服务注册与发现

一、服务注册

1.1 配置文件注册

// /etc/consul.d/user-service.json
{
  "service": {
    "id": "user-service-1",
    "name": "user-service",
    "tags": ["primary", "v1"],
    "address": "192.168.1.100",
    "port": 8080,
    "meta": {
      "version": "1.0.0",
      "env": "production"
    },
    "check": {
      "http": "http://192.168.1.100:8080/health",
      "interval": "10s",
      "timeout": "5s"
    }
  }
}

1.2 HTTP API 注册

# 注册服务
curl -X PUT http://localhost:8500/v1/agent/service/register \
  -H "Content-Type: application/json" \
  -d '{
    "ID": "user-service-1",
    "Name": "user-service",
    "Tags": ["primary"],
    "Address": "192.168.1.100",
    "Port": 8080,
    "Check": {
      "HTTP": "http://192.168.1.100:8080/health",
      "Interval": "10s"
    }
  }'

1.3 命令行注册

consul services register -name=user-service \
  -id=user-service-1 \
  -address=192.168.1.100 \
  -port=8080 \
  -tag=primary

二、服务发现

2.1 HTTP API 查询

# 查询所有服务
curl http://localhost:8500/v1/catalog/services

# 查询特定服务
curl http://localhost:8500/v1/catalog/service/user-service

# 查询健康的服务实例
curl http://localhost:8500/v1/health/service/user-service?passing=true

2.2 DNS 查询

# 查询服务
dig @127.0.0.1 -p 8600 user-service.service.consul

# 查询带 Tag 的服务
dig @127.0.0.1 -p 8600 primary.user-service.service.consul

# 查询 SRV 记录（包含端口）
dig @127.0.0.1 -p 8600 user-service.service.consul SRV

2.3 服务发现流程

三、Spring Cloud Consul

3.1 添加依赖

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-consul-discovery</artifactId>
</dependency>

3.2 配置文件

spring:
  application:
    name: user-service
  cloud:
    consul:
      host: localhost
      port: 8500
      discovery:
        service-name: ${spring.application.name}
        instance-id: ${spring.application.name}:${server.port}
        prefer-ip-address: true
        health-check-path: /actuator/health
        health-check-interval: 10s

3.3 启动类

@SpringBootApplication
@EnableDiscoveryClient
public class UserServiceApplication {
    public static void main(String[] args) {
        SpringApplication.run(UserServiceApplication.class, args);
    }
}

3.4 服务调用

@RestController
public class OrderController {
    
    @Autowired
    private DiscoveryClient discoveryClient;
    
    @Autowired
    @LoadBalanced
    private RestTemplate restTemplate;
    
    @GetMapping("/order/{id}")
    public Order getOrder(@PathVariable Long id) {
        // 使用服务名调用
        String url = "http://user-service/user/" + id;
        User user = restTemplate.getForObject(url, User.class);
        
        Order order = new Order();
        order.setId(id);
        order.setUser(user);
        return order;
    }
    
    @GetMapping("/instances")
    public List<ServiceInstance> getInstances() {
        return discoveryClient.getInstances("user-service");
    }
}

四、服务注销

4.1 HTTP API 注销

curl -X PUT http://localhost:8500/v1/agent/service/deregister/user-service-1

4.2 命令行注销

consul services deregister -id=user-service-1

4.3 Spring Cloud 自动注销

Spring Cloud Consul 在应用关闭时会自动注销服务。

五、服务元数据

5.1 配置元数据

spring:
  cloud:
    consul:
      discovery:
        metadata:
          version: v1.0.0
          region: beijing
          weight: 10

5.2 读取元数据

@GetMapping("/metadata")
public Map<String, String> getMetadata() {
    List<ServiceInstance> instances = discoveryClient.getInstances("user-service");
    if (!instances.isEmpty()) {
        return instances.get(0).getMetadata();
    }
    return Collections.emptyMap();
}

六、服务标签

6.1 配置标签

spring:
  cloud:
    consul:
      discovery:
        tags:
          - primary
          - v1
          - env=production

6.2 按标签查询

# DNS 查询
dig @127.0.0.1 -p 8600 primary.user-service.service.consul

# HTTP API
curl "http://localhost:8500/v1/catalog/service/user-service?tag=primary"

七、总结