Consul 简介及集群安装

简介

Consul是基于GO语言开发的开源工具，主要面向分布式，服务化的系统提供服务注册、服务发现和配置管理的功能。
Consul的功能都很实用，其中包括：服务注册/发现、健康检查、Key/Value存储、多数据中心和分布式一致性保证等特性。
Consul本身只是一个二进制的可执行文件，所以安装和部署都非常简单，只需要从官网下载后，在执行对应的启动脚本即可。
官网下载地址: https://www.consul.io/downloads.html

特性

基础特性
1. 服务注册/发现
2. 数据强一致型保证
3. 多数据中心
4. 健康检查
5. Key/Value存储
高级特性
- HTTP API
- ACL

工作模式

Consul中包括的3种不同的角色：Client、Server、Server-Leader。
还有一个在图上没有标出来的角色Agent，一共4个角色。
Agent
- 是一个守护线程
- 跟随Consul应用启动而启动
- 负责检查、维护节点同步
Client
- 转发所有请求给Server
- 无状态, 不持久化数据
- 参与LAN Gossip的健康检查
Server
- 持久化数据
- 转发请求给Server-Leader
- 参与Server-Leader选举
- 通过WAN Gossip(流言算法协议, Cassandra和比特币的底层算法, 符合弱一致性), 与其他数据中心交换数据
Server-Leader
- 响应RPC请求
- 将服务列表数据同步给Server

工作原理

服务注册的方式

HTTP API

http://{ip}:8500/v1/agent/service/register/:service

JSON 配置文件

{
    "services": [
            {
                    "id": "serverId",
                    "name": "serverName",
                    "tags": [
                            "primary"
                    ],
                    "address": "127.0.0.1",
                    "port": 9003,
                    "checks": [
                            {
                                    "id": "api-servie",
                                    "name": "Service 'xx' check",
                                    "http": "http://127.0.0.1:9003/public/health",
                                    "method": "GET",
                                    "interval": "10s",
                                    "timeout": "1s"
                            }
                    ]
            }
    ]

启动增加参数: -config-dir

nohup ./consul agent -dev -config-dir=/consul-conf/service.json &

服务发现的方式
1. HTTP API
  - 获取某个service下健康的服务列表信息
```
http://{ip}:8500/v1/health/service/:service
```
2. DNS Agent
工作流程

集群搭建

这次我们以二进制包方式搭建, 其实还有docker的方式。
我使用的系统为ubuntu18.04LTS
集群规划:node01, node02, node03, node04, node05上都安装
集群前置准备请参考: https://www.cnblogs.com/ronnieyuan/p/11461377.html

上传二进制包并解压到指定目录

unzip consul_1.6.2_linux_amd64.zip -d /usr/bin

解压后直接就是一个可执行文件了

vim ~/.bashrc 修改环境变量

# Consul
export CONSUL_HOME=/usr/bin/consul
export PATH=$PATH:CONSUL_HOME

验证Consul安装是否成功

root@node01:/home/ronnie/soft# consul version
Consul v1.6.2
Protocol 2 spoken by default, understands 2 to 3 (agent will automatically use protocol >2 when speaking to compatible agents)
root@node01:/home/ronnie/soft# vim ~/.bashrc

将二进制文件拷贝至其他几台虚拟机上, 记得修改配置文件

cd /usr/bin/
scp consul root@node02:`pwd`
scp consul root@node03:`pwd`
scp consul root@node04:`pwd`
scp consul root@node05:`pwd`

分别在五台虚拟机上输入以下对应的命令

# node01
consul agent -server -ui -bootstrap-expect=5 -data-dir=/data/consul -node=agent-1 -client=0.0.0.0 -bind=192.168.180.130 -datacenter=dc1

# node02
consul agent -server -ui -bootstrap-expect=5 -data-dir=/data/consul -node=agent-2 -client=0.0.0.0 -bind=192.168.180.131 -datacenter=dc1 -join 192.168.180.130

# node03
consul agent -server -ui -bootstrap-expect=5 -data-dir=/data/consul -node=agent-3 -client=0.0.0.0 -bind=192.168.180.132 -datacenter=dc1 -join 192.168.180.130

# node04
consul agent -server -ui -bootstrap-expect=5 -data-dir=/data/consul -node=agent-4 -client=0.0.0.0 -bind=192.168.180.133 -datacenter=dc1 -join 192.168.180.130

# node05
consul agent -server -ui -bootstrap-expect=5 -data-dir=/data/consul -node=agent-5 -client=0.0.0.0 -bind=192.168.180.134 -datacenter=dc1 -join 192.168.180.130

命令解读:
- -bootstrap-expect=5: 指定了集群有5台
- -node=agent-x: 指定服务器
- -client=0.0.0.0: 指定当前主机客户端侦听地址为0.0.0.0
- -bind: 绑定当前主机的ip地址
- -datacenter=dc: 指定了一个数据中心的名称
- -join 192.168.180.130: 后几台服务器在启动的时候加入第一台代理服务器node01(PS，比较坑的是即使已经改过hostname文件, 还是得敲ip)
- -ui指定了启用每台服务器的内置 WebUI 服务器组件
- 当五台服务器都正确运行起来以后，Consul 集群将自动选举 leader，自动进行集群事务，无需干预。

启动成功案例

==> bind_addr cannot be empty
root@node02:~# consul agent -server -ui -bootstrap-expect=5 -data-dir=/data/consul -node=agent-2 -client=0.0.0.0 -bind=192.168.180.131 -datacenter=dc1 -join 192.168.180.130
bootstrap_expect > 0: expecting 5 servers
==> Starting Consul agent...
           Version: 'v1.6.2'
           Node ID: '304a1a5a-2987-e7ad-738d-7d21f9dbd887'
         Node name: 'agent-2'
        Datacenter: 'dc1' (Segment: '<all>')
            Server: true (Bootstrap: false)
       Client Addr: [0.0.0.0] (HTTP: 8500, HTTPS: -1, gRPC: -1, DNS: 8600)
      Cluster Addr: 192.168.180.131 (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:

    2019/11/29 22:19:15 [INFO]  raft: Initial configuration (index=0): []
    2019/11/29 22:19:15 [INFO]  raft: Node at 192.168.180.131:8300 [Follower] entering Follower state (Leader: "")
    2019/11/29 22:19:15 [INFO] serf: EventMemberJoin: agent-2.dc1 192.168.180.131
    2019/11/29 22:19:15 [INFO] serf: EventMemberJoin: agent-2 192.168.180.131
    2019/11/29 22:19:15 [INFO] consul: Adding LAN server agent-2 (Addr: tcp/192.168.180.131:8300) (DC: dc1)
    2019/11/29 22:19:15 [INFO] agent: Started DNS server 0.0.0.0:8600 (udp)
    2019/11/29 22:19:15 [INFO] consul: Handled member-join event for server "agent-2.dc1" in area "wan"
    2019/11/29 22:19:15 [INFO] agent: Started DNS server 0.0.0.0:8600 (tcp)
    2019/11/29 22:19:15 [INFO] agent: Started HTTP server on [::]:8500 (tcp)
==> Joining cluster...
    2019/11/29 22:19:15 [INFO] agent: (LAN) joining: [192.168.180.130]
    2019/11/29 22:19:15 [INFO] serf: EventMemberJoin: agent-1 192.168.180.130
    2019/11/29 22:19:15 [INFO] agent: (LAN) joined: 1
    Join completed. Synced with 1 initial agents
    2019/11/29 22:19:15 [INFO] agent: started state syncer
==> Consul agent running!
    2019/11/29 22:19:15 [INFO] consul: Adding LAN server agent-1 (Addr: tcp/192.168.180.130:8300) (DC: dc1)
    2019/11/29 22:19:15 [INFO] serf: EventMemberJoin: agent-1.dc1 192.168.180.130
    2019/11/29 22:19:15 [INFO] consul: Handled member-join event for server "agent-1.dc1" in area "wan"
    2019/11/29 22:19:17 [INFO] serf: EventMemberJoin: agent-3.dc1 192.168.180.132
    2019/11/29 22:19:17 [INFO] consul: Handled member-join event for server "agent-3.dc1" in area "wan"
    2019/11/29 22:19:17 [INFO] serf: EventMemberJoin: agent-3 192.168.180.132
    2019/11/29 22:19:17 [INFO] consul: Adding LAN server agent-3 (Addr: tcp/192.168.180.132:8300) (DC: dc1)
    2019/11/29 22:19:17 [INFO] serf: EventMemberJoin: agent-4.dc1 192.168.180.133
    2019/11/29 22:19:17 [INFO] consul: Handled member-join event for server "agent-4.dc1" in area "wan"
    2019/11/29 22:19:18 [INFO] serf: EventMemberJoin: agent-4 192.168.180.133
    2019/11/29 22:19:18 [INFO] consul: Adding LAN server agent-4 (Addr: tcp/192.168.180.133:8300) (DC: dc1)
    2019/11/29 22:19:18 [INFO] serf: EventMemberJoin: agent-5 192.168.180.134
    2019/11/29 22:19:18 [INFO] consul: Adding LAN server agent-5 (Addr: tcp/192.168.180.134:8300) (DC: dc1)
    2019/11/29 22:19:18 [INFO] consul: Existing Raft peers reported by agent-5, disabling bootstrap mode
    2019/11/29 22:19:18 [INFO] serf: EventMemberJoin: agent-5.dc1 192.168.180.134
    2019/11/29 22:19:18 [INFO] consul: Handled member-join event for server "agent-5.dc1" in area "wan"
    2019/11/29 22:19:19 [WARN]  raft: Failed to get previous log: 1 log not found (last: 0)
    2019/11/29 22:19:19 [INFO] agent: Synced node info
    2019/11/29 22:19:19 [INFO] consul: New leader elected: agent-1
==> Failed to check for updates: Get https://checkpoint-api.hashicorp.com/v1/check/consul?arch=amd64&os=linux&signature=6977bf57-e750-2607-d65d-fa3ab1444055&version=1.6.2: net/http: request canceled (Client.Timeout exceeded while awaiting headers)

在浏览器上访问node01节点的8500端口
那么本次集群的安装就到此为止了

Consul 简介及集群安装

简介

特性

工作模式

工作原理

集群搭建

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