Spring Boot Actuator + Micrometer + Prometheus

dependencies {
    implementation("org.springframework.boot:spring-boot-starter-actuator")
    implementation("io.micrometer:micrometer-registry-prometheus")
}

management:
  endpoints:
    web:
      exposure:
        include: health,info,metrics,prometheus,loggers
      base-path: /actuator
  endpoint:
    health:
      show-details: when_authorized  # подробности только для админа
      probes:
        enabled: true  # для K8s liveness/readiness
  metrics:
    tags:
      application: ${spring.application.name}
      profile: ${spring.profiles.active:default}
  prometheus:
    metrics:
      export:
        enabled: true

# SecurityConfig — actuator открыт для scrape'а Prometheus
# В продакшене лучше отдельный порт (см. ниже)

# Liveness/readiness для K8s
GET /actuator/health/liveness    # "status": "UP" — приложение живо
GET /actuator/health/readiness   # "status": "UP" — готово принимать трафик

# Метрики
GET /actuator/metrics            # список метрик
GET /actuator/metrics/jvm.memory.used  # конкретная метрика
GET /actuator/prometheus         # в формате Prometheus

# Логи
GET /actuator/loggers            # все логгеры и их уровни
POST /actuator/loggers/com.taskflow  # изменить уровень (admin only)

# Info
GET /actuator/info

# HELP jvm_memory_used_bytes The amount of used memory
# TYPE jvm_memory_used_bytes gauge
jvm_memory_used_bytes{application="taskflow",area="heap",id="G1 Eden Space",} 1.2345678E7

# HELP http_server_requests_seconds
# TYPE http_server_requests_seconds summary
http_server_requests_seconds_count{method="GET",outcome="200",status="200",uri="/api/tasks",} 42.0
http_server_requests_seconds_sum{method="GET",outcome="200",status="200",uri="/api/tasks",} 1.234

# HELP hikaricp_connections_active
# TYPE hikaricp_connections_active gauge
hikaricp_connections_active{pool="HikariPool-1",} 3.0

package com.taskflow.metrics;

import io.micrometer.core.instrument.Counter;
import io.micrometer.core.instrument.MeterRegistry;
import io.micrometer.core.instrument.Timer;
import org.springframework.stereotype.Component;

@Component
public class TaskMetrics {
    private final Counter tasksCreated;
    private final Counter tasksDeleted;
    private final Timer taskCreationTimer;

    public TaskMetrics(MeterRegistry registry) {
        this.tasksCreated = Counter.builder("taskflow.tasks.created")
            .description("Total number of tasks created")
            .register(registry);

        this.tasksDeleted = Counter.builder("taskflow.tasks.deleted")
            .description("Total number of tasks deleted")
            .register(registry);

        this.taskCreationTimer = Timer.builder("taskflow.task.creation.time")
            .description("Time to create a task")
            .publishPercentiles(0.5, 0.95, 0.99)
            .register(registry);
    }

    public void incrementCreated() { tasksCreated.increment(); }
    public void incrementDeleted() { tasksDeleted.increment(); }
    public Timer creationTimer() { return taskCreationTimer; }
}

@Service
public class TaskService {
    // ...
    private final TaskMetrics metrics;

    public TaskService(..., TaskMetrics metrics) {
        // ...
        this.metrics = metrics;
    }

    public TaskResponse create(CreateTaskRequest req) {
        return metrics.creationTimer().record(() -> {
            User me = currentUser.get();
            Task task = mapper.toEntity(req);
            task.setOwner(me);
            Task saved = repo.save(task);
            metrics.incrementCreated();  // <-- Counter
            return mapper.toResponse(saved);
        });
    }

    public void delete(Long id) {
        // ...
        repo.delete(task);
        metrics.incrementDeleted();
    }
}

management:
  server:
    port: 9090          # отдельный порт, доступ только изнутри K8s
    address: 127.0.0.1  # слушает только localhost

Тогда /actuator/prometheus доступен на localhost:9090, основной API — на :8080.

# docker-compose.monitoring.yml
services:
  prometheus:
    image: prom/prometheus:latest
    volumes:
      - ./prometheus.yml:/etc/prometheus/prometheus.yml
    ports: ["9090:9090"]

  grafana:
    image: grafana/grafana:latest
    environment:
      GF_SECURITY_ADMIN_PASSWORD: admin
    ports: ["3000:3000"]
    depends_on: [prometheus]

prometheus.yml:

global:
  scrape_interval: 15s

scrape_configs:
  - job_name: 'taskflow'
    metrics_path: '/actuator/prometheus'
    static_configs:
      - targets: ['host.docker.internal:8080']

1. http://localhost:3000 → admin/admin
2. Data Sources → Add → Prometheus → http://prometheus:9090
3. Import dashboard ID 11378 (Spring Boot) — готовые графики

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