万字长文：Dropwizard——基于Dropwizard轻松构建轻量级、可观测、生产就绪、集成监控、微服务的Java云原生应用

# config.yml
server:
  applicationConnectors:
    - type: http
      port: 8080
  adminConnectors:
    - type: http
      port: 8081

// 资源类
@GET
@Path("/status")
public ServiceStatus getStatus() {
    return new ServiceStatus("UP", System.currentTimeMillis());
}
// 客户端将收到: {"status":"UP","timestamp":1717020800000}

// 在您的服务中注册一个 Timer
private final Timer processTimer = metrics.timer("data.processing.time");

public void processData(Data data) {
    Timer.Context context = processTimer.time();
    try {
        // ... your business logic
    } finally {
        context.stop(); // 自动记录耗时
    }
}

mvn archetype:generate \
  -DarchetypeGroupId=io.dropwizard.archetypes \
  -DarchetypeArtifactId=java-simple \
  -DarchetypeVersion=4.0.1 \
  -DgroupId=com.example \
  -DartifactId=monitoring-service \
  -Dversion=1.0.0-SNAPSHOT \
  -Dpackage=com.example.monitoring

public class MonitoringConfiguration extends Configuration {
    @NotEmpty
    private String serviceName = "monitoring-service";

    @Valid
    @NotNull
    private DataSourceFactory database = new DataSourceFactory();

    // getters and setters
}

public class DatabaseHealthCheck extends HealthCheck {
    private final ManagedDataSource dataSource;

    public DatabaseHealthCheck(ManagedDataSource dataSource) {
        this.dataSource = dataSource;
    }

    @Override
    protected Result check() throws Exception {
        try (Connection connection = dataSource.getConnection()) {
            if (connection.isValid(1)) {
                return Result.healthy("Database is reachable");
            } else {
                return Result.unhealthy("Database is not valid");
            }
        } catch (Exception e) {
            return Result.unhealthy("Failed to connect to database: " + e.getMessage());
        }
    }
}

public class DataProcessingService {
    private final Meter packetsReceived;
    private final Timer processingTime;

    public DataProcessingService(MetricRegistry metrics) {
        this.packetsReceived = metrics.meter("packets.received");
        this.processingTime = metrics.timer("processing.time");
    }

    public void handlePacket(Packet packet) {
        packetsReceived.mark(); // 计数+1
        Timer.Context context = processingTime.time();
        try {
            // Simulate processing
            Thread.sleep(packet.getSize() / 10);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        } finally {
            context.stop();
        }
    }
}

public class MonitoringApplication extends Application<MonitoringConfiguration> {
    @Override
    public void initialize(Bootstrap<MonitoringConfiguration> bootstrap) {
        // nothing to do yet
    }

    @Override
    public void run(MonitoringConfiguration config, Environment env) {
        // 1. 初始化数据源
        final ManagedDataSource dataSource = config.getDataSourceFactory()
            .build(env.metrics(), "postgresql");

        // 2. 注册健康检查
        env.healthChecks().register("database", new DatabaseHealthCheck(dataSource));

        // 3. 创建并注册业务服务
        DataProcessingService service = new DataProcessingService(env.metrics());

        // 4. 注册 REST 资源
        env.jersey().register(new MonitoringResource(service));

        // 5. 管理数据源生命周期
        env.lifecycle().manage(dataSource);
    }

    public static void main(String[] args) throws Exception {
        new MonitoringApplication().run(args);
    }
}

@Path("/monitor")
@Produces(MediaType.APPLICATION_JSON)
public class MonitoringResource {
    private final DataProcessingService service;

    public MonitoringResource(DataProcessingService service) {
        this.service = service;
    }

    @POST
    @Path("/packet")
    public Response receivePacket(Packet packet) {
        service.handlePacket(packet);
        return Response.ok().build();
    }
}

# 应用基本信息
serviceName: "edge-metrics-collector"

# 服务器配置
server:
  applicationConnectors:
    - type: http
      port: 8080
  adminConnectors:
    - type: http
      port: 8081

# 数据库配置
database:
  driverClass: org.postgresql.Driver
  user: metrics_user
  password: secret
  url: jdbc:postgresql://db:5432/metrics

# 打包
./mvnw package

# 启动
java -jar target/monitoring-service-1.0.0-SNAPSHOT.jar server config.yml

# 检查健康
curl http://localhost:8081/healthcheck

# 查看指标
curl http://localhost:8081/metrics

FROM eclipse-temurin:17-jre-alpine
COPY target/monitoring-service-*.jar app.jar
EXPOSE 8080 8081
ENTRYPOINT ["java", "-jar", "/app.jar", "server", "/config/config.yml"]

<dependency>
    <groupId>io.prometheus</groupId>
    <artifactId>simpleclient_dropwizard</artifactId>
    <version>0.16.0</version>
</dependency>

CollectorRegistry registry = new CollectorRegistry();
new DropwizardExports(env.metrics()).register(registry);

env.admin().addServlet("prometheus", new MetricsServlet(registry))
    .addMapping("/metrics/prometheus");