Spring Cloud Spring Boot mybatis 企业分布式微服务云（二）服务注册与发现（Consul）

Spring Cloud Consul

Spring Cloud Consul项目是针对Consul的服务治理实现。Consul是一个分布式高可用的系统，它包含多个组件，可是做为一个总体，在微服务架构中为咱们的基础设施提供服务发现和服务配置的工具。它包含了下面几个特性：

• 服务发现
• 健康检查
• Key/Value存储
• 多数据中心

因为Spring Cloud Consul项目的实现，咱们能够轻松的将基于Spring Boot的微服务应用注册到Consul上，并经过此实现微服务架构中的服务治理。

以以前实现的基于Eureka的示例（eureka-client）为基础，咱们如何将以前实现的服务提供者注册到Consul上呢？方法很是简单，咱们只须要在pom.xml中将eureka的依赖修改成以下依赖：

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

接下来再修改一下application.properites，将consul须要的配置信息加入便可，好比：（下面配置是默认值）

spring.cloud.consul.host=localhost spring.cloud.consul.port=8500

到此为止，咱们将eureka-client转换为基于consul服务治理的服务提供者就完成了。前文咱们已经有提到过服务发现的接口DiscoveryClient是Spring Cloud对服务治理作的一层抽象，因此能够屏蔽Eureka和Consul服务治理的实现细节，咱们的程序不须要作任何改变，只须要引入不一样的服务治理依赖，并配置相关的配置属性就能轻松的将微服务归入Spring Cloud的各个服务治理框架中。

下面能够尝试让consul的服务提供者运行起来。这里可能读者会问，不须要建立相似eureka-server的服务端吗？因为Consul自身提供了服务端，因此咱们不须要像以前实现Eureka的时候建立服务注册中心，直接经过下载consul的服务端程序就可使用。

咱们能够用下面的命令启动consul的开发模式：

$consul agent -dev
==> Starting Consul agent...
==> Starting Consul agent RPC...
==> Consul agent running!
           Version: 'v0.7.2'
         Node name: 'Lenovo-zhaiyc'
        Datacenter: 'dc1'
            Server: true (bootstrap: false)
       Client Addr: 127.0.0.1 (HTTP: 8500, HTTPS: -1, DNS: 8600, RPC: 8400)
      Cluster Addr: 127.0.0.1 (LAN: 8301, WAN: 8302)
    Gossip encrypt: false, RPC-TLS: false, TLS-Incoming: false
             Atlas: <disabled>

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

    2017/06/22 07:50:54 [INFO] raft: Initial configuration (index=1): [{Suffrage:Voter ID:127.0.0.1:8300 Address:127.0.0.1:8300}]
    2017/06/22 07:50:54 [INFO] raft: Node at 127.0.0.1:8300 [Follower] entering Follower state (Leader: "")
    2017/06/22 07:50:54 [INFO] serf: EventMemberJoin: Lenovo-zhaiyc 127.0.0.1
    2017/06/22 07:50:54 [INFO] consul: Adding LAN server Lenovo-zhaiyc (Addr: tcp/127.0.0.1:8300) (DC: dc1)
    2017/06/22 07:50:54 [INFO] serf: EventMemberJoin: Lenovo-zhaiyc.dc1 127.0.0.1
    2017/06/22 07:50:54 [INFO] consul: Adding WAN server Lenovo-zhaiyc.dc1 (Addr: tcp/127.0.0.1:8300) (DC: dc1)
    2017/06/22 07:51:01 [ERR] agent: failed to sync remote state: No cluster leader
    2017/06/22 07:51:02 [WARN] raft: Heartbeat timeout from "" reached, starting election
    2017/06/22 07:51:02 [INFO] raft: Node at 127.0.0.1:8300 [Candidate] entering Candidate state in term 2
    2017/06/22 07:51:02 [DEBUG] raft: Votes needed: 1
    2017/06/22 07:51:02 [DEBUG] raft: Vote granted from 127.0.0.1:8300 in term 2. Tally: 1
    2017/06/22 07:51:02 [INFO] raft: Election won. Tally: 1
    2017/06/22 07:51:02 [INFO] raft: Node at 127.0.0.1:8300 [Leader] entering Leader state
    2017/06/22 07:51:02 [INFO] consul: cluster leadership acquired
    2017/06/22 07:51:02 [INFO] consul: New leader elected: Lenovo-zhaiyc
    2017/06/22 07:51:02 [DEBUG] consul: reset tombstone GC to index 3
    2017/06/22 07:51:02 [INFO] consul: member 'Lenovo-zhaiyc' joined, marking health alive
    2017/06/22 07:51:02 [INFO] agent: Synced service 'consul'
    2017/06/22 07:51:02 [DEBUG] agent: Node info in sync

consul服务端启动完成以后，咱们再将以前改造后的consul服务提供者启动起来。consul与eureka同样，都提供了简单的ui界面来查看服务的注册状况：

源码来源