redis 主从配置，自动切换

Posted 2020-10-29

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声明：此文中所用配置方式和脚本逻辑并非原创，脚本和配置都经过本人测试和优化。

基础信息

软件版本：
CentOS7.2.1511 Keepalived v1.3.4 Redis3.2.4
IP信息：
- master: 192.168.56.11
- slave: 192.168.56.12
- vip: 192.168.56.100
Redis配置：
- 安装目录：/usr/local/redis
- 数据目录：/data4/redisdata
- 配置文件：/usr/local/redis/redis.conf
Keepalived配置：
- 安装目录：/usr/local/keepalived
- 配置文件：/etc/keepalived/keepalived.conf
脚本软件包：http://down.51cto.com/data/2444547
- master 脚本压缩包放在master主机，slave脚本压缩包放在slave主机。

初始环境配置(master和slave上都进行操作)

关闭防火墙，SeLinux,配置yum源。

安装必要的软件：

yum -y install gcc gcc+ openssl openssl-devel  tcl wget -y

安装redis


cd /home
wget http://download.redis.io/releases/redis-3.2.4.tar.gz
tar -xf ./redis-3.2.4.tar.gz
mv redis-3.2.4 /usr/local/
cd /usr/local/redis-3.2.4/deps/
make hiredis lua jemalloc linenoise
cd ..
make test
make 
make install
mkdir -p /usr/local/redis/bin
mkdir -p /data4/redisdata
cd /usr/local/redis-3.2.4/src
cp redis-benchmark redis-check-aof redis-cli redis-server mkreleasehdr.sh /usr/local/redis/bin/
cd /usr/local/redis-3.2.4
cp redis.conf /usr/local/redis/
cp /usr/local/bin/redis-cli  /usr/bin/

安装keepalived

cd /home
wget http://www.keepalived.org/software/keepalived-1.3.4.tar.gz
tar xf keepalived-1.3.4.tar.gz 
cd keepalived-1.3.4
./configure 
make
make install

Redis主从配置

在master上修改配置文件/usr/local/redis/redis.conf参数
```
bind 0.0.0.0
daemonize yes
dir /data4/redisdata
```
slave 上修改相同的信息，并添加slaveof的配置：
```
bind 0.0.0.0
daemonize yes
dir /data4/redisdata
slaveof 192.168.56.11 6379
```

master和slave上为redis配置单独用户并启动服务

useradd redisuser
passwd redisuser
chown -R redisuser:redisuser /usr/local/redis/redis.conf
chown -R redisuser:redisuser /usr/local/redis/bin/redis-server
chown redisuser /data4/redisdata
su - redisuser
cd /usr/local/redis
./bin/redis-server ./redis.conf

Redis口令信息：

username: redisuser
password: redi13%&

Keepalived 主备配置

在master节点修改/etc/keepalived/keepalived.conf为如下配置：

global_defs {
   lvs_id LVS_redis
}
vrrp_script chk_redis { 
    script "/etc/keepalived/scripts/redis_check.sh"
    weight -20
    interval 2                                     
} 

vrrp_instance VI_1 { 
    state backup                            
    interface eth0                          
    virtual_router_id 51
    nopreempt
    priority 200      
    advert_int 5                      
    track_script { 
        chk_redis                     
    } 
    virtual_ipaddress { 
         192.168.56.100
    }
    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 
}

Keepalived 的Backup节点修改/etc/keepalived/keepalived.conf配置文件内容为如下配置：


global_defs {
  lvs_id LVS_redis
}

vrrp_script chk_redis { 
    script "/etc/keepalived/scripts/redis_check.sh"   
    weight  -20 
    interval 2                                       
} 
vrrp_instance VI_1 { 
    state backup                                
    interface eth0                              
    virtual_router_id 51 
    priority 190    
    advert_int  5                            
    track_script { 
         chk_redis                   
    } 
    virtual_ipaddress { 
         192.168.56.100                    
    } 
    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 
}

添加主备keepalived状态脚本文件
- 上传脚本压缩包到/etc/keepalived/目录下，解压到scripts目录，并添加脚本执行权限。
- 创建日志记录目录：
```
mkdir /var/log/keepalived/
```
启动keepalived

先启动主节点keepalved,再启动slave节点
```
systemctl start keepalived
```
查看keepalived和redis工作状态
- 主节点上查看有vip,从节点上无vip
```
ip a|grep gl
```
- 主redis为master状态，从节点为slave状态
```
redis-cli  info replication
```
测试redis+keepalived主从是否正常
- 分别依次关闭master上的redis和keepalived，查看主从状态和vip飘移情况。
- 查看master和slave上的各项日志情况：
```
tail -f /var/log/keepalived/redis-state.log 
tail -f /var/log/messages
```
故障处理

当redis-master出现问题停机或者应用终止后，需要对进行故障排查，正确的恢复启动顺序如下：
1. 使用redisuser 启动masrer,并与当前的slave(此时已经切换为master)进行数据同步：
```
 su - redisuser 
 cd /usr/local/redis
 ./bin/redis-server ./redis.conf  #启动redis
 netstat -lntp
 sh /etc/keepalived/scripts/redis_backup.sh # 使用脚本同步redis
 redis-cli  info replication  #查看同步状态
```
1. 同步完成之后切换为root,启动keepalived，此时由于是不抢占模式，VIP仍然在slave上。
```
[[email protected] ~]# systemctl start keepalived
[[email protected] ~]# redis-cli  INFO replication
```
1. 重启备用节点的keepalived,脚本自动完成主备切换
```
[[email protected] ~]# systemctl restart keepalived
[[email protected] ~]# redis-cli  INFO replication
```

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基础信息

初始环境配置(master和slave上都进行操作)

Redis主从配置

Keepalived 主备配置

故障处理