Redis主从+KeepAlived实现高可用

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，

所以今天总结了下redis主从高可用的搭建，参考了网上一些大神的博客文章，发现很多都是有坑的，所以本人在此分享一次，希望能帮助到大家。

Redis特点

Redis 是完全开源免费的，遵守BSD协议，是一个高性能的key-value数据库。

Redis 与其他 key - value 缓存产品有以下三个特点：

Redis支持数据的持久化，可以将内存中的数据保持在磁盘中，重启的时候可以再次加载进行使用。

Redis不仅仅支持简单的key-value类型的数据，同时还提供如：字符串(String), 哈希(Map), 列表(list), 集合(sets) 和有序集合(sorted sets)等数据结构的存储。

Redis支持数据的备份，即master-slave模式的数据备份。

Redis 优势

性能极高 – Redis能读的速度是100K+次/s,写的速度是80K+次/s 。

丰富的数据类型 – Redis支持二进制案例的 Strings, Lists, Hashes, Sets 及 Ordered Sets 数据类型操作。

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。

丰富的特性 – Redis还支持 publish/subscribe, 通知, key 过期等等特性。

准备环境

Centos7 --> 172.16.81.140 -->主Redis -->主Keepalived

Centos7 --> 172.16.81.141 -->从Redis -->备Keepalived

VIP --> 172.16.81.139

redis（一般3.0版本以上都行）

KeepAlived（直接在线安装的）

Redis编译安装

1、提前准备好的redis软件放在/opt目录下：redis-4.0.6.tar.gz

cd /opt
tar -zxvf redis-4.0.6.tar.gz
mv redis-4.0.6 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

service redis start
#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

引申回到前面的设计模式，我们的思路是以140作为主，141作为从，139作为VIP飘逸地址，应用通过139的6379端口访问redis数据库。

正常运行下，当主节点140宕机后，VIP飘逸到141上，这时141就会接管140成为主节点，140就会成为从节点，继续提供读写操作。

当140恢复正常后，这时140会与141进行一次数据同步，140原有的数据不会丢失，还会同步宕机之间已经写入到141的数据，数据同步完成之后，

VIP会因为权重的原因重新回到140节点上并成为主节点，141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-140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-141配置文件

vim /etc/redis/redis.conf
    bind 0.0.0.0
    port 6379
    daemonize yes
    slaveof 172.16.81.140 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140终端登录测试：

[root@localhost ~]# redis-cli -a 123456
127.0.0.1:6379> INFO
.
.
.
# Replication
role:master
connected_slaves:1
slave0:ip=172.16.81.141,port=6379,state=online,offset=105768,lag=1
master_replid:f83fcc3c98614d770f2205831fef1e877fa3f482
master_replid2:1f25604997a4ad3eb8344e8155990e78acd93312
master_repl_offset:105768
second_repl_offset:447
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:447
repl_backlog_histlen:105322

从节点141终端登录测试：

[root@localhost ~]# redis-cli -a 123456
127.0.0.1:6379> info
.
.
.
# Replication
role:slave
master_host:172.16.81.140
master_port:6379
master_link_status:up
master_last_io_seconds_ago:5
master_sync_in_progress:0
slave_repl_offset:105992
slave_priority:100
slave_read_only:0
connected_slaves:0
master_replid:f83fcc3c98614d770f2205831fef1e877fa3f482
master_replid2:1f25604997a4ad3eb8344e8155990e78acd93312
master_repl_offset:105992
second_repl_offset:447
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:239
repl_backlog_histlen:105754

3、同步测试

主节点140

从节点141

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 {
        172.16.81.139
    }

    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 {
        172.16.81.139
    }

    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 -- 140

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

$REDISCLI SLAVEOF 172.16.81.141 6379 >>$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

$REDISCLI SLAVEOF 172.16.81.141 6379 >>$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 -- 141

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

$REDISCLI SLAVEOF 172.16.81.140 6379 >>$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

$REDISCLI SLAVEOF 172.16.81.140 6379 >>$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！！！

上面是本人亲测过的，如有问题请留言！！！