Consul快速入门（三）：Spring Cloud Consul实现服务注册与发现

1、前言

本文通过创建provider-service、consumer-service两个微服务，并通过feign接口调用来演示Spring Cloud整合Consul。阅读本文需要前置知识：

• Spring Boot
• Spring Cloud
• Spring Cloud Feign

2、搭建provider-service服务

2.1、创建maven模块

创建provider项目，添加provider-service、provider-service-remote-api两个maven模块：

2.2、添加spring boot、spring cloud依赖

在父模块provider中添加spring boot、spring cloud依赖
，spring cloud使用截止当前最新版本Hoxton.SR1，关联spring boot版本2.2.2.RELEASE

<properties>
    <java.version>1.8</java.version>
    <spring-cloud.version>Hoxton.SR1</spring-cloud.version>
</properties>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.2.2.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>${spring-cloud.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

注意：spring boot和spring cloud之间有版本依赖关系，如果想用其他版本，请自行查询对应的依赖版本，否则可能由于不兼容服务起不来

2.3、provider-service-remote-api模块编写feign接口

maven模块provider-service-remote-api引入spring cloud feign

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-openfeign</artifactId>
    </dependency>
</dependencies>

代码编写，新建IProviderRemoteService接口

@FeignClient(name = "provider-service")
public interface IProviderRemoteService {

    @RequestMapping(value = "hello", method = RequestMethod.GET)
    String hello();
}

2.4、provider-service模块编写接口实现

maven依赖

<dependency>
    <groupId>com.example</groupId>
    <artifactId>provider-service-remote-api</artifactId>
    <version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

接口实现类ProviderRemoteService

@RestController
public class ProviderRemoteService implements IProviderRemoteService {

    @Override
    public String hello() {
        return "hello world!";
    }
}

2.5、集成spring cloud consul

引入spring cloud consul模块

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

application.yml添加consul配置

server:
  port: 8080
spring:
  application:
    name: provider-service
  cloud:
    consul:
      host: 127.0.0.1
      port: 8500
      discovery:
        heartbeat:
          enabled: true

启动类添加@EnableDiscoveryClient注解，启用服务发现功能

@SpringBootApplication
@EnableDiscoveryClient
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

}

到此，provider-service服务已经全部搭建完毕，完整项目结构：

3、搭建consumer-service服务

3.1、创建maven模块

创建consumer项目，添加consumer-service，因为该服务不需要对外提供接口，所以无需consumer-service-remote-api模块：

3.2、consumer-service编写接口调用provider-service服务

引用provider-service-remote-api

<dependency>
    <groupId>com.example</groupId>
    <artifactId>provider-service-remote-api</artifactId>
    <version>0.0.1-SNAPSHOT</version>
</dependency>

编写测试接口，通过feign调用provider-service服务

@RestController
public class ConsumerController {

    @Autowired
    private IProviderRemoteService providerRemoteService;

    @RequestMapping(value = "/test")
    public String test() {
        return providerRemoteService.hello();
    }
}

3.3、集成spring cloud consul

同provider-service服务一样，引入spring cloud consul模块

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

application.yml添加consul配置

server:
  port: 9090
spring:
  application:
    name: consumer-service
  cloud:
    consul:
      host: 127.0.0.1
      port: 8500
      discovery:
        heartbeat:
          enabled: true

启动类添加@EnableDiscoveryClient注解，启用服务发现功能，并添加@EnableFeignClients注解，启用feign功能

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

}

到此，consumer-service服务也搭建完成，完整项目结构：

4、测试

4.1、启动consul服务

为了便于测试，笔者在本机以开发者模式起了一个consul服务

D:\consul>consul agent -dev
==> Starting Consul agent...
           Version: 'v1.7.0'
           Node ID: 'c43eedeb-f211-dbf2-e3fa-3caa64f86ddb'
         Node name: 'DESKTOP-77V3R9P'
        Datacenter: 'dc1' (Segment: '<all>')
            Server: true (Bootstrap: false)
       Client Addr: [127.0.0.1] (HTTP: 8500, HTTPS: -1, gRPC: 8502, DNS: 8600)
      Cluster Addr: 127.0.0.1 (LAN: 8301, WAN: 8302)
           Encrypt: Gossip: false, TLS-Outgoing: false, TLS-Incoming: false, Auto-Encrypt-TLS: false

==> Log data will now stream in as it occurs:

    2020-02-22T15:34:07.878+0800 [DEBUG] agent: Using random ID as node ID: id=c43eedeb-f211-dbf2-e3fa-3caa64f86ddb
    2020-02-22T15:34:07.900+0800 [DEBUG] agent.tlsutil: Update: version=1
    2020-02-22T15:34:07.914+0800 [DEBUG] agent.tlsutil: OutgoingRPCWrapper: version=1
    2020-02-22T15:34:07.916+0800 [INFO]  agent.server.raft: initial configuration: index=1 servers="[{Suffrage:Voter ID:c43eedeb-f211-dbf2-e3fa-3caa64f86ddb Address:127.0.0.1:8300}]"
    2020-02-22T15:34:07.916+0800 [INFO]  agent.server.raft: entering follower state: follower="Node at 127.0.0.1:8300 [Follower]" leader=
    2020-02-22T15:34:07.919+0800 [INFO]  agent.server.serf.wan: serf: EventMemberJoin: DESKTOP-77V3R9P.dc1 127.0.0.1
    2020-02-22T15:34:07.920+0800 [INFO]  agent.server.serf.lan: serf: EventMemberJoin: DESKTOP-77V3R9P 127.0.0.1
    2020-02-22T15:34:07.920+0800 [INFO]  agent.server: Adding LAN server: server="DESKTOP-77V3R9P (Addr: tcp/127.0.0.1:8300) (DC: dc1)"
    2020-02-22T15:34:07.921+0800 [INFO]  agent.server: Handled event for server in area: event=member-join server=DESKTOP-77V3R9P.dc1 area=wan
    2020-02-22T15:34:07.921+0800 [INFO]  agent: Started DNS server: address=127.0.0.1:8600 network=udp
    2020-02-22T15:34:07.923+0800 [INFO]  agent: Started DNS server: address=127.0.0.1:8600 network=tcp
    2020-02-22T15:34:07.926+0800 [INFO]  agent: Started HTTP server: address=127.0.0.1:8500 network=tcp
    2020-02-22T15:34:07.928+0800 [INFO]  agent: started state syncer
==> Consul agent running!
...

4.2、启动服务注册到consul

分别启动provider-service服务和consumer-service服务，访问consul的Web UI界面可以看到两个服务都注册上来了：

4.3、调用测试接口

调用consumer-service测试接口http://127.0.0.1:9090/test

现在尝试把provider服务停止，consul注册中心可以看到健康检查状态为Critical，服务已经下线

此时，再次调用consumer-service测试接口，会报找不到服务

5、Spring Cloud Consul应用配置

Name	Default	Description
spring.cloud.consul.config.acl-token
spring.cloud.consul.config.data-key	data	If format is Format.PROPERTIES or Format.YAML then the following field is used as key to look up consul for configuration.
spring.cloud.consul.config.default-context	application
spring.cloud.consul.config.enabled	TRUE
spring.cloud.consul.config.fail-fast	TRUE	Throw exceptions during config lookup if true, otherwise, log warnings.
spring.cloud.consul.config.format
spring.cloud.consul.config.name		Alternative to spring.application.name to use in looking up values in consul KV.
spring.cloud.consul.config.prefix	config
spring.cloud.consul.config.profile-separator	,
spring.cloud.consul.config.watch.delay	1000	The value of the fixed delay for the watch in millis. Defaults to 1000.
spring.cloud.consul.config.watch.enabled	TRUE	If the watch is enabled. Defaults to true.
spring.cloud.consul.config.watch.wait-time	55	The number of seconds to wait (or block) for watch query, defaults to 55. Needs to be less than default ConsulClient (defaults to 60). To increase ConsulClient timeout create a ConsulClient bean with a custom ConsulRawClient with a custom HttpClient.
spring.cloud.consul.discovery.acl-token
spring.cloud.consul.discovery.catalog-services-watch-delay	1000	The delay between calls to watch consul catalog in millis, default is 1000.
spring.cloud.consul.discovery.catalog-services-watch-timeout	2	The number of seconds to block while watching consul catalog, default is 2.
spring.cloud.consul.discovery.consistency-mode		Consistency mode for health service request.
spring.cloud.consul.discovery.datacenters		Map of serviceId’s → datacenter to query for in server list. This allows looking up services in another datacenters.
spring.cloud.consul.discovery.default-query-tag		Tag to query for in service list if one is not listed in serverListQueryTags.
spring.cloud.consul.discovery.default-zone-metadata-name	zone	Service instance zone comes from metadata. This allows changing the metadata tag name.
spring.cloud.consul.discovery.deregister	TRUE	Disable automatic de-registration of service in consul.
spring.cloud.consul.discovery.enabled	TRUE	Is service discovery enabled?
spring.cloud.consul.discovery.fail-fast	TRUE	Throw exceptions during service registration if true, otherwise, log warnings (defaults to true).
spring.cloud.consul.discovery.health-check-critical-timeout		Timeout to deregister services critical for longer than timeout (e.g. 30m). Requires consul version 7.x or higher.
spring.cloud.consul.discovery.health-check-headers		Headers to be applied to the Health Check calls.
spring.cloud.consul.discovery.health-check-interval	10s	How often to perform the health check (e.g. 10s), defaults to 10s.
spring.cloud.consul.discovery.health-check-path	/actuator/health	Alternate server path to invoke for health checking.
spring.cloud.consul.discovery.health-check-timeout		Timeout for health check (e.g. 10s).
spring.cloud.consul.discovery.health-check-tls-skip-verify		Skips certificate verification during service checks if true, otherwise runs certificate verification.
spring.cloud.consul.discovery.health-check-url		Custom health check url to override default.
spring.cloud.consul.discovery.heartbeat.enabled	FALSE
spring.cloud.consul.discovery.heartbeat.interval-ratio
spring.cloud.consul.discovery.heartbeat.ttl	30s
spring.cloud.consul.discovery.hostname		Hostname to use when accessing server.
spring.cloud.consul.discovery.include-hostname-in-instance-id	FALSE	Whether hostname is included into the default instance id when registering service.
spring.cloud.consul.discovery.instance-group		Service instance group.
spring.cloud.consul.discovery.instance-id		Unique service instance id.
spring.cloud.consul.discovery.instance-zone		Service instance zone.
spring.cloud.consul.discovery.ip-address		IP address to use when accessing service (must also set preferIpAddress to use).
spring.cloud.consul.discovery.lifecycle.enabled	TRUE
spring.cloud.consul.discovery.management-port		Port to register the management service under (defaults to management port).
spring.cloud.consul.discovery.management-suffix	management	Suffix to use when registering management service.
spring.cloud.consul.discovery.management-tags		Tags to use when registering management service.
spring.cloud.consul.discovery.order	0	Order of the discovery client used by?CompositeDiscoveryClient?for sorting available clients.
spring.cloud.consul.discovery.port		Port to register the service under (defaults to listening port).
spring.cloud.consul.discovery.prefer-agent-address	FALSE	Source of how we will determine the address to use.
spring.cloud.consul.discovery.prefer-ip-address	FALSE	Use ip address rather than hostname during registration.
spring.cloud.consul.discovery.query-passing	FALSE	Add the 'passing` parameter to /v1/health/service/serviceName. This pushes health check passing to the server.
spring.cloud.consul.discovery.register	TRUE	Register as a service in consul.
spring.cloud.consul.discovery.register-health-check	TRUE	Register health check in consul. Useful during development of a service.
spring.cloud.consul.discovery.scheme	http	Whether to register an http or https service.
spring.cloud.consul.discovery.server-list-query-tags		Map of serviceId’s → tag to query for in server list. This allows filtering services by a single tag.
spring.cloud.consul.discovery.service-name		Service name.
spring.cloud.consul.discovery.tags		Tags to use when registering service.
spring.cloud.consul.enabled	TRUE	Is spring cloud consul enabled.
spring.cloud.consul.host	localhost	Consul agent hostname. Defaults to ‘localhost’.
spring.cloud.consul.port	8500	Consul agent port. Defaults to ‘8500’.
spring.cloud.consul.retry.initial-interval	1000	Initial retry interval in milliseconds.
spring.cloud.consul.retry.max-attempts	6	Maximum number of attempts.
spring.cloud.consul.retry.max-interval	2000	Maximum interval for backoff.
spring.cloud.consul.retry.multiplier	1.1	Multiplier for next interval.
spring.cloud.consul.scheme		Consul agent scheme (HTTP/HTTPS). If there is no scheme in address - client will use HTTP.
spring.cloud.consul.tls.certificate-password		Password to open the certificate.
spring.cloud.consul.tls.certificate-path		File path to the certificate.
spring.cloud.consul.tls.key-store-instance-type		Type of key framework to use.
spring.cloud.consul.tls.key-store-password		Password to an external keystore.
spring.cloud.consul.tls.key-store-path		Path to an external keystore.

来源官网：https://cloud.spring.io/spring-cloud-consul/reference/html/appendix.html