Redis是我们当下比较流行使用的非关系数据库，可支持多样化的数据类型，多线程高并发支持，redis运行在内存拥有更快的读写。因为redis的表现如此出色，如何能保障redis在运行中能够应对宕机故障，
Redis支持数据的备份，即master-slave模式的数据备份。
性能极高 – Redis能读的速度是100K+次/s,写的速度是80K+次/s
原子 – Redis的所有操作都是原子性的，同时Redis还支持对几个操作全并后的原子性执行。
准备环境
Centos7 --> 10.0.0.7 -->主Redis -->主Keepalived
Centos7 --> 10.0.0.8 -->从Redis -->备Keepalived
VIP --> 10.0.0.122 (此IP必须和主备2台机器同网段但没有被使用)
redis-4.0.0
下载路径：http://download.redis.io/releases/redis-6.0.8.tar.gz
KeepAlived（直接使用yum安装）
Redis编译安装
1、提前准备好的redis软件放在/opt目录下：redis-4.0.0.tar.gz
cd /opt
tar -zxvf redis-4.0.0.tar.gz
mv redis-4.0.0 redis
cd redis
makeMALLOC=libc
make PREFIX=/usr/local/redis install
2、配置redis启动脚本
vim /etc/init.d/redis
#!/bin/sh
#chkconfig:2345 80 90
# Simple Redisinit.d script conceived to work on Linux systems
# as it doesuse of the /proc filesystem.
#配置redis端口号
REDISPORT=6379
#配置redis启动命令路径
EXE=/usr/local/redis/bin/redis-server
#配置redis连接命令路径
CLIEXE=/usr/local/redis/bin/redis-cli
#配置redis运行PID路径
PIDFILE=/var/run/redis_6379.pid
#配置redis的配置文件路径
CONF="/etc/redis/redis.conf"
#配置redis的连接认证密码
REDISPASSWORD=123456
function start () {
if [ -f $PIDFILE ]
then
echo "$PIDFILE exists,process is already running or crashed"
else
echo "Starting Redisserver..."
$EXE $CONF &
fi
}
function stop () {
if [ ! -f $PIDFILE ]
then
echo "$PIDFILE does not exist, process is not running"
else
PID=$(cat $PIDFILE)
echo "Stopping ..."
$CLIEXE -p $REDISPORT -a $REDISPASSWORD shutdown
while [ -x /proc/${PID} ]
do
echo "Waiting forRedis to shutdown ..."
sleep 1
done
echo "Redis stopped"
fi
}
function restart () {
stop
sleep 3
start
}
case "$1" in
start)
start
;;
stop)
stop
;;
restart)
restart
;;
*)
echo -e "\e[31m Please use $0 [start|stop|restart] asfirst argument \e[0m"
;;
esac
授予执行权限：chmod +x /etc/init.d/redis
添加开机启动：
chkconfig --add redis
chkconfig redis on
查看：chkconfig --list | grep redis
此次试验事先关闭了防火墙和selinux，生产环境建议开启防火墙。
3、添加redis命令环境变量
#vi /etc/profile
#添加下一行参数
exportPATH="$PATH:/usr/local/redis/bin"
#环境变量生效
source /etc/profile
4、启动redis服务
systemctl start redis
#检查启动情况
ps -ef | grep redis
注：在我们两台服务器上先执行同样的操作安装完成redis，接下来安装完成后，就直接进入配置主从环境。
Redis主从配置
我们的思路是以10.0.0.7作为主，10.0.0.8作为从，10.0.0.122作为VIP漂移地址，应用通过10.0.0.122的6379端口访问redis数据库。
正常运行下，当主节点10.0.0.7宕机后，VIP飘逸到10.0.0.8上，这时10.0.0.8就会接管10.0.0.7成为主节点，10.0.0.7就会成为从节点，继续提供读写操作。
当10.0.0.7恢复正常后，这时10.0.0.7会与10.0.0.8进行一次数据同步，10.0.0.7原有的数据不会丢失，还会同步宕机之间已经写入到10.0.0.8的数据，数据同步完成之后，
VIP会因为权重的原因重新回到10.0.0.7节点上并成为主节点，10.0.0.8会因为失去VIP会重新成为从节点，恢复到初始状态继续提供不间断的读写服务。
1、配置redis的配置文件
Master-10.0.0.7配置文件
vim /etc/redis/redis.conf
bind 0.0.0.0
port 6379
daemonize yes
requirepass 123456
slave-serve-stale-data yes
slave-read-only no
Slave-10.0.0.8配置文件
vim /etc/redis/redis.conf
bind 0.0.0.0
port 6379
daemonize yes
slaveof 10.0.0.7 6379
masterauth 123456
slave-serve-stale-data yes
slave-read-only no
2、配置完成后重启redis服务！验证主从是否正常。
主节点10.0.0.7终端登录测试：
[root@localhost ~]# redis-cli -a 123456
127.0.0.1:6379> INFO
从节点10.0.0.8终端登录测试：
[root@localhost ~]# redis-cli -a 123456
127.0.0.1:6379> info
3、同步测试
主节点10.0.0.7
从节点10.0.0.8
到此redis的主从已经完成！
KeepAlived配置实现双机热备
使用Keepalived实现VIP，并且通过notify_master、notify_backup、notify_fault、notify_stop来实现容灾。
1、配置Keepalived配置文件
主Keepalived配置文件
vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
acassen@firewall.loc
failover@firewall.loc
sysadmin@firewall.loc
}
notification_email_from Alexandre.Cassen@firewall.loc
smtp_server 192.168.200.1
smtp_connect_timeout 30
router_id redis01
}
vrrp_script chk_redis {
script "/etc/keepalived/script/redis_check.sh"
interval 2
}
vrrp_instance VI_1 {
state MASTER
interface eno16777984
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
chk_redis
}
virtual_ipaddress {
10.0.0.122
}
notify_master /etc/keepalived/script/redis_master.sh
notify_backup /etc/keepalived/script/redis_backup.sh
notify_fault /etc/keepalived/script/redis_fault.sh
notify_stop /etc/keepalived/script/redis_stop.sh
}
备用Keepalived配置文件
vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
acassen@firewall.loc
failover@firewall.loc
sysadmin@firewall.loc
}
notification_email_from Alexandre.Cassen@firewall.loc
smtp_server 192.168.200.1
smtp_connect_timeout 30
router_id redis02
}
vrrp_script chk_redis {
script "/etc/keepalived/script/redis_check.sh"
interval 2
}
vrrp_instance VI_1 {
state BACKUP
interface eno16777984
virtual_router_id 51
priority 99
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
chk_redis
}
virtual_ipaddress {
10.0.0.122
}
notify_master /etc/keepalived/script/redis_master.sh
notify_backup /etc/keepalived/script/redis_backup.sh
notify_fault /etc/keepalived/script/redis_fault.sh
notify_stop /etc/keepalived/script/redis_stop.sh
}
2、配置脚本
Master KeepAlived --10.0.0.7
创建存放脚本目录：mkdir -p /etc/keepalived/script/
cd /etc/keepalived/script/
[root@localhost script]# cat redis_check.sh
#!/bin/bash
ALIVE=`/usr/local/redis/bin/redis-cli -a 123456 PING`
if [ "$ALIVE" == "PONG" ];then
echo $ALIVE
exit 0
else
echo $ALIVE
exit 1
fi
[root@localhost script]# cat redis_master.sh
#!/bin/bash
REDISCLI="/usr/local/redis/bin/redis-cli -a 123456"
LOGFILE="/var/log/keepalived-redis-state.log"
sleep 15
echo "[master]" >> $LOGFILE
date >> $LOGFILE
echo "Being master...." >>$LOGFILE 2>&1
echo "Run SLAVEOF cmd ...">> $LOGFILE
$REDISCLI SLAVEOF 10.0.0.8 6379 >>$LOGFILE 2>&1
if [ $? -ne 0 ];then
echo "data rsync fail." >>$LOGFILE 2>&1
else
echo "data rsync OK." >> $LOGFILE 2>&1
fi
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
if [ $? -ne 0 ];then
echo "Run SLAVEOF NO ONE cmd fail." >>$LOGFILE 2>&1
else
echo "Run SLAVEOF NO ONE cmd OK." >> $LOGFILE 2>&1
fi
[root@localhost script]# cat redis_backup.sh
#!/bin/bash
REDISCLI="/usr/local/redis/bin/redis-cli -a 123456"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "[backup]" >> $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
$REDISCLI SLAVEOF 10.0.0.8 6379 >>$LOGFILE 2>&1
[root@localhost script]# cat redis_fault.sh
#!/bin/bash
LOGFILE=/var/log/keepalived-redis-state.log
echo "[fault]" >> $LOGFILE
date >> $LOGFILE
[root@localhost script]# cat redis_stop.sh
#!/bin/bash
LOGFILE=/var/log/keepalived-redis-state.log
echo "[stop]" >> $LOGFILE
date >> $LOGFILE
Slave KeepAlived -- 10.0.0.8
创建存放脚本目录：mkdir -p /etc/keepalived/script/
cd /etc/keepalived/script/
[root@localhost script]# cat redis_check.sh
#!/bin/bash
ALIVE=`/usr/local/redis/bin/redis-cli -a 123456 PING`
if [ "$ALIVE" == "PONG" ]; then
echo $ALIVE
exit 0
else
echo $ALIVE
exit 1
fi
[root@localhost script]# cat redis_master.sh
#!/bin/bash
REDISCLI="/usr/local/redis/bin/redis-cli -a 123456"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "[master]" >> $LOGFILE
date >> $LOGFILE
echo "Being master...." >>$LOGFILE 2>&1
echo "Run SLAVEOF cmd ...">> $LOGFILE
$REDISCLI SLAVEOF 10.0.0.7 6379 >>$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
[root@localhost script]# cat redis_backup.sh
#!/bin/bash
REDISCLI="/usr/local/redis/bin/redis-cli -a 123456"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "[backup]" >> $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
$REDISCLI SLAVEOF 10.0.0.7 6379 >>$LOGFILE 2>&1
[root@localhost script]# cat redis_fault.sh
#!/bin/bash
LOGFILE=/var/log/keepalived-redis-state.log
echo "[fault]" >> $LOGFILE
date >> $LOGFILE
[root@localhost script]# cat redis_stop.sh
#!/bin/bash
LOGFILE=/var/log/keepalived-redis-state.log
echo "[stop]" >> $LOGFILE
date >> $LOGFILE
3、启动服务
systemctl start keepalived
systemctl enable keepalived
4、测试服务是否正常
ps -ef | grep keepalived
ping 172.16.81.139
查看VIP地址
测试连接redis是否正常
redis-cli -h 172.16.81.139 -p 6379 -a 123456
Keepalived测试完成！！
测试故障转移情况
关闭主redis服务，查看从redis是否会接管VIP变成主？然后再新的主redis141上插入数据，测试当140恢复，数据是否存在？141的是否会变成从节点？
1、主140关闭redis
service redis stop
2、查看141状态
测试VIP连接远程连接
通过INFO可以查看状态信息
可以看到从节点的141已经变成master节点了。
3、插入数据
4、开启140主节点
service redis start
5、查看140和141的主从状态
141的状态，变回了从
140的状态，变回了主
我们在140上查看刚刚在141上插入的新数据
数据存在，证明主从切换是正常的！！！
