoint {
  private final CacheManager cm;
  public CacheStatsEndpoint(CacheManager cm) { this.cm = cm; }
  @ReadOperation public Map<String,Object> all() { /* … */ }
  @ReadOperation public Map<String,Object> one(@Selector String name) { /* … */ }
  @WriteOperation public void clear(@Selector String name) { cm.getCache(name).clear(); }
}

management:
  endpoint.health.probes.enabled: true
  health.livenessstate.enabled: true
  health.readinessstate.enabled: true

Counter.builder("api.requests")
  .description("API request count")
  .tags("endpoint", "/orders", "status", "200", "method", "POST")
  .register(registry)
  .increment();