debian6下redis+keepalived故障自动切换

5544992

环境介绍：

Master: 1192.168.2.140

Slave:
1192.168.2.141

Virtural IP Address (VIP): 192.168.200.16

设计思路：

当 Master 与 Slave 均运作正常时, Master负责服务，Slave负责Standby；

当 Master 挂掉，Slave 正常时, Slave接管服务，同时关闭主从复制功能；

当 Master 恢复正常，则从Slave同步数据，同步数据之后关闭主从复制功能，恢复Master身份，于此同时Slave等待Master同步数据完成之后，恢复Slave身份。

然后依次循环。

需要注意的是，这样做需要在Master与Slave上都开启本地化策略，否则在互相自动切换的过程中，未开启本地化的一方会将另一方的数据清空，造成数据完全丢失。

1.安装keepalived



root@dead:/usr/local/src# wget http://www.keepalived.org/software/keepalived-1.2.13.tar.gzroot@dead:/usr/local/src# tar -xzvf keepalived-1.2.13.tar.gz
root@dead:/usr/local/src# mv keepalived-1.2.13 /usr/local/
root@dead:/usr/local/keepalived-1.2.13# ./configure
注意：执行完configure操作后，可能会出现如下错误：　　



configure: error:
!!! OpenSSL is not properly installed on your system. !!!
!!! Can not include OpenSSL headers files.            !!!
若出现，执行如下操作：　　



root@dead:/usr/local/keepalived-1.2.13# apt-get install libssl-dev
安装结束后，再次执行configure操作，正常执行！　　









root@dead:/usr/local/keepalived-1.2.13# make && make install
　　

在Master和Slave上安装Keepalived结束！

2.编辑Master和Slave的keepalived.conf文件



root@dead:/usr/local/etc/keepalived# vi keepalived.confmaster编辑如下，若不存在则增加，存在则修改，多余不用碰：vrrp_script chk_redis {
script "/etc/keepalived/scripts/redis_check.sh"   ###监控脚本
interval 2                                        ###监控时间
}
vrrp_instance VI_1 {
state MASTER                            ###设置为MASTER
interface eth0                          ###监控网卡   
virtual_router_id 51
priority 101                            ###权重值
authentication {
auth_type PASS             ###加密
auth_pass 1111            ###密码
}
track_script {
chk_redis                       ###执行上面定义的chk_redis
}
virtual_ipaddress {
192.168.200.16                         ###VIP
}
notify_master /etc/keepalived/scripts/redis_master.sh
notify_backup /etc/keepalived/scripts/redis_backup.sh
notify_fault  /etc/keepalived/scripts/redis_fault.sh
notify_stop   /etc/keepalived/scripts/redis_stop.sh
}


slave编辑如下，若不存在则增加，存在则修改，多余不用碰： vrrp_script chk_redis {
script "/etc/keepalived/scripts/redis_check.sh"   ###监控脚本
interval 2                                        ###监控时间
}
vrrp_instance VI_1 {
state BACKUP                                ###设置为BACKUP
interface eth0                              ###监控网卡
virtual_router_id 51
priority 100                                ###比MASTRE权重值低
authentication {
auth_type PASS
auth_pass redis                ###密码与MASTRE相同
}
track_script {
chk_redis                       ###执行上面定义的chk_redis

}
virtual_ipaddress {
192.168.200.16                        ###VIP
}
notify_master /etc/keepalived/scripts/redis_master.sh
notify_backup /etc/keepalived/scripts/redis_backup.sh
notify_fault  /etc/keepalived/scripts/redis_fault.sh
notify_stop   /etc/keepalived/scripts/redis_stop.sh
}
　　





在Master和Slave上创建监控Redis的脚本



root@dead:/etc# mkdir /etc/keepalived
root@dead:/etc# mkdir /etc/keepalived/scriptsroot@dead:/etc# vi /etc/keepalived/scripts/redis_check.sh
增加如下：　　



#!/bin/bash
ALIVE=`/usr/local/redis-2.8.13/src/redis-cli -p 12002 PING`
if [ "$ALIVE" == "PONG" ]; then
echo $ALIVE
exit 0
else
echo $ALIVE
exit 1
fi
　　

编写以下负责运作的关键脚本：

notify_master /etc/keepalived/scripts/redis_master.sh

notify_backup /etc/keepalived/scripts/redis_backup.sh

notify_fault /etc/keepalived/scripts/redis_fault.sh

notify_stop /etc/keepalived/scripts/redis_stop.sh

因为Keepalived在转换状态时会依照状态来呼叫：

当进入Master状态时会呼叫notify_master

当进入Backup状态时会呼叫notify_backup

当发现异常情况时进入Fault状态呼叫notify_fault

当Keepalived程序终止时则呼叫notify_stop

首先，在Redis Master上创建notity_master与notify_backup脚本：

root@dead:/etc# vi  /etc/keepalived/scripts/redis_master.sh
#!/bin/bash
REDISCLI="/usr/local/redis-2.8.13/src/redis-cli -p 12002"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "[master]" >> $LOGFILE
date >> $LOGFILE
echo "Being master...." >> $LOGFILE 2>&1
echo "Run SLAVEOF cmd ..." >> $LOGFILE
$REDISCLI SLAVEOF 192.168.2.141 12002 >> $LOGFILE  2>&1
sleep 10 #延迟10秒以后待数据同步完成后再取消同步状态
echo "Run SLAVEOF NO ONE cmd ..." >> $LOGFILE
$REDISCLI SLAVEOF NO ONE >> $LOGFILE 2>&1</pre><pre name=&quot;code&quot; class=&quot;html&quot;>vi /etc/keepalived/scripts/redis_backup.sh#!/bin/bash
REDISCLI=&quot;/usr/local/redis-2.8.13/src/redis-cli -p 12002&quot;
LOGFILE=&quot;/var/log/keepalived-redis-state.log&quot;
echo &quot;[backup]&quot; >> $LOGFILE
date >> $LOGFILE
echo &quot;Being slave....&quot; >> $LOGFILE 2>&1
sleep 15 #延迟15秒待数据被对方同步完成之后再切换主从角色
echo &quot;Run SLAVEOF cmd ...&quot; >> $LOGFILE
$REDISCLI SLAVEOF 192.168.2.141 12002 >> $LOGFILE  2>&1

接着，在Redis Slave上创建notity_master与notify_backup脚本：



vi  /etc/keepalived/scripts/redis_master.sh#!/bin/bash
REDISCLI=&quot;/usr/local/redis-2.8.13/src/redis-cli -p 12002&quot;
LOGFILE=&quot;/var/log/keepalived-redis-state.log&quot;
echo &quot;[master]&quot; >> $LOGFILE
date >> $LOGFILE
echo &quot;Being master....&quot; >> $LOGFILE 2>&1
echo &quot;Run SLAVEOF cmd ...&quot; >> $LOGFILE
$REDISCLI SLAVEOF 192.168.2.140 12002 >> $LOGFILE  2>&1
sleep 10 #延迟10秒以后待数据同步完成后再取消同步状态
echo &quot;Run SLAVEOF NO ONE cmd ...&quot; >> $LOGFILE
$REDISCLI SLAVEOF NO ONE >> $LOGFILE 2>&1vi /etc/keepalived/scripts/redis_backup.sh　　



#!/bin/bash
REDISCLI=&quot;/usr/local/redis-2.8.13/src/redis-cli -p 12002&quot;
LOGFILE=&quot;/var/log/keepalived-redis-state.log&quot;
echo &quot;[backup]&quot; >> $LOGFILE
date >> $LOGFILE
echo &quot;Being slave....&quot; >> $LOGFILE 2>&1
sleep 15 #延迟15秒待数据被对方同步完成之后再切换主从角色
echo &quot;Run SLAVEOF cmd ...&quot; >> $LOGFILE
$REDISCLI SLAVEOF 192.168.2.140 12002 >> $LOGFILE  2>&1

然后在Master与Slave创建如下相同的脚本：　　



/etc/keepalived/scripts/redis_fault.sh

#!/bin/bash
LOGFILE=/var/log/keepalived-redis-state.log
echo &quot;[fault]&quot; >> $LOGFILE
date >> $LOGFILE

vi /etc/keepalived/scripts/redis_stop.sh

#!/bin/bash
LOGFILE=/var/log/keepalived-redis-state.log
echo &quot;[stop]&quot; >> $LOGFILE
date >> $LOGFILE


给脚本都加上可执行权限：

$ sudo chmod &#43;x /etc/keepalived/scripts/*.sh　　



脚本创建完成以后，我们开始按照如下流程进行测试：

1.启动Master上的Redis

$  /usr/local/redis-2.8.13/src/redis-server  /usr/local/redis-2.8.13/redis.conf

2.启动Slave上的Redis

$  /usr/local/redis-2.8.13/src/redis-server  /usr/local/redis-2.8.13/redis.conf

3.启动Master上的Keepalived

$ root@dead:/usr/local/etc/keepalived# keepalived

4.启动Slave上的Keepalived

$
usr/local/etc/keepalived# keepalived

5.尝试通过VIP连接Redis:

$ /usr/local/redis-2.8.13/src/redis-cli -h 192.168.200.16 -p 12002 INFO

注意：在master上执行此操作时会报如下错误：



Could not connect to Redis at 192.168.200.16:12002: No route to host
采取措施1：（在master和slave中修改文件如下）　　



vi /etc/hosts127.0.0.1   localhost
192.168.2.140  redis
192.168.2.141  redis-slave
执行依然出错！　　

采取措施2：



cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/执行操作成功！
　　

连接成功，Slave也连接上来了。连接后，显示的部分内容如下：



# Replication
role:master
connected_slaves:1
slave0:ip=192.168.2.141,port=12002,state=online,offset=520,lag=0
master_repl_offset:520
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:17
repl_backlog_histlen:504

　　

6.尝试插入一些数据：



root@dead:/usr/local/etc/keepalived# /usr/local/redis-2.8.13/src/redis-cli -h 192.168.200.16 -p 12002
192.168.200.16:12002> set go gotodeath
OK
192.168.200.16:12002> get go
&quot;gotodeath&quot;
192.168.200.16:12002>

　　

从VIP读取数据



192.168.200.16:12002> get go
&quot;gotodeath&quot;
　　

从Master读取数据



root@dead:/usr/local/etc/keepalived# /usr/local/redis-2.8.13/src/redis-cli -p 12002
127.0.0.1:12002> get go
&quot;gotodeath&quot;
127.0.0.1:12002>
　　

从Slave读取数据



root@gone:/usr/local/etc/keepalived# /usr/local/redis-2.8.13/src/redis-cli -p 12002
127.0.0.1:12002> get go
&quot;gotodeath&quot;
127.0.0.1:12002>



下面，模拟故障产生：

将Master上的Redis进程杀死：

$ sudo killall -9 redis-server

141日志如下：（）









140日志如下：















参考资料：http://heylinux.com/archives/1942.html





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