# keepalived高可用集群

### keepalived介绍

    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。

**脑裂**问题：

backup vip

master vip

解决：**stonith** `shoot the other node in the head`	 **爆头**

重启keepalived 关闭keepalived服务

### keepalived工作原理

    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。**

面试题(keepalived的工作原理)
**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**

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。

### keepalived部署

														 ++++++++++++
	
	         +--------------------------->      +	   Client     +        192.168.122.1/24 (真实机做客户端)
	         |                                          ++++++++++++ 
	         |                                          ________________|________________      VIP eth0:1 192.168.122.254/24
	         |                                         |                            |
	         |                    ++++++++++++++++               +++++++++++++++++ 
	         |                   + Director master   +              +  Director backup  +
	         |                    ++++++++++++++++               +++++++++++++++++ 
	         |          DIP eth0 192.168.122.10/24         DIP eth0 192.168.122.20/24
	         |                                      |____________________________________________________________|
	         |___________________________________________________________________ ____________________ _________|__________________________________________________
	                                          |                                             | 
	                                          |                                             |
	
								++++++++++++++++              ++++++++++++++++
	
	                            \+   Real Server A    +              +  Real Server B      +
	
	                            ++++++++++++++++              ++++++++++++++++
	
	                            eth0 192.168.122.30/24       eth0 192.168.122.40/24

**分别在Director master、Director backup 上部署浮动资源（VIP IPVS策略）**
**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。**

**web上操作**

web01 web02 添加同一网段虚拟网卡 且都是同一网段的

**lvs上操作**

在两台dr配置keepalivied (lvs上)

**1. 在master上安装配置Keepalived**

```bash
# yum install keepalived -y
```

**2. 修改配置文件**(清空原有配置文件)

```bash
# cd /etc/keepalived/
# vim keepalived.conf
```

//全局配置
! Configuration File for keepalived
global_defs {						
	notification_email {
		root@localhost
		}
	notification_email_from keepalived@localhost
	smtp_server 127.0.0.1
	smtp_connect_timeout 30
	**router_id Director1**   //两边是一样的
	}
//局部配置	
vrrp_instance VI_1 {				
	state **MASTER**			  //另外一台机器是BACKUP	
	interface **eth0**			 //心跳网卡	  DIP那一块网卡
	virtual_router_id 51			
	priority **50**				    //优先级	
	advert_int 1				 //检查间隔，单位秒	
	authentication {
		auth_type PASS
		auth_pass 1111
		}
	virtual_ipaddress {
		**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
		}
	}
	
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 ^
	delay_loop 3                                  //服务论询的时间间隔
	lb_algo rr							           //LVS 调度算法
	lb_kind DR							           // LVS 集群模式
	protocol TCP
	real_server **192.168.122.30** 80 {
		weight 1
		TCP_CHECK {
			connect_timeout 3
			}
		}
	real_server **192.168.122.40** 80 {
		weight 1
		TCP_CHECK {
			connect_timeout 3
			}
		}
}

**3.在backup上安装keepalived**

```bash
# yum install keepalived -y
```

**4.拷贝master上的keepalived.conf到backup上：**

```bash
# scp keepalived.conf 192.168.122.20:/etc/keepalived/
```

**5.拷贝后,修改配置文件**
	state     **BACKUP**
	priority **100**
	
**6.两个Director上启动服务** 

```bash
# systemctl start keepalived
```

**7.测试**
**7.测试**
1）观察lvs路由条目
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）
3）客户端浏览器访问vip
4）关闭master上的keepalived服务，再次访问vip

### 扩展实验-keepalived+mysql 

   mysql可以是以下3种情况

1、双主

2、mysql-cluster

3、gelara集群

**项目环境**
VIP 192.168.122.100
mysql1 192.168.122.10
mysql2 192.168.122.20
                           vip
主(keepalived)             主(keepalived）

**实现过程概要**

一、mysql 主主同步
二、在两台mysql上安装keepalived
三、keepalived 主备配置文件
四、mysql状态检测脚本/root/bin/keepalived_check_mysql.sh
五、测试及诊断
注 keepalived之间使用vrrp组播方式通信使用的IP地址是224.0.0.18
＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
**实施步骤**
**一、mysql 主主同步 <略>**

**二、安装keepalived**

```bash
两台
# yum install keepalived -y
```

**三、keepalived 主备配置文件**
主备置文件不同处有 state  priority

------

**192.168.122.10 Master配置**

```bash
# vim /etc/keepalived/keepalived.conf
```

! Configuration File for keepalived

global_defs {
   router_id mysql1  //两边一样
}

**vrrp_script** **check_run** {   //定义配置健康检查脚本的配置名称**check_run**
   script "/root/keepalived_check_mysql.sh"
   interval **5**   //执行健康检查的时间间隔  单位s
}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 88
    priority 100
    advert_int 1          //检查keepalived本身服务的时间间隔
    authentication {
        auth_type PASS
        auth_pass 1111
    }

    track_script {
        **check_run**      //名字必须和上面的脚本配置名称一致
    }
    
    virtual_ipaddress {
        **192.168.122.100**  dev  **eth0**
    }
}

------

**192.168.122.20 Slave配置**

```bash
# vim /etc/keepalived/keepalived.conf
```

! Configuration File for keepalived

global_defs {
   router_id mysql1
}

vrrp_script check_run {
   script "/root/keepalived_check_mysql.sh"
   interval 5
}

vrrp_instance VI_1 {
    state **BACKUP**
    interface eth0
    virtual_router_id 88
    priority **90**
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }

    track_script {
        check_run
    }
    
    virtual_ipaddress {
        **192.168.122.100**
    }
}

**四、mysql状态检测脚本**

/root/keepalived_check_mysql.sh（两台MySQL同样的脚本）

版本一：简单使用：
#!/bin/bash
/usr/bin/mysql -h ip -uroot -p123 -e "show status;" &>/dev/null
if [ $? -ne 0 ] ;then
        systemctl stop keepalived
fi

#此处的ip是本地ip

版本二：检查多次

vim  /root/keepalived_check_mysql.sh

#!/bin/bash
MYSQL=/usr/local/mysql/bin/mysql
MYSQL_HOST=localhost
MYSQL_USER=root
MYSQL_PASSWORD=1111
CHECK_TIME=3

#mysql  is working MYSQL_OK is 1 , mysql down MYSQL_OK is 0
MYSQL_OK=1

check_mysql_helth (){
    $MYSQL -h $MYSQL_HOST -u $MYSQL_USER -p${MYSQL_PASSWORD} -e "show status;" &>/dev/null
    if [ $? -eq 0 ] ;then
        MYSQL_OK=1
    else
        MYSQL_OK=0
    fi
    return $MYSQL_OK
}

while [ $CHECK_TIME -ne 0 ]
do
        check_mysql_helth
        if [ $MYSQL_OK -eq 1 ] ; then
                exit 0
        fi

        if [ $MYSQL_OK -eq 0 ] &&  [ $CHECK_TIME -eq 1 ];then
                /etc/init.d/keepalived stop
                exit 1
        fi
        let CHECK_TIME--
        sleep 1
done

版本三：检查多次

vim  /root/keepalived_check_mysql.sh

#!/bin/bash
MYSQL=/usr/local/mysql/bin/mysql
MYSQL_HOST=localhost
MYSQL_USER=root
MYSQL_PASSWORD=1111
CHECK_TIME=3

#mysql  is working MYSQL_OK is 1 , mysql down MYSQL_OK is 0
MYSQL_OK=1

check_mysql_helth (){
    $MYSQL -h $MYSQL_HOST -u $MYSQL_USER -p${MYSQL_PASSWORD} -e "show status;" &>/dev/null
    if [ $? -eq 0 ] ;then
        MYSQL_OK=1
    else
        MYSQL_OK=0
    fi
    return $MYSQL_OK
}

while [ $CHECK_TIME -ne 0 ]
do
        check_mysql_helth
        if [ $MYSQL_OK -eq 1 ] ; then
                exit 0
        fi

        let CHECK_TIME--
        sleep 1
done
/etc/init.d/keepalived stop
exit 1

chmod 755 /root/keepalived_check_mysql.sh

两边均启动keepalived

日志查看脚本是否被执行

tail -f /var/log/messages

Jun 19 15:20:19 xen1 Keepalived_vrrp[6341]: Using LinkWatch kernel netlink reflector...
Jun 19 15:20:19 xen1 Keepalived_vrrp[6341]: VRRP sockpool: [ifindex(2), proto(112), fd(11,12)]
Jun 19 15:20:19 xen1 Keepalived_vrrp[6341]: VRRP_Script(check_run) succeeded