分布式服务注册发现与统一配置管理之 Consul

猿友 2020-09-01 15:07:24 浏览数 (5192)
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文章转载自公众号：Java极客技术 作者：鸭血粉丝

今天这篇文章给大家介绍一个用于服务注册发现和管理配置的开源组件-- Consul 。接下来让我们一起来看一下它的功能吧。

背景

目前分布式系统架构已经基本普及，很多项目都是基于分布式架构的，以往的单机模式基本已经不适应当下互联网行业的发展。随着分布式项目的普及，项目服务实例数目的增加，服务的注册与发现功能就成了一项必不可少的架构。服务的注册与发现的功能，有很多开源方案。包括早期的zookeeper，百度的disconf，阿里的diamond，基于Go语言的ETCD，Spring集成的Eureka，以及前文提到的 Nacos 还有本文的主角Consul。这里不对上面提到的进行比较，本文仅介绍Consul，详细的对比，说明网上有很多资料，可以参考，例如：服务发现比较:Consul vs Zookeeper vs Etcd vs Eureka说到服务的注册与发现主要是下面两个主要功能：

  1. 服务注册与发现
  2. 配置中心即分布式项目统一配置管理

Consul 服务端配置使用

  1. 下载相应版本解压，并将可执行文件复制到/usr/local/consul目录下

  1. 创建一个service的配置文件 
    silence$ sudo mkdir /etc/consul.d
silence$ echo '{"service":{"name": "web", "tags": ["rails"], "port": 80}}' | sudo tee /etc/consul.d/web.json

  1. 启动代理

   silence$ /usr/local/consul/consul agent -dev -node consul_01 -config-dir=/etc/consul.d/ -ui

-dev 参数代表本地测试环境启动；-node 参数表示自定义集群名称；-config-drir 参数表示services的注册配置文件目录，即上面创建的文件夹-ui 启动自带的web-ui管理页面

  1. 集群成员查询方式

   silence-pro:~ silence$ /usr/local/consul/consul members

  1. HTTP协议数据查询

silence-pro:~ silence$ curl http://127.0.0.1:8500/v1/catalog/service/web
[
    {
        "ID": "ab1e3577-1b24-d254-f55e-9e8437956009",
        "Node": "consul_01",
        "Address": "127.0.0.1",
        "Datacenter": "dc1",
        "TaggedAddresses": {
            "lan": "127.0.0.1",
            "wan": "127.0.0.1"
        },
        "NodeMeta": {
            "consul-network-segment": ""
        },
        "ServiceID": "web",
        "ServiceName": "web",
        "ServiceTags": [
            "rails"
],
        "ServiceAddress": "",
        "ServicePort": 80,
        "ServiceEnableTagOverride": false,
        "CreateIndex": 6,
        "ModifyIndex": 6
    }
]
silence-pro:~ silence$

  1. web-ui管理 Consul Web UI

Consul Web UI

Consul的web-ui可以用来进行服务状态的查看，集群节点的检查，访问列表的控制以及KV存储系统的设置，相对于Eureka和ETCD，Consul的web-ui要好用的多。（Eureka和ETCD将在下一篇文章中简单介绍。）

7.KV存储的数据导入和导出

silence-pro:consul silence$ ./consul kv import @temp.json


silence-pro:consul silence$ ./consul kv export redis/

temp.json文件内容格式如下，一般是管理页面配置后先导出保存文件，以后需要再导入该文件

[
    {
        "key": "redis/config/password",
        "flags": 0,
        "value": "MTIzNDU2"
    },
    {
        "key": "redis/config/username",
        "flags": 0,
        "value": "U2lsZW5jZQ=="
    },
    {
        "key": "redis/zk/",
        "flags": 0,
        "value": ""
    },
    {
        "key": "redis/zk/password",
        "flags": 0,
        "value": "NDU0NjU="
    },
    {
        "key": "redis/zk/username",
        "flags": 0,
        "value": "ZGZhZHNm"
    }
]

Consul的KV存储系统是一种类似zk的树形节点结构，用来存储相关key/value键值对信息的，我们可以使用KV存储系统来实现上面提到的配置中心，将统一的配置信息保存在KV存储系统里面，方便各个实例获取并使用同一配置。而且更改配置后各个服务可以自动拉取最新配置，不需要重启服务。

Consul Java 客户端使用

  1. maven pom依赖增加，版本可自由更换

<dependency>
    <groupId>com.orbitz.consul</groupId>
    <artifactId>consul-client</artifactId>
    <version>0.12.3</version>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

  1. Consul 基本工具类，根据需要相应扩展

package com.coocaa.consul.consul.demo;


import com.google.common.base.Optional;
import com.google.common.net.HostAndPort;
import com.orbitz.consul.*;
import com.orbitz.consul.model.agent.ImmutableRegCheck;
import com.orbitz.consul.model.agent.ImmutableRegistration;
import com.orbitz.consul.model.health.ServiceHealth;


import java.net.MalformedURLException;
import java.net.URI;
import java.util.List;


public class ConsulUtil {


    private static Consul consul = Consul.builder().withHostAndPort(HostAndPort.fromString("127.0.0.1:8500")).build();


    /**


     * 服务注册


     */
    public static void serviceRegister() {
        AgentClient agent = consul.agentClient();


        try {
            /**


             * 注意该注册接口：
             * 需要提供一个健康检查的服务URL，以及每隔多长时间访问一下该服务（这里是3s）


             */
            agent.register(8080, URI.create("http://localhost:8080/health").toURL(), 3, "tomcat", "tomcatID", "dev");


        } catch (MalformedURLException e) {
            e.printStackTrace();
        }


    }


    /**


     * 服务获取


     *


     * @param serviceName


     */
    public static void findHealthyService(String serviceName) {
        HealthClient healthClient = consul.healthClient();
        List<ServiceHealth> serviceHealthList = healthClient.getHealthyServiceInstances(serviceName).getResponse();
        serviceHealthList.forEach((response) -> {
            System.out.println(response);
        });
    }


    /**


     * 存储KV


     */
    public static void storeKV(String key, String value) {
        KeyValueClient kvClient = consul.keyValueClient();
        kvClient.putValue(key, value);
    }


    /**


     * 根据key获取value


     */
    public static String getKV(String key) {
        KeyValueClient kvClient = consul.keyValueClient();
        Optional<String> value = kvClient.getValueAsString(key);
        if (value.isPresent()) {
            return value.get();
        }
        return "";
    }


    /**


     * 找出一致性的节点（应该是同一个DC中的所有server节点）


     */
    public static List<String> findRaftPeers() {
        StatusClient statusClient = consul.statusClient();
        return statusClient.getPeers();
    }


    /**


     * 获取leader


     */
    public static String findRaftLeader() {
        StatusClient statusClient = consul.statusClient();
        return statusClient.getLeader();
    }


    public static void main(String[] args) {
        AgentClient agentClient = consul.agentClient();
        agentClient.deregister("tomcatID");
    }
}

temp.json 和 ConsulUtil.java 文件以及上传到 GitHub 资源库，回复【源码仓库】获取代码地址。

3.通过上面的基本工具类可以实现服务的注册和KV数据的获取与存储功能

Consul集群搭建

  1. 三台主机Consul下载安装，我这里没有物理主机，所以通过三台虚拟机来实现。虚拟机IP分192.168.231.145，192.168.231.146，192.168.231.147

  1. 将145和146两台主机作为Server模式启动，147作为Client模式启动，Server和Client只是针对Consul集群来说的，跟服务没有任何关系！

  1. Server模式启动145，节点名称设为n1，数据中心统一用dc1

[root@centos145 consul]# ./consul agent -server -bootstrap-expect 2 -data-dir /tmp/consul -node=n1 -bind=192.168.231.145 -datacenter=dc1
bootstrap_expect = 2: A cluster with 2 servers will provide no failure tolerance. See https://www.consul.io/docs/internals/consensus.html#deployment-table
bootstrap_expect > 0: expecting 2 servers
==> Starting Consul agent...
==> Consul agent running!
           Version: 'v1.0.1'
           Node ID: '6cc74ff7-7026-cbaa-5451-61f02114cd25'
         Node name: 'n1'
        Datacenter: 'dc1' (Segment: '<all>')
            Server: true (Bootstrap: false)
       Client Addr: [127.0.0.1] (HTTP: 8500, HTTPS: -1, DNS: 8600)
      Cluster Addr: 192.168.231.145 (LAN: 8301, WAN: 8302)
           Encrypt: Gossip: false, TLS-Outgoing: false, TLS-Incoming: false


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


    2017/12/06 23:26:21 [INFO] raft: Initial configuration (index=0): []
    2017/12/06 23:26:21 [INFO] serf: EventMemberJoin: n1.dc1 192.168.231.145
    2017/12/06 23:26:21 [INFO] serf: EventMemberJoin: n1 192.168.231.145
    2017/12/06 23:26:21 [INFO] agent: Started DNS server 127.0.0.1:8600 (udp)
    2017/12/06 23:26:21 [INFO] raft: Node at 192.168.231.145:8300 [Follower] entering Follower state (Leader: "")
    2017/12/06 23:26:21 [INFO] consul: Adding LAN server n1 (Addr: tcp/192.168.231.145:8300) (DC: dc1)
    2017/12/06 23:26:21 [INFO] consul: Handled member-join event for server "n1.dc1" in area "wan"
    2017/12/06 23:26:21 [INFO] agent: Started DNS server 127.0.0.1:8600 (tcp)
    2017/12/06 23:26:21 [INFO] agent: Started HTTP server on 127.0.0.1:8500 (tcp)
    2017/12/06 23:26:21 [INFO] agent: started state syncer
    2017/12/06 23:26:28 [ERR] agent: failed to sync remote state: No cluster leader
    2017/12/06 23:26:30 [WARN] raft: no known peers, aborting election
    2017/12/06 23:26:49 [ERR] agent: Coordinate update error: No cluster leader
    2017/12/06 23:26:54 [ERR] agent: failed to sync remote state: No cluster leader
    2017/12/06 23:27:24 [ERR] agent: Coordinate update error: No cluster leader
    2017/12/06 23:27:27 [ERR] agent: failed to sync remote state: No cluster leader
    2017/12/06 23:27:56 [ERR] agent: Coordinate update error: No cluster leader
    2017/12/06 23:28:02 [ERR] agent: failed to sync remote state: No cluster leader
    2017/12/06 23:28:27 [ERR] agent: failed to sync remote state: No cluster leader
    2017/12/06 23:28:33 [ERR] agent: Coordinate update error: No cluster leader

目前只启动了145，所以还没有集群

4.Server模式启动146，节点名称用n2，并在n2上启用了web-ui管理页面功能

[root@centos146 consul]# ./consul agent -server -bootstrap-expect 2 -data-dir /tmp/consul -node=n2 -bind=192.168.231.146 -datacenter=dc1 -ui
bootstrap_expect = 2: A cluster with 2 servers will provide no failure tolerance. See https://www.consul.io/docs/internals/consensus.html#deployment-table
bootstrap_expect > 0: expecting 2 servers
==> Starting Consul agent...
==> Consul agent running!
           Version: 'v1.0.1'
           Node ID: 'eb083280-c403-668f-e193-60805c7c856a'
         Node name: 'n2'
        Datacenter: 'dc1' (Segment: '<all>')
            Server: true (Bootstrap: false)
       Client Addr: [127.0.0.1] (HTTP: 8500, HTTPS: -1, DNS: 8600)
      Cluster Addr: 192.168.231.146 (LAN: 8301, WAN: 8302)
           Encrypt: Gossip: false, TLS-Outgoing: false, TLS-Incoming: false


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


    2017/12/06 23:28:30 [INFO] raft: Initial configuration (index=0): []
    2017/12/06 23:28:30 [INFO] serf: EventMemberJoin: n2.dc1 192.168.231.146
    2017/12/06 23:28:31 [INFO] serf: EventMemberJoin: n2 192.168.231.146
    2017/12/06 23:28:31 [INFO] raft: Node at 192.168.231.146:8300 [Follower] entering Follower state (Leader: "")
    2017/12/06 23:28:31 [INFO] consul: Adding LAN server n2 (Addr: tcp/192.168.231.146:8300) (DC: dc1)
    2017/12/06 23:28:31 [INFO] consul: Handled member-join event for server "n2.dc1" in area "wan"
    2017/12/06 23:28:31 [INFO] agent: Started DNS server 127.0.0.1:8600 (tcp)
    2017/12/06 23:28:31 [INFO] agent: Started DNS server 127.0.0.1:8600 (udp)
    2017/12/06 23:28:31 [INFO] agent: Started HTTP server on 127.0.0.1:8500 (tcp)
    2017/12/06 23:28:31 [INFO] agent: started state syncer
    2017/12/06 23:28:38 [ERR] agent: failed to sync remote state: No cluster leader
    2017/12/06 23:28:39 [WARN] raft: no known peers, aborting election
    2017/12/06 23:28:57 [ERR] agent: Coordinate update error: No cluster leader
    2017/12/06 23:29:11 [ERR] agent: failed to sync remote state: No cluster leader
    2017/12/06 23:29:30 [ERR] agent: Coordinate update error: No cluster leader
    2017/12/06 23:29:38 [ERR] agent: failed to sync remote state: No cluster leader
    2017/12/06 23:29:57 [ERR] agent: Coordinate update error: No cluster leader

同样没有集群发现，此时n1和n2都启动起来，但是互相并不知道集群的存在！

5.将n1节点加入n2

   [silence@centos145 consul]$ ./consul join 192.168.231.146

此时n1和n2都打印发现了集群的日志信息

6.这个时候n1和n2两个节点已经是一个集群里面的Server模式的节点了

7.Client模式启动147

[root@centos147 consul]# ./consul agent -data-dir /tmp/consul -node=n3 -bind=192.168.231.147 -datacenter=dc1
==> Starting Consul agent...
==> Consul agent running!
           Version: 'v1.0.1'
           Node ID: 'be7132c3-643e-e5a2-9c34-cad99063a30e'
         Node name: 'n3'
        Datacenter: 'dc1' (Segment: '')
            Server: false (Bootstrap: false)
       Client Addr: [127.0.0.1] (HTTP: 8500, HTTPS: -1, DNS: 8600)
      Cluster Addr: 192.168.231.147 (LAN: 8301, WAN: 8302)
           Encrypt: Gossip: false, TLS-Outgoing: false, TLS-Incoming: false


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


    2017/12/06 23:36:46 [INFO] serf: EventMemberJoin: n3 192.168.231.147
    2017/12/06 23:36:46 [INFO] agent: Started DNS server 127.0.0.1:8600 (udp)
    2017/12/06 23:36:46 [INFO] agent: Started DNS server 127.0.0.1:8600 (tcp)
    2017/12/06 23:36:46 [INFO] agent: Started HTTP server on 127.0.0.1:8500 (tcp)
    2017/12/06 23:36:46 [INFO] agent: started state syncer
    2017/12/06 23:36:46 [WARN] manager: No servers available
    2017/12/06 23:36:46 [ERR] agent: failed to sync remote state: No known Consul servers
    2017/12/06 23:37:08 [WARN] manager: No servers available
    2017/12/06 23:37:08 [ERR] agent: failed to sync remote state: No known Consul servers
    2017/12/06 23:37:36 [WARN] manager: No servers available
    2017/12/06 23:37:36 [ERR] agent: failed to sync remote state: No known Consul servers
    2017/12/06 23:38:02 [WARN] manager: No servers available
    2017/12/06 23:38:02 [ERR] agent: failed to sync remote state: No known Consul servers
    2017/12/06 23:38:22 [WARN] manager: No servers available
    2017/12/06 23:38:22 [ERR] agent: failed to sync remote state: No known Consul servers

8.在n3上面将节点n3加入集群

   [silence@centos147 consul]$ ./consul join 192.168.231.145

9.再次查看集群节点信息

10.此时三个节点的Consul集群搭建成功了！其实n1和n2是Server模式启动，n3是Client模式启动。

11.关于Consul的Server模式和Client模式主要的区别是这样的，一个Consul集群通过启动的参数-bootstrap-expect来控制这个集群的Server节点个数，Server模式的节点会维护集群的状态，并且如果某个Server节点退出了集群，则会触发Leader重新选举机制，在会剩余的Server模式节点中重新选举一个Leader；而Client模式的节点的加入和退出很自由。

12.在n2中启动web-ui

分布式服务注册发现与统一配置管理之 Consul

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