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# keepalived高可用集群
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### keepalived介绍
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keepalived是集群管理中保证集群高可用的一个服务软件，其功能类似于heartbeat，用来防止单点故障。
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**脑裂**问题：
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backup vip
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master vip
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解决：**stonith** `shoot the other node in the head` **爆头**
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重启keepalived 关闭keepalived服务
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### keepalived工作原理
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keepalived是以**VRRP**协议为实现基础的，是实现路由器高可用的协议，VRRP全称Virtual Router Redundancy Protocol，即**虚拟路由冗余协议。**
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面试题(keepalived的工作原理)
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**将N台提供相同功能的服务器组成一个服务器组，这个组里面有一个master和多个backup，master上面有一个对外提供服务的vip（该服务器所在局域网内其他机器的默认路由为该vip），master会发组播，当backup收不到vrrp包时就认为master宕掉了，这时就需要根据VRRP的优先级来选举一个backup当master**
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keepalived主要有三个模块，分别是**core、check和vrrp**。core模块为keepalived的核心，负责主进程的启动、维护以及全局配置文件的加载和解析。check负责健康检查，包括常见的各种检查方式。vrrp模块是来实现VRRP协议的。
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### keepalived部署
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++++++++++++
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+---------------------------> + Client + 192.168.122.1/24 (真实机做客户端)
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| ++++++++++++
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| ________________|________________ VIP eth0:1 192.168.122.254/24
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| | |
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| ++++++++++++++++ +++++++++++++++++
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| + Director master + + Director backup +
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| ++++++++++++++++ +++++++++++++++++
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| DIP eth0 192.168.122.10/24 DIP eth0 192.168.122.20/24
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| |____________________________________________________________|
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|___________________________________________________________________ ____________________ _________|__________________________________________________
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| |
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| |
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++++++++++++++++ ++++++++++++++++
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\+ Real Server A + + Real Server B +
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++++++++++++++++ ++++++++++++++++
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eth0 192.168.122.30/24 eth0 192.168.122.40/24
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**分别在Director master、Director backup 上部署浮动资源（VIP IPVS策略）**
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**测试2个Director在DR模式下都工作正常。测试完成后都撤掉浮动资源。**
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**web上操作**
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web01 web02 添加同一网段虚拟网卡 且都是同一网段的
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**lvs上操作**
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在两台dr配置keepalivied (lvs上)
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**1. 在master上安装配置Keepalived**
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```bash
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# yum install keepalived -y
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```
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**2. 修改配置文件**(清空原有配置文件)
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```bash
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# cd /etc/keepalived/
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# vim keepalived.conf
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```
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//全局配置
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! Configuration File for keepalived
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global_defs {
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notification_email {
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root@localhost
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}
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notification_email_from keepalived@localhost
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smtp_server 127.0.0.1
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smtp_connect_timeout 30
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**router_id Director1** //两边是一样的
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}
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//局部配置
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vrrp_instance VI_1 {
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state **MASTER** //另外一台机器是BACKUP
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interface **eth0** //心跳网卡 DIP那一块网卡
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virtual_router_id 51
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priority **50** //优先级
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advert_int 1 //检查间隔，单位秒
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authentication {
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auth_type PASS
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auth_pass 1111
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}
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virtual_ipaddress {
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**192.168.122.254/24 dev eth0** //VIP随便自己定义(和web的是一个虚拟IP) 只要是同一个网段就可以
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}
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}
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virtual_server **192.168.122.254** 80 { //LVS 配置，VIP(和web的一个ip)上面是啥这块就是 ^
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delay_loop 3 //服务论询的时间间隔
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lb_algo rr //LVS 调度算法
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lb_kind DR // LVS 集群模式
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protocol TCP
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real_server **192.168.122.30** 80 {
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weight 1
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TCP_CHECK {
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connect_timeout 3
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}
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}
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real_server **192.168.122.40** 80 {
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weight 1
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TCP_CHECK {
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connect_timeout 3
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}
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}
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}
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**3.在backup上安装keepalived**
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```bash
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# yum install keepalived -y
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```
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**4.拷贝master上的keepalived.conf到backup上：**
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```bash
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# scp keepalived.conf 192.168.122.20:/etc/keepalived/
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```
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**5.拷贝后,修改配置文件**
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state **BACKUP**
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priority **100**
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**6.两个Director上启动服务**
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```bash
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# systemctl start keepalived
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```
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**7.测试**
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**7.测试**
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1）观察lvs路由条目
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2）观察vip地址在哪台机器上（有可能两台机器上都有，但是他好用没有问题即可）
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3）客户端浏览器访问vip
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4）关闭master上的keepalived服务，再次访问vip
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### 扩展实验-keepalived+mysql
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mysql可以是以下3种情况
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1、双主
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2、mysql-cluster
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3、gelara集群
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**项目环境**
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VIP 192.168.122.100
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mysql1 192.168.122.10
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mysql2 192.168.122.20
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vip
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主(keepalived) 主(keepalived）
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**实现过程概要**
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一、mysql 主主同步
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二、在两台mysql上安装keepalived
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三、keepalived 主备配置文件
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四、mysql状态检测脚本/root/bin/keepalived_check_mysql.sh
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五、测试及诊断
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注 keepalived之间使用vrrp组播方式通信使用的IP地址是224.0.0.18
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＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
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**实施步骤**
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**一、mysql 主主同步 <略>**
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**二、安装keepalived**
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```bash
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两台
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# yum install keepalived -y
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```
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**三、keepalived 主备配置文件**
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主备置文件不同处有 state priority
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------
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**192.168.122.10 Master配置**
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```bash
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# vim /etc/keepalived/keepalived.conf
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```
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! Configuration File for keepalived
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global_defs {
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router_id mysql1 //两边一样
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}
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**vrrp_script** **check_run** { //定义配置健康检查脚本的配置名称**check_run**
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script "/root/keepalived_check_mysql.sh"
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interval **5** //执行健康检查的时间间隔 单位s
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}
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vrrp_instance VI_1 {
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state MASTER
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interface eth0
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virtual_router_id 88
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priority 100
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advert_int 1 //检查keepalived本身服务的时间间隔
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authentication {
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auth_type PASS
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auth_pass 1111
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}
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track_script {
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**check_run** //名字必须和上面的脚本配置名称一致
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}
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virtual_ipaddress {
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**192.168.122.100** dev **eth0**
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}
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}
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------
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**192.168.122.20 Slave配置**
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```bash
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# vim /etc/keepalived/keepalived.conf
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```
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! Configuration File for keepalived
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global_defs {
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router_id mysql1
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}
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vrrp_script check_run {
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script "/root/keepalived_check_mysql.sh"
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interval 5
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}
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vrrp_instance VI_1 {
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state **BACKUP**
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interface eth0
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virtual_router_id 88
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priority **90**
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advert_int 1
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authentication {
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auth_type PASS
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auth_pass 1111
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}
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track_script {
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check_run
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}
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virtual_ipaddress {
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**192.168.122.100**
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}
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}
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**四、mysql状态检测脚本**
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/root/keepalived_check_mysql.sh（两台MySQL同样的脚本）
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版本一：简单使用：
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#!/bin/bash
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/usr/bin/mysql -h ip -uroot -p123 -e "show status;" &>/dev/null
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if [ $? -ne 0 ] ;then
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systemctl stop keepalived
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fi
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#此处的ip是本地ip
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版本二：检查多次
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vim /root/keepalived_check_mysql.sh
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#!/bin/bash
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MYSQL=/usr/local/mysql/bin/mysql
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MYSQL_HOST=localhost
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MYSQL_USER=root
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MYSQL_PASSWORD=1111
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CHECK_TIME=3
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#mysql is working MYSQL_OK is 1 , mysql down MYSQL_OK is 0
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MYSQL_OK=1
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check_mysql_helth (){
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$MYSQL -h $MYSQL_HOST -u $MYSQL_USER -p${MYSQL_PASSWORD} -e "show status;" &>/dev/null
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if [ $? -eq 0 ] ;then
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MYSQL_OK=1
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else
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MYSQL_OK=0
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fi
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return $MYSQL_OK
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}
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while [ $CHECK_TIME -ne 0 ]
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do
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check_mysql_helth
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if [ $MYSQL_OK -eq 1 ] ; then
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exit 0
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fi
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if [ $MYSQL_OK -eq 0 ] && [ $CHECK_TIME -eq 1 ];then
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/etc/init.d/keepalived stop
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exit 1
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fi
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let CHECK_TIME--
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sleep 1
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done
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版本三：检查多次
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vim /root/keepalived_check_mysql.sh
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#!/bin/bash
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MYSQL=/usr/local/mysql/bin/mysql
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MYSQL_HOST=localhost
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MYSQL_USER=root
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MYSQL_PASSWORD=1111
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CHECK_TIME=3
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#mysql is working MYSQL_OK is 1 , mysql down MYSQL_OK is 0
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MYSQL_OK=1
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check_mysql_helth (){
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$MYSQL -h $MYSQL_HOST -u $MYSQL_USER -p${MYSQL_PASSWORD} -e "show status;" &>/dev/null
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if [ $? -eq 0 ] ;then
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MYSQL_OK=1
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else
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MYSQL_OK=0
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fi
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return $MYSQL_OK
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}
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while [ $CHECK_TIME -ne 0 ]
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do
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check_mysql_helth
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if [ $MYSQL_OK -eq 1 ] ; then
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exit 0
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fi
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let CHECK_TIME--
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sleep 1
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done
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/etc/init.d/keepalived stop
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exit 1
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chmod 755 /root/keepalived_check_mysql.sh
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两边均启动keepalived
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日志查看脚本是否被执行
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tail -f /var/log/messages
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Jun 19 15:20:19 xen1 Keepalived_vrrp[6341]: Using LinkWatch kernel netlink reflector...
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Jun 19 15:20:19 xen1 Keepalived_vrrp[6341]: VRRP sockpool: [ifindex(2), proto(112), fd(11,12)]
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Jun 19 15:20:19 xen1 Keepalived_vrrp[6341]: VRRP_Script(check_run) succeeded
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