keepalived实现redis主备切换
试验目标：1：主redis发生故障时，从redis自动切换为主redis。
2：主redis恢复正常后，自动降级为从redis。
试验环境：
主redis：192.168.189.138
从redis：192.168.189.131
VIP：192.168.189.123
主从redis均安装了keepalived与redis，redis已配置好主从。Redis端口44444。
1：制作redis监控与主备切换脚本：
Redis监控脚本：（监控redis是否正常）
# cat /usr/local/scripts/redis_monitor.sh
#!/bin/bash
ALIVE=$(/home/usr/local/redis/bin/redis-cli -h 192.168.189.138 -p 44444 PING)
if [ "$ALIVE" =="PONG" ]; then
echo $ALIVE
exit 0
else
echo $ALIVE
killall -9 keepalived
service network restart
exit 1
fi
redis_master脚本:（用于从redis切换成主redis）
# cat /usr/local/scripts/redis_master.sh
#!/bin/bash
REDISCLI="/home/usr/local/redis/bin/redis-cli -h 192.168.189.138 -p 44444 "
LOGFILE="/home/usr/local/redis/var/keepalived-redis-state.log"
echo "" >>$LOGFILE
date >> $LOGFILE
echo "Being master....">> $LOGFILE 2>&1
echo "Run SLAVEOF cmd ...">> $LOGFILE
#指定自己为131的slave
$REDISCLI SLAVEOF 192.168.189.13144444 >> $LOGFILE2>&1
#延迟10秒，用于数据同步
sleep 10
echo "Run SLAVEOF NO ONE cmd..." >> $LOGFILE
#解除自己的slave状态，成为master
$REDISCLI SLAVEOF NO ONE >>$LOGFILE 2>&1
Redis_backup脚本：（用于主redis切换成从redis）
# cat /usr/local/scripts/redis_backup.sh
#!/bin/bash
REDISCLI="/home/usr/local/redis/bin/redis-cli -h 192.168.189.138 -p 44444"
LOGFILE="/home/usr/local/redis/var/keepalived-redis-state.log"
echo "" >>$LOGFILE
date >> $LOGFILE
echo "Being slave....">> $LOGFILE 2>&1
sleep 15
echo "Run SLAVEOF cmd ...">> $LOGFILE
$REDISCLI SLAVEOF 192.168.189.13144444 >> $LOGFILE2>&1
以上是主redis上的脚本，从redis上的脚本只要更改脚本中相应的IP。
2：配置keepalived
主节点：
# cat /usr/local/keepalived/etc/keepalived/keepalived.conf
global_defs {
router_id LVS_DEVEL
}
vrrp_script redis_monitor { ------监控脚本
script"/usr/local/scripts/redis_monitor.sh"
interval 2
weight 2
}
vrrp_instance VI_1{
state BACKUP --------状态同备用节点一致，为BACKUP
interface eth0
virtual_router_id 51
mcast_src_ip 192.168.189.138
nopreempt ----------设置不抢占IP
priority 100 ----------优先级
advert_int 1
authentication {
auth_type PASS
auth_pass password_123
}
track_script {
redis_monitor -------与上面的监控脚本一致
}
virtual_ipaddress {
192.168.189.123
}
notify_master/usr/local/scripts/redis_master.sh -------keepalived切换为master时运行
notify_backup/usr/local/scripts/redis_backup.sh -------keepalived切换为slave时运行
}
从节点：
# cat /usr/local/keepalived/etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
router_id LVS_DEVEL
}
vrrp_script redis_monitor{
script"/usr/local/scripts/redis_monitor.sh"
interval 2
weight 2
}
vrrp_instance VI_1{
state BACKUP ----------与主节点一致，BAKCUP
interface eth0
virtual_router_id 51
mcast_src_ip 192.168.189.131
priority 99 -----优先级小于主节点
advert_int 1
authentication {
auth_type PASS
auth_pass password_123
}
track_script {
redis_monitor
}
virtual_ipaddress {
192.168.189.123
}
notify_master/usr/local/scripts/redis_master.sh
notify_backup/usr/local/scripts/redis_backup.sh
}
3：开启redis与keepalived
# /usr/local/redis/bin/redis-server /home/usr/local/redis/etc/redis.conf
# /usr/local/keepalived/sbin/keepalived -D -f /usr/local/keepalived/etc/keepalived/keepalived.conf
4：观察测试
启动redis-server后，可以看到138主机抢占了VIP123，并且redis角色为Master
131主机没抢占到123IP，redis角色为Slave
主节点上配置数据，查看从节点是否同步。
主：
从：
以上可看出主备数据同步正常。
1，关闭主redis，查看从节点是否抢占IP，从redis是否变为主redis
#/home/usr/local/redis/bin/redis-cli -h 192.168.189.138 -p 44444 shutdown
查看从节点日志：
以上日志显示131节点抢占到了IP123，成为keepalived主节点。
以上日志显示131节点的redis角色变为Master。
查看131redis角色状态：
131的redis已经成功从slave变为master。
2，恢复138原主节点的redis状态,测试原来的主redis是否会自动降级为slave。
在主节点上重新开启keepalived,和redis（注意要先开启redis，再开启keepalived）。
# /home/usr/local/redis/bin/redis-server /home/usr/local/redis/etc/redis.conf
# /usr/local/keepalived/sbin/keepalived -D -f /usr/local/keepalived/etc/keepalived/keepalived.conf
查看138节点日志：
可以看到keepalived原主节点自动进入BACKUP状态，并未抢占123VIP。
Redis角色也自动变更为Slave。
查看主备redis角色：
试验目标完成！
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