redis主从+keepalived 高可用 自动切换
一环境介绍master：172.168.1.69
slave： 172.168.1.57
VIP 172.168.1.253 虚拟IP
二。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。(配置方式，打开redis的配置文件。找到appendonly。默认是appendonly no。改成appendonly yes。)
redis配置文件不可设置只读模式
三。安装前准备工作
1.在主服务器172.168.1.69 上面做下面操作
echo "172.168.1.69test01" >> /etc/hosts
echo "172.168.1.57 test" >> /etc/hosts
2.在从服务器172.168.1.57上面做下面操作
echo "172.168.1.69test01" >> /etc/hosts
echo "172.168.1.57 test" >> /etc/hosts
四：配置redis主从 （略）
端口号 ：P ：6379
密码：123456
启动服务：
# /mnt/tools/redis/bin/redis-server /mnt/tools/redis/etc/redis.conf
主服务器上执行：
#/mnt/tools/redis/bin/redis-cli -h 172.168.1.69 -a 123456 set test 123456
从服务器上执行：
#/mnt/tools/redis/bin/redis-cli -h 172.168.1.57 get test
测试是否已启动
# /mnt/tools/redis/bin/redis-cli ping
性能测试
# /mnt/tools/redis/bin/redis-benchmark
关闭服务
#/mnt/tools/redis/bin/redis-cli -p 6379 shutdown
五：安装配置keepalived （直接yum安装也可以方便简单粗暴不用自己装依赖包）
1.mkdir /root/tools -p
cd /root/tools
wget http://www.keepalived.org/software/keepalived-1.1.17.tar.gz
tar -zxf keepalived*
2.做一个内核连接
# uname -r
3.10.0-123.9.3.el7.x86_64
# ln -s /usr/src/kernels/3.10.0-123.9.3.el7.x86_64 /usr/src/linux
cd keepalived-1.1.17
./configure error（yum install -y openssl openssl-devel yum install popt-devel）
make && make install
移动启动脚本和配置文件
# cp /usr/local/etc/rc.d/init.d/keepalived/etc/init.d/
# cp /usr/local/etc/sysconfig/keepalived/etc/sysconfig/
# mkdir /etc/keepalived 启动脚本中默认指定的配置文件路径
# /bin/cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/
# /bin/cp /usr/local/sbin/keepalived/usr/sbin/
执行上述操作后就可以以 /etc/init.d/keepalived 的方式启动了
/etc/init.d/keepalived start
/etc/init.d/keepalived stop
/etc/init.d/keepalived restart
3.master keepalived.cnf 配置文件
! Configuration File for keepalived
vrrp_script chk_redis {
script "/etc/keepalived/scripts/redis_check.sh"
interval 2
}
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
mcast_src_ip 172.168.1.253
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
chk_redis
}
virtual_ipaddress {
172.168.1.253
}
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：keepalived.cnf 配置文件
! Configuration File for keepalived
vrrp_script chk_redis {
script "/etc/keepalived/scripts/redis_check.sh"
interval 2
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 51
mcast_src_ip 172.168.1.253
priority 10
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
chk_redis
}
virtual_ipaddress {
172.168.1.253
}
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
}
4.在Master和Slave上创建监控Redis的脚本
$mkdir /etc/keepalived/scripts
$vim /etc/keepalived/scripts/redis_check.sh
#!/bin/bash
ALIVE=`/mnt/tools/redis/bin/redis-cli -a 123456 PING`
if [ "$ALIVE" == "PONG" ]; then
echo $ALIVE
exit 0
else
echo $ALIVE
exit 1
fi
5.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
1)首先，在Redis Master上创建notity_master与notify_backup脚本：
$vim /etc/keepalived/scripts/redis_master.sh
#!/bin/bash
REDISCLI="/usr/local/bin/redis-cli -a 123456"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "" >> $LOGFILE
date >> $LOGFILE
echo "Being master...." >> $LOGFILE 2>&1
echo "Run SLAVEOF cmd ..." >> $LOGFILE
$REDISCLI SLAVEOF 172.168.1.57 6379 >> $LOGFILE2>&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
$vim /etc/keepalived/scripts/redis_backup.sh
#!/bin/bash
REDISCLI="/usr/local/bin/redis-cli -a 123456"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "" >> $LOGFILE
date >> $LOGFILE
echo "Being slave...." >> $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 "Run SLAVEOF cmd ..." >> $LOGFILE
$REDISCLI SLAVEOF 172.168.1.57 6379 >> $LOGFILE2>&1
2)在Redis Slave上创建notity_master与notify_backup脚本：
$vim /etc/keepalived/scripts/redis_master.sh
#!/bin/bash
REDISCLI="/usr/local/bin/redis-cli -a 123456"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "" >> $LOGFILE
date >> $LOGFILE
echo "Being master...." >> $LOGFILE 2>&1
echo "Run SLAVEOF cmd ..." >> $LOGFILE
$REDISCLI SLAVEOF 172.168.1.69 6379 >> $LOGFILE2>&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
$vim /etc/keepalived/scripts/redis_backup.sh
#!/bin/bash
REDISCLI="/usr/local/bin/redis-cli -a 123456"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "" >> $LOGFILE
date >> $LOGFILE
echo "Being slave...." >> $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 "Run SLAVEOF cmd ..." >> $LOGFILE
$REDISCLI SLAVEOF 172.168.1.69 6379 >> $LOGFILE2>&1
3)然后在Master与Slave创建如下相同的脚本：
$vim /etc/keepalived/scripts/redis_fault.sh
#!/bin/bash
LOGFILE=/var/log/keepalived-redis-state.log
echo "" >> $LOGFILE
date >> $LOGFILE
$vim /etc/keepalived/scripts/redis_stop.sh
#!/bin/bash
LOGFILE=/var/log/keepalived-redis-state.log
echo "" >> $LOGFILE
date >> $LOGFILE
6.在主从服务器上面给脚本都加上可执行权限：
$chmod +x /etc/keepalived/scripts/*.sh
7.进行相关功能测试
启动Master和slave上的Redis
$/mnt/tools/redis/bin/redis-server /mnt/tools/redis/etc/redis.conf
启动Master和slave上的Keepalived
$
尝试通过VIP连接Redis:
$ redis-cli -h 172.168.1.253 INFO
连接成功，Slave也连接上来了。
role:master
slave0:172.168.1.57,6379,online
尝试插入一些数据：
$ redis-cli -h 172.168.1.69 SET Hello Redis
OK
从VIP读取数据
$ redis-cli -h 172.168.1.253 GET Hello
"Redis"
从Master读取数据
$ redis-cli -h 172.168.1.69 GET Hello
"Redis"
从Slave读取数据
$ redis-cli -h 172.168.1.57 GET Hello
"Redis"
8.通过模拟相关故障，进行功能测试（）
将Master上的Redis进程杀死：
killall -9 redis-server
查看Master上的Keepalived日志
查看Master上的Keepalived日志
$ tail -f /var/log/keepalived-redis-state.log
Thu Sep 27 08:29:01 CST 2012
同时Slave上的日志显示：
$ tail -f /var/log/keepalived-redis-state.log
Being master....
Run SLAVEOF cmd ...
OK Already connected to specified master
Run SLAVEOF NO ONE cmd ...
OK
然后我们可以发现，Slave已经接管服务，并且担任Master的角色了。
$ redis-cli -h 172.168.1.253 INFO
$ redis-cli -h 172.168.1.57 INFO
role:master
然后我们恢复Master的Redis进程(恢复主redis后，需要重启keepalived和从库的redis可恢复正常）
$/etc/init.d/redis start
查看Master上的Keepalived日志
$ tail -f /var/log/keepalived-redis-state.log
Being master....
Run SLAVEOF cmd ...
OK
Run SLAVEOF NO ONE cmd ...
OK
同时Slave上的日志显示：
$ tail -f /var/log/keepalived-redis-state.log
Being slave....
Run SLAVEOF cmd ...
OK
发现目前的Master已经再次恢复了Master的角色，故障切换以及自动恢复都成功了。
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